refactor(custody): drop the single-implementation CustodyStore trait

fix(vault): apply Shamir custody review feedback
feat(vault)!: add multi-operator Shamir custody
2026-09-11 15:45:21 +02:00 · 2026-09-11 15:02:59 +02:00 · 2026-09-11 10:48:01 +02:00
37 changed files with 1993 additions and 263 deletions
--- a/mise.lock
+++ b/mise.lock
@@ -152,5 +152,8 @@ url = "https://github.com/astral-sh/python-build-standalone/releases/download/20
 provenance = "github-attestations"

 [[tools.rust]]
-version = "1.95.0"
+version = "1.98.1"
 backend = "core:rust"
+
+[tools.rust.options]
+components = "clippy,rust-analyzer"
--- a/mise.toml
+++ b/mise.toml
@@ -4,7 +4,7 @@
 "cargo:cargo-vet" = "0.10.2"
 flutter = "3.41.7-stable"
 protoc = "29.6"
-rust = { version = "1.95.0", components = "clippy,rust-analyzer" }
+rust = { version = "latest", components = "clippy,rust-analyzer" }
 "cargo:cargo-features-manager" = "0.12.0"
 "cargo:cargo-nextest" = "0.9.133"
 "cargo:cargo-shear" = "latest"
--- a/server/Cargo.lock
+++ b/server/Cargo.lock
@@ -24,7 +24,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d122413f284cf2d62fb1b7db97e02edb8cda96d769b16e443a4f6195e35662b0"
 dependencies = [
 "crypto-common 0.1.7",
- "generic-array",
+ "generic-array 0.14.7",
 ]

 [[package]]
@@ -504,7 +504,7 @@ dependencies = [
 "async-trait",
 "auto_impl",
 "either",
- "elliptic-curve",
+ "elliptic-curve 0.13.8",
 "k256",
 "thiserror",
 ]
@@ -787,6 +787,7 @@ dependencies = [
 "tonic",
 "tracing",
 "tracing-subscriber",
+ "vsss-rs",
 "x25519-dalek 2.0.1",
 ]

@@ -821,7 +822,7 @@ dependencies = [
 "ark-serialize 0.3.0",
 "ark-std 0.3.0",
 "derivative",
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-traits",
 "paste",
 "rustc_version 0.3.3",
@@ -841,7 +842,7 @@ dependencies = [
 "derivative",
 "digest 0.10.7",
 "itertools 0.10.5",
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-traits",
 "paste",
 "rustc_version 0.4.1",
@@ -862,7 +863,7 @@ dependencies = [
 "digest 0.10.7",
 "educe",
 "itertools 0.13.0",
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-traits",
 "paste",
 "zeroize",
@@ -904,7 +905,7 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "db2fd794a08ccb318058009eefdf15bcaaaaf6f8161eb3345f907222bac38b20"
 dependencies = [
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-traits",
 "quote",
 "syn 1.0.109",
@@ -916,7 +917,7 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7abe79b0e4288889c4574159ab790824d0033b9fdcb2a112a3182fac2e514565"
 dependencies = [
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-traits",
 "proc-macro2",
 "quote",
@@ -929,7 +930,7 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09be120733ee33f7693ceaa202ca41accd5653b779563608f1234f78ae07c4b3"
 dependencies = [
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-traits",
 "proc-macro2",
 "quote",
@@ -954,7 +955,7 @@ checksum = "adb7b85a02b83d2f22f89bd5cac66c9c89474240cb6207cb1efc16d098e822a5"
 dependencies = [
 "ark-std 0.4.0",
 "digest 0.10.7",
- "num-bigint",
+ "num-bigint 0.4.6",
 ]

 [[package]]
@@ -966,7 +967,7 @@ dependencies = [
 "ark-std 0.5.0",
 "arrayvec",
 "digest 0.10.7",
- "num-bigint",
+ "num-bigint 0.4.6",
 ]

 [[package]]
@@ -1196,6 +1197,12 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4c7f02d4ea65f2c1853089ffd8d2787bdbc63de2f0d29dedbcf8ccdfa0ccd4cf"

+[[package]]
+name = "base16ct"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd307490d624467aa6f74b0eabb77633d1f758a7b25f12bceb0b22e08d9726f6"
+
 [[package]]
 name = "base64"
 version = "0.22.1"
@@ -1284,7 +1291,7 @@ version = "0.10.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
 dependencies = [
- "generic-array",
+ "generic-array 0.14.7",
 ]

 [[package]]
@@ -1553,6 +1560,12 @@ version = "0.8.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"

+[[package]]
+name = "cpubits"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "15b85f9c39137c3a891689859392b1bd49812121d0d61c9caf00d46ed5ce06ae"
+
 [[package]]
 name = "cpufeatures"
 version = "0.2.17"
@@ -1613,19 +1626,35 @@ version = "0.5.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0dc92fb57ca44df6db8059111ab3af99a63d5d0f8375d9972e319a379c6bab76"
 dependencies = [
- "generic-array",
+ "generic-array 0.14.7",
 "rand_core 0.6.4",
 "subtle",
 "zeroize",
 ]

+[[package]]
+name = "crypto-bigint"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a52aa3fcda4e6302a9f48734f234d35d4721b96f8fe07d073f07ce9df4f0271"
+dependencies = [
+ "cpubits",
+ "ctutils",
+ "hybrid-array",
+ "num-traits",
+ "rand_core 0.10.1",
+ "serdect 0.4.3",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "crypto-common"
 version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
 dependencies = [
- "generic-array",
+ "generic-array 0.14.7",
 "rand_core 0.6.4",
 "typenum",
 ]
@@ -1647,6 +1676,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7d5515a3834141de9eafb9717ad39eea8247b5674e6066c404e8c4b365d2a29e"
 dependencies = [
 "cmov",
+ "subtle",
 ]

 [[package]]
@@ -1809,7 +1839,7 @@ dependencies = [
 "asn1-rs",
 "displaydoc",
 "nom",
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-traits",
 "rusticata-macros",
 ]
@@ -1928,7 +1958,7 @@ version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d3dd60d1080a57a05ab032377049e0591415d2b31afd7028356dbf3cc6dcb066"
 dependencies = [
- "generic-array",
+ "generic-array 0.14.7",
 ]

 [[package]]
@@ -2006,9 +2036,9 @@ checksum = "ee27f32b5c5292967d2d4a9d7f1e0b0aed2c15daded5a60300e4abb9d8020bca"
 dependencies = [
 "der 0.7.10",
 "digest 0.10.7",
- "elliptic-curve",
+ "elliptic-curve 0.13.8",
 "rfc6979",
- "serdect",
+ "serdect 0.2.0",
 "signature 2.2.0",
 "spki 0.7.3",
 ]
@@ -2040,20 +2070,52 @@ version = "0.13.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b5e6043086bf7973472e0c7dff2142ea0b680d30e18d9cc40f267efbf222bd47"
 dependencies = [
- "base16ct",
- "crypto-bigint",
+ "base16ct 0.2.0",
+ "crypto-bigint 0.5.5",
 "digest 0.10.7",
- "ff",
- "generic-array",
- "group",
+ "ff 0.13.1",
+ "generic-array 0.14.7",
+ "group 0.13.0",
 "pkcs8 0.10.2",
 "rand_core 0.6.4",
- "sec1",
- "serdect",
+ "sec1 0.7.3",
+ "serdect 0.2.0",
 "subtle",
 "zeroize",
 ]

+[[package]]
+name = "elliptic-curve"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d65aa39b3a5c1c9c1b745c9a019234bb7a21b77abcb4f4d266d706e2d577d65"
+dependencies = [
+ "base16ct 1.0.0",
+ "crypto-bigint 0.7.5",
+ "crypto-common 0.2.1",
+ "ff 0.14.0",
+ "group 0.14.0",
+ "hybrid-array",
+ "pkcs8 0.11.0",
+ "rand_core 0.10.1",
+ "sec1 0.8.1",
+ "serdect 0.4.3",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "elliptic-curve-tools"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a0d5e534f103b079a71ef1d66c6e62c89413f1b62709ca11f744429b4afe5b4"
+dependencies = [
+ "elliptic-curve 0.14.1",
+ "heapless",
+ "serde",
+ "serdect 0.4.3",
+]
+
 [[package]]
 name = "enum-ordinalize"
 version = "4.3.2"
@@ -2128,6 +2190,16 @@ dependencies = [
 "subtle",
 ]

+[[package]]
+name = "ff"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1f686ab92a9fb0eaf188f6c6c87b89490baa6fdb0db4544ba4dc47f7942489f"
+dependencies = [
+ "rand_core 0.10.1",
+ "subtle",
+]
+
 [[package]]
 name = "fiat-crypto"
 version = "0.2.9"
@@ -2324,6 +2396,17 @@ dependencies = [
 "zeroize",
 ]

+[[package]]
+name = "generic-array"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb130435a959a8d525e6bca66ff6c40981a300ee96d70e3ef56f046556d614a3"
+dependencies = [
+ "rustversion",
+ "serde_core",
+ "typenum",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.17"
@@ -2383,11 +2466,22 @@ version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f0f9ef7462f7c099f518d754361858f86d8a07af53ba9af0fe635bbccb151a63"
 dependencies = [
- "ff",
+ "ff 0.13.1",
 "rand_core 0.6.4",
 "subtle",
 ]

+[[package]]
+name = "group"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fd1a1c7a5206c5b7a3f5a0d7ccd3ff85d0c8f5133d62a02680255b0004af5f4"
+dependencies = [
+ "ff 0.14.0",
+ "rand_core 0.10.1",
+ "subtle",
+]
+
 [[package]]
 name = "h2"
 version = "0.4.13"
@@ -2407,6 +2501,15 @@ dependencies = [
 "tracing",
 ]

+[[package]]
+name = "hash32"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47d60b12902ba28e2730cd37e95b8c9223af2808df9e902d4df49588d1470606"
+dependencies = [
+ "byteorder",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.12.3"
@@ -2447,6 +2550,16 @@ version = "0.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4f467dd6dccf739c208452f8014c75c18bb8301b050ad1cfb27153803edb0f51"

+[[package]]
+name = "heapless"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "25ba4bd83f9415b58b4ed8dc5714c76e626a105be4646c02630ad730ad3b5aa4"
+dependencies = [
+ "hash32",
+ "stable_deref_trait",
+]
+
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -2539,11 +2652,13 @@ checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"

 [[package]]
 name = "hybrid-array"
-version = "0.4.11"
+version = "0.4.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08d46837a0ed51fe95bd3b05de33cd64a1ee88fc797477ca48446872504507c5"
+checksum = "27f864f10dfb56725ce5ce5472bc52252c8f93a4ab86327122cebf62c5f59a17"
 dependencies = [
 "ctutils",
+ "serde",
+ "subtle",
 "typenum",
 "zeroize",
 ]
@@ -2809,7 +2924,7 @@ version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "879f10e63c20629ecabbb64a8010319738c66a5cd0c29b02d63d272b03751d01"
 dependencies = [
- "generic-array",
+ "generic-array 0.14.7",
 ]

 [[package]]
@@ -2946,17 +3061,17 @@ checksum = "f6e3919bbaa2945715f0bb6d3934a173d1e9a59ac23767fbaaef277265a7411b"
 dependencies = [
 "cfg-if",
 "ecdsa",
- "elliptic-curve",
+ "elliptic-curve 0.13.8",
 "once_cell",
- "serdect",
+ "serdect 0.2.0",
 "sha2 0.10.9",
 "signature 2.2.0",
 ]

 [[package]]
 name = "kameo"
-version = "0.20.0"
-source = "git+https://github.com/hdbg/kameo.git?rev=805b417#805b41783fe90b54827ecad142b422c7a9b69b9a"
+version = "0.22.2"
+source = "git+https://github.com/hdbg/kameo.git?rev=3bbebac#3bbebac9f2a943be75588d80826e6bea45079d5f"
 dependencies = [
 "downcast-rs",
 "dyn-clone",
@@ -2969,8 +3084,8 @@ dependencies = [

 [[package]]
 name = "kameo_actors"
-version = "0.5.0"
-source = "git+https://github.com/hdbg/kameo.git?rev=805b417#805b41783fe90b54827ecad142b422c7a9b69b9a"
+version = "0.8.1"
+source = "git+https://github.com/hdbg/kameo.git?rev=3bbebac#3bbebac9f2a943be75588d80826e6bea45079d5f"
 dependencies = [
 "futures",
 "glob",
@@ -2981,14 +3096,13 @@ dependencies = [

 [[package]]
 name = "kameo_macros"
-version = "0.20.0"
-source = "git+https://github.com/hdbg/kameo.git?rev=805b417#805b41783fe90b54827ecad142b422c7a9b69b9a"
+version = "0.21.1"
+source = "git+https://github.com/hdbg/kameo.git?rev=3bbebac#3bbebac9f2a943be75588d80826e6bea45079d5f"
 dependencies = [
- "darling 0.23.0",
 "heck",
 "proc-macro2",
 "quote",
- "syn 2.0.117",
+ "syn 3.0.5",
 ]

 [[package]]
@@ -3332,6 +3446,17 @@ dependencies = [
 "num-traits",
 ]

+[[package]]
+name = "num-bigint"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93e7820bc0a80a0238e650327316f929ba18d5be054b647490a3a6a339f3e7c0"
+dependencies = [
+ "num-integer",
+ "num-traits",
+ "serde",
+]
+
 [[package]]
 name = "num-conv"
 version = "0.2.1"
@@ -4226,7 +4351,7 @@ dependencies = [
 "bytes",
 "fastrlp 0.3.1",
 "fastrlp 0.4.0",
- "num-bigint",
+ "num-bigint 0.4.6",
 "num-integer",
 "num-traits",
 "parity-scale-codec",
@@ -4453,11 +4578,26 @@ version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d3e97a565f76233a6003f9f5c54be1d9c5bdfa3eccfb189469f11ec4901c47dc"
 dependencies = [
- "base16ct",
+ "base16ct 0.2.0",
 "der 0.7.10",
- "generic-array",
+ "generic-array 0.14.7",
 "pkcs8 0.10.2",
- "serdect",
+ "serdect 0.2.0",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "sec1"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d56d437c2f19203ce5f7122e507831de96f3d2d4d3be5af44a0b0a09d8a80e4d"
+dependencies = [
+ "base16ct 1.0.0",
+ "ctutils",
+ "der 0.8.0",
+ "hybrid-array",
+ "serdect 0.4.3",
 "subtle",
 "zeroize",
 ]
@@ -4619,7 +4759,17 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a84f14a19e9a014bb9f4512488d9829a68e04ecabffb0f9904cd1ace94598177"
 dependencies = [
- "base16ct",
+ "base16ct 0.2.0",
+ "serde",
+]
+
+[[package]]
+name = "serdect"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "66cf8fedced2fcf12406bcb34223dffb92eaf34908ede12fed414c82b7f00b3e"
+dependencies = [
+ "base16ct 1.0.0",
 "serde",
 ]

@@ -4665,6 +4815,17 @@ dependencies = [
 "keccak 0.2.0",
 ]

+[[package]]
+name = "sha3"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bc9bad02c26382724b2d2692c6f179285e4b54eeecd7968f52a50059c3c11759"
+dependencies = [
+ "digest 0.11.2",
+ "keccak 0.2.0",
+ "sponge-cursor",
+]
+
 [[package]]
 name = "sha3-asm"
 version = "0.1.6"
@@ -4675,6 +4836,17 @@ dependencies = [
 "cfg-if",
 ]

+[[package]]
+name = "shake"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09057cb2149ad4cbd2da1e26b351f9a4c354219421229c69c3063e6f61947c4a"
+dependencies = [
+ "digest 0.11.2",
+ "keccak 0.2.0",
+ "sponge-cursor",
+]
+
 [[package]]
 name = "sharded-slab"
 version = "0.1.7"
@@ -4808,6 +4980,12 @@ dependencies = [
 "der 0.8.0",
 ]

+[[package]]
+name = "sponge-cursor"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3a0219bd7d979d58245a4f41f695e1ac9f8befdffadd7f61f1bae9e39abc6620"
+
 [[package]]
 name = "sqlite-wasm-rs"
 version = "0.5.3"
@@ -4935,6 +5113,17 @@ dependencies = [
 "unicode-ident",
 ]

+[[package]]
+name = "syn"
+version = "3.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "12df2e0110f65b775f769bb17ef989067a1d931b2eb822bd4346631eeada89f9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
 [[package]]
 name = "syn-solidity"
 version = "1.5.7"
@@ -5575,6 +5764,29 @@ version = "0.9.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"

+[[package]]
+name = "vsss-rs"
+version = "6.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6bfc736cfd88115aedb95ba84bc2d428fe351e92a56f69fce090af301402d91"
+dependencies = [
+ "crypto-bigint 0.7.5",
+ "elliptic-curve 0.14.1",
+ "elliptic-curve-tools",
+ "ff 0.14.0",
+ "generic-array 1.4.2",
+ "hex",
+ "hybrid-array",
+ "num-bigint 0.5.1",
+ "num-traits",
+ "rand_core 0.10.1",
+ "serde",
+ "sha3 0.12.0",
+ "shake",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "wait-timeout"
 version = "0.2.1"
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -12,8 +12,8 @@ base64 = "0.22.1"
 chrono = { version = "0.4.44", features = ["serde"] }
 futures = "0.3.32"
 k256 = { version = "0.13.4", features = ["ecdsa", "pkcs8"] }
-kameo = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
-kameo_actors = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
+kameo = {git = "https://github.com/hdbg/kameo.git", rev = "3bbebac"}
+kameo_actors = {git = "https://github.com/hdbg/kameo.git", rev = "3bbebac"}
 hmac = "0.13.0"
 miette = { version = "7.6.0", features = ["fancy", "serde"] }
 ml-dsa = { version = "0.1.0-rc.9", features = ["zeroize"] }
@@ -78,6 +78,7 @@ pub_underscore_fields = "allow"
 redundant_pub_crate = "allow" 
 uninhabited_references = "allow" # safe with unsafe_code = "forbid" and standard uninhabited pattern (match *self {})
 too-many-lines = "allow" # this is a very common pattern in server code, and it's not always possible to break it down into smaller modules without hurting readability
+unused_async_trait_impl = "allow" # too pedantic

 # restriction lints
 alloc_instead_of_core = "warn"
--- a/server/crates/arbiter-client/src/client.rs
+++ b/server/crates/arbiter-client/src/client.rs
@@ -94,7 +94,6 @@ impl ArbiterClient {
    }

    #[cfg(feature = "evm")]
-    #[expect(clippy::unused_async, reason = "false positive")]
    pub async fn evm_wallets(&self) -> Result<Vec<ArbiterEvmWallet>, ArbiterClientError> {
        todo!("fetch EVM wallet list from server")
    }
--- a/server/crates/arbiter-proto/src/lib.rs
+++ b/server/crates/arbiter-proto/src/lib.rs
@@ -23,6 +23,10 @@ pub mod proto {
            tonic::include_proto!("arbiter.operator.evm");
        }

+        pub mod governance {
+            tonic::include_proto!("arbiter.operator.governance");
+        }
+
        pub mod sdk_client {
            tonic::include_proto!("arbiter.operator.sdk_client");
        }
@@ -34,6 +38,10 @@ pub mod proto {
                tonic::include_proto!("arbiter.operator.vault.bootstrap");
            }

+            pub mod rekey {
+                tonic::include_proto!("arbiter.operator.vault.rekey");
+            }
+
            pub mod unseal {
                tonic::include_proto!("arbiter.operator.vault.unseal");
            }
--- a/server/crates/arbiter-server/Cargo.toml
+++ b/server/crates/arbiter-server/Cargo.toml
@@ -51,6 +51,7 @@ subtle = "2.6.1"
 x25519-dalek.workspace = true
 k256.workspace = true
 kameo_actors.workspace = true
+vsss-rs = "6.0.1"

 [dev-dependencies]
 proptest = "1.11.0"
--- a/server/crates/arbiter-server/migrations/2026-02-14-171124-0000_init/up.sql
+++ b/server/crates/arbiter-server/migrations/2026-02-14-171124-0000_init/up.sql
@@ -37,7 +37,8 @@ create table if not exists tls_history (
 create table if not exists arbiter_settings (
    id INTEGER not null PRIMARY KEY CHECK (id = 1), -- singleton row, id must be 1
    root_key_id integer references root_key_history (id) on delete RESTRICT, -- if null, means wasn't bootstrapped yet
-    tls_id integer references tls_history (id) on delete RESTRICT
+    tls_id integer references tls_history (id) on delete RESTRICT,
+    shamir_threshold integer
 ) STRICT;

 insert into arbiter_settings (id) values (1) on conflict do nothing;
@@ -56,6 +57,7 @@ create table if not exists operator (

    share blob not null,
    share_nonce blob not null,
+    share_salt blob not null,

    created_at integer not null default(unixepoch ('now')),
    updated_at integer not null default(unixepoch ('now'))
--- a/server/crates/arbiter-server/src/actors/bootstrap.rs
+++ b/server/crates/arbiter-server/src/actors/bootstrap.rs
@@ -1,119 +1,160 @@
-use crate::db::{self, DatabasePool, schema};
+use crate::{
+    actors::vault::events,
+    db::{self, schema},
+};
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_proto::{BOOTSTRAP_PATH, home_path};

 use diesel::QueryDsl;
 use diesel_async::RunQueryDsl;
-use kameo::{Actor, messages};
+use kameo::{
+    Actor,
+    actor::ActorRef,
+    messages,
+    prelude::{Context, Message},
+};
+use kameo_actors::message_bus::{MessageBus, Register};
 use rand::{RngExt, distr::Alphanumeric, rngs::SysRng};
 use rand_core::UnwrapErr;
 use std::path::{Path, PathBuf};
 use subtle::ConstantTimeEq as _;
-use thiserror::Error;
 use tracing::warn;

 const TOKEN_LENGTH: usize = 64;

 async fn write_token_file(path: &Path, content: &str) -> Result<(), std::io::Error> {
+    if let Some(parent) = path.parent() {
+        tokio::fs::create_dir_all(parent).await?;
+    }
    tokio::fs::write(path, content.as_bytes()).await?;
-
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt as _;
        tokio::fs::set_permissions(path, std::fs::Permissions::from_mode(0o600)).await?;
    }
-
    Ok(())
 }

+async fn remove_token_file(path: &Path) {
+    match tokio::fs::remove_file(path).await {
+        Ok(()) => {}
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {}
+        Err(error) => warn!(?error, ?path, "Failed to remove bootstrap token file"),
+    }
+}
+
 async fn generate_token(path: &Path) -> Result<SafeCell<[u8; TOKEN_LENGTH]>, std::io::Error> {
    let mut cell = SafeCell::new([0u8; TOKEN_LENGTH]);
    {
        let mut buf = cell.write();
-        for (slot, b) in buf
+        for (slot, byte) in buf
            .iter_mut()
            .zip(UnwrapErr(SysRng).sample_iter(Alphanumeric))
        {
-            *slot = b;
+            *slot = byte;
        }
    }
-
-    let token_str = cell.read_inline(|buf| String::from_utf8_lossy(buf.as_ref()).into_owned());
-
-    write_token_file(path, &token_str).await?;
-
+    let token = cell.read_inline(|buf| String::from_utf8_lossy(buf.as_ref()).into_owned());
+    write_token_file(path, &token).await?;
    Ok(cell)
 }

-#[derive(Error, Debug)]
+#[derive(Debug, thiserror::Error)]
 pub enum Error {
    #[error("Database error: {0}")]
    Database(#[from] db::PoolError),
-
    #[error("I/O error: {0}")]
    Io(#[from] std::io::Error),
-
    #[error("Database query error: {0}")]
    Query(#[from] diesel::result::Error),
 }

-#[derive(Actor)]
+/// Custodian of the one-time bootstrap token.
+///
+/// The token authorises registering operator identities before the vault
+/// exists. A Shamir committee needs every member registered before it can be
+/// declared, so the token stays valid across several registrations and is
+/// retired by the `Bootstrapped` event rather than by first use, whichever
+/// bootstrap path fired it.
+///
+/// Every daemon start mints a fresh token and overwrites the file: a token
+/// handed out by an earlier run is dead.
 pub struct Bootstrapper {
    token: Option<SafeCell<[u8; TOKEN_LENGTH]>>,
    token_path: Option<PathBuf>,
+    events: ActorRef<MessageBus>,
 }

-impl Bootstrapper {
-    pub async fn new(db: &DatabasePool) -> Result<Self, Error> {
-        let row_count: i64 = {
-            let mut conn = db.get().await?;
+impl Actor for Bootstrapper {
+    type Args = Self;
+    type Error = std::convert::Infallible;

-            schema::operator::table
-                .count()
-                .get_result(&mut conn)
-                .await?
-        };
-
-        let (token, token_path) = if row_count == 0 {
-            let path = home_path()?.join(BOOTSTRAP_PATH);
-            let token = generate_token(&path).await?;
-            (Some(token), Some(path))
-        } else {
-            (None, None)
-        };
-
-        Ok(Self { token, token_path })
+    async fn on_start(args: Self::Args, actor_ref: ActorRef<Self>) -> Result<Self, Self::Error> {
+        let _ = args
+            .events
+            .tell(Register(actor_ref.recipient::<events::Bootstrapped>()))
+            .await;
+        Ok(args)
    }
 }

 impl Bootstrapper {
-    fn is_correct_token(&mut self, token: &[u8]) -> bool {
-        self.token.as_mut().is_some_and(|expected| {
-            expected.read_inline(|exp| bool::from(exp.as_ref().ct_eq(token)))
+    pub async fn new(db: &db::DatabasePool, events: ActorRef<MessageBus>) -> Result<Self, Error> {
+        let path = home_path()?.join(BOOTSTRAP_PATH);
+        let mut conn = db.get().await?;
+
+        let bootstrapped = schema::arbiter_settings::table
+            .select(schema::arbiter_settings::root_key_id)
+            .first::<Option<i32>>(&mut conn)
+            .await?
+            .is_some();
+        if bootstrapped {
+            // A token file can outlive the bootstrap that made it obsolete:
+            // the daemon may have been killed before the event was handled.
+            remove_token_file(&path).await;
+            return Ok(Self {
+                token: None,
+                token_path: None,
+                events,
+            });
+        }
+
+        Ok(Self {
+            token: Some(generate_token(&path).await?),
+            token_path: Some(path),
+            events,
        })
    }
-}

-#[messages]
-impl Bootstrapper {
-    #[message]
-    pub async fn consume_token(&mut self, token: Vec<u8>) -> bool {
-        if self.is_correct_token(&token) {
-            self.token = None;
-            if let Some(path) = self.token_path.take()
-                && let Err(e) = tokio::fs::remove_file(&path).await
-            {
-                warn!(error = ?e, path = ?path, "Failed to delete bootstrap token file after consumption");
-            }
-            true
-        } else {
-            false
+    async fn forget(&mut self) {
+        self.token = None;
+        if let Some(path) = self.token_path.take() {
+            remove_token_file(&path).await;
        }
    }
 }

+impl Message<events::Bootstrapped> for Bootstrapper {
+    type Reply = ();
+
+    async fn handle(
+        &mut self,
+        _: events::Bootstrapped,
+        _ctx: &mut Context<Self, Self::Reply>,
+    ) -> Self::Reply {
+        self.forget().await;
+    }
+}
+    
 #[messages]
 impl Bootstrapper {
+    #[message]
+    pub fn verify_token(&mut self, token: Vec<u8>) -> bool {
+        self.token.as_mut().is_some_and(|expected| {
+            expected.read_inline(|bytes| bool::from(bytes.as_ref().ct_eq(token.as_slice())))
+        })
+    }
+
    #[message]
    pub fn get_token(&mut self) -> Option<String> {
        self.token
--- a/server/crates/arbiter-server/src/actors/mod.rs
+++ b/server/crates/arbiter-server/src/actors/mod.rs
@@ -1,7 +1,7 @@
 use crate::{
    actors::{
        bootstrap::Bootstrapper, evm::EvmActor, flow_coordinator::FlowCoordinator,
-        operator_registry::OperatorRegistry, vault::Vault,
+        operator_registry::OperatorRegistry, vault::Vault, vault_coordinator::VaultCoordinator,
    },
    db,
 };
@@ -15,20 +15,22 @@ pub mod evm;
 pub mod flow_coordinator;
 pub mod operator_registry;
 pub mod vault;
+pub mod vault_coordinator;

 #[derive(Error, Debug)]
 pub enum SpawnError {
    #[error("Failed to spawn Bootstrapper actor")]
    Bootstrapper(#[from] bootstrap::Error),
-
    #[error("Failed to spawn Vault actor")]
    Vault(#[from] vault::Error),
+    #[error("Failed to spawn VaultCoordinator actor")]
+    VaultCoordinator(#[from] vault_coordinator::Error),
 }

-/// Long-lived actors that are shared across all connections and handle global state and operations
 #[derive(Clone)]
 pub struct GlobalActors {
    pub vault: ActorRef<Vault>,
+    pub vault_coordinator: ActorRef<VaultCoordinator>,
    pub bootstrapper: ActorRef<Bootstrapper>,
    pub flow_coordinator: ActorRef<FlowCoordinator>,
    pub operator_registry: ActorRef<OperatorRegistry>,
@@ -42,18 +44,22 @@ impl GlobalActors {
    }

    pub async fn spawn(db: db::DatabasePool) -> Result<Self, SpawnError> {
-        let message_bus = Self::spawn_message_bus();
-        let key_holder = Vault::spawn(Vault::new(db.clone(), message_bus.clone()).await?);
+        let events = Self::spawn_message_bus();
+        let vault = Vault::spawn(Vault::new(db.clone(), events.clone()).await?);
+        let bootstrapper = Bootstrapper::spawn(Bootstrapper::new(&db, events.clone()).await?);
+        let vault_coordinator =
+            VaultCoordinator::spawn(VaultCoordinator::new(db.clone(), vault.clone()));
        let operator_registry = OperatorRegistry::spawn(OperatorRegistry::default());
        Ok(Self {
-            bootstrapper: Bootstrapper::spawn(Bootstrapper::new(&db).await?),
-            evm: EvmActor::spawn(EvmActor::new(key_holder.clone(), db)),
-            vault: key_holder,
+            bootstrapper,
+            evm: EvmActor::spawn(EvmActor::new(vault.clone(), db.clone())),
+            vault,
+            vault_coordinator,
            flow_coordinator: FlowCoordinator::spawn(FlowCoordinator::new(
                operator_registry.clone(),
            )),
            operator_registry,
-            events: message_bus,
+            events,
        })
    }
 }
--- a/server/crates/arbiter-server/src/actors/operator_registry.rs
+++ b/server/crates/arbiter-server/src/actors/operator_registry.rs
@@ -20,8 +20,8 @@ impl Actor for OperatorRegistry {

    type Error = Infallible;

-    async fn on_start(args: Self::Args, _: ActorRef<Self>) -> Result<Self, Self::Error> {
-        Ok(args)
+    fn on_start(args: Self::Args, _: ActorRef<Self>) -> impl Future<Output = Result<Self, Self::Error>> {
+        std::future::ready(Ok(args))
    }

    async fn on_link_died(
--- a/server/crates/arbiter-server/src/actors/vault/mod.rs
+++ b/server/crates/arbiter-server/src/actors/vault/mod.rs
@@ -1,15 +1,17 @@
 use crate::{
    crypto::{
-        KeyCell, derive_key,
+        KeyCell,
        encryption::v1::{self, Nonce},
        integrity::v1::HmacSha256,
    },
    db::{
        self,
+        custody::{self, CustodyRecord},
        models::{self, RootKeyHistory, RootKeyHistoryId},
        schema::{self},
    },
 };
+
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

 use chrono::Utc;
@@ -60,6 +62,9 @@ pub enum Error {
    #[error("Database transaction error: {0}")]
    DatabaseTransaction(#[from] diesel::result::Error),

+    #[error("Custody storage error: {0}")]
+    Custody(#[from] custody::Error),
+
    #[error("Broken database")]
    BrokenDatabase,

@@ -118,7 +123,12 @@ impl Vault {
            }
        };

-        Ok(Self { db, state, events, unseal_failures: 0 })
+        Ok(Self {
+            db,
+            state,
+            events,
+            unseal_failures: 0,
+        })
    }

    // Exclusive transaction to avoid race condtions if multiple vaults write
@@ -167,13 +177,16 @@ impl Vault {
        }
    }

+    /// Create the root key and take the vault into the unsealed state.
    #[message]
-    pub async fn bootstrap(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
+    pub async fn bootstrap(
+        &mut self,
+        mut seal_key: KeyCell,
+        custody: Option<CustodyRecord>,
+    ) -> Result<(), Error> {
        if !matches!(self.state, State::Unbootstrapped) {
            return Err(Error::AlreadyBootstrapped);
        }
-        let salt = v1::generate_salt();
-        let mut seal_key = derive_key(seal_key_raw, &salt);
        let mut root_key = KeyCell::new_secure_random();

        // Zero nonces are fine because they are one-time
@@ -202,7 +215,7 @@ impl Vault {
                        root_key_encryption_nonce: root_key_nonce.to_vec(),
                        data_encryption_nonce: data_encryption_nonce_bytes.clone(),
                        schema_version: 1,
-                        salt: salt.to_vec(),
+                        salt: v1::generate_salt().to_vec(),
                    })
                    .returning(schema::root_key_history::id)
                    .get_result(&mut *conn)
@@ -213,9 +226,11 @@ impl Vault {
                    .execute(&mut *conn)
                    .await?;

-                Result::<_, diesel::result::Error>::Ok(RootKeyHistoryId::from_raw(
-                    root_key_history_id,
-                ))
+                if let Some(record) = custody.as_ref() {
+                    custody::write_record(&mut *conn, record).await?;
+                }
+
+                Result::<_, Error>::Ok(RootKeyHistoryId::from_raw(root_key_history_id))
            })
            .await?;

@@ -231,7 +246,7 @@ impl Vault {
    }

    #[message]
-    pub async fn try_unseal(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
+    pub async fn try_unseal(&mut self, mut seal_key: KeyCell) -> Result<(), Error> {
        if self.unseal_failures >= MAX_UNSEAL_ATTEMPTS {
            return Err(Error::LockedOut);
        }
@@ -253,13 +268,6 @@ impl Vault {
                .await?
        };

-        let salt = &current_key.salt;
-        let salt = v1::Salt::try_from(salt.as_slice()).map_err(|_| {
-            error!("Broken database: invalid salt for root key");
-            Error::BrokenDatabase
-        })?;
-        let mut seal_key = derive_key(seal_key_raw, &salt);
-
        let mut root_key = SafeCell::new(current_key.ciphertext.clone());

        let nonce =
@@ -442,8 +450,6 @@ impl Vault {
 #[cfg(test)]
 mod tests {
    use crate::actors::GlobalActors;
-    use crate::db::models::RootKeyHistory;
-    use arbiter_crypto::safecell::SafeCellHandle as _;

    use super::*;

@@ -451,8 +457,8 @@ mod tests {
        let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
            .await
            .unwrap();
-        let seal_key = SafeCell::new(b"test-seal-key".to_vec());
-        actor.bootstrap(seal_key).await.unwrap();
+        let seal_key = KeyCell::from([0u8; 32]);
+        actor.bootstrap(seal_key, None).await.unwrap();
        actor
    }

--- a/server/crates/arbiter-server/src/actors/vault_coordinator/mod.rs
+++ b/server/crates/arbiter-server/src/actors/vault_coordinator/mod.rs
@@ -0,0 +1,378 @@
+//! Coordinates the multi-operator ceremonies that create and open the vault.
+//!
+//! The coordinator collects one passphrase per committee member, then hands the
+//! assembled material to [`Vault`] in a single message. It owns no Diesel code:
+//! everything it reads or writes goes through [`db::custody`].
+
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use argon2::RECOMMENDED_SALT_LEN;
+use kameo::{Actor, actor::ActorRef, error::SendError, messages};
+use rand::rngs::SysRng;
+use rand_core::{Rng as _, UnwrapErr};
+
+use crate::{
+    actors::vault::{self, Bootstrap, TryUnseal, Vault},
+    crypto::{KeyCell, derive_key, encryption::v1::Nonce, shamir},
+    db::{
+        self,
+        custody::{self, CustodyRecord, EncryptedShare},
+        models::OperatorId,
+    },
+};
+
+const SHARE_AAD: &[u8] = b"arbiter/shamir-share/v1";
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("An ordinary committee is already being coordinated")]
+    AlreadyBootstrapping,
+    #[error("An unseal is already being coordinated")]
+    AlreadyUnsealing,
+    #[error("Bootstrap is not in progress")]
+    NotBootstrapping,
+    #[error("The operator already contributed")]
+    DuplicateContribution,
+    #[error("The ordinary committee cannot be empty")]
+    EmptyCommittee,
+    #[error("Two-operator committees are unsupported")]
+    UnsupportedCommittee,
+    #[error(
+        "The ordinary committee cannot exceed {} members",
+        shamir::MAX_COMMITTEE_SIZE
+    )]
+    CommitteeTooLarge,
+    #[error("Invalid passphrase")]
+    InvalidPassphrase,
+    #[error("Broken database")]
+    BrokenDatabase,
+    #[error("Shamir error: {0}")]
+    Shamir(String),
+    #[error("Database connection error: {0}")]
+    DatabaseConnection(#[from] db::PoolError),
+    #[error("Custody storage error: {0}")]
+    Custody(#[from] custody::Error),
+    #[error("Encryption error")]
+    Encryption,
+    #[error("The vault is already bootstrapped")]
+    AlreadyBootstrapped,
+    #[error("Vault error")]
+    Vault,
+}
+
+/// Passphrases gathered so far, in contribution order.
+///
+/// A `Vec` rather than a map because [`SafeCell`] values are neither cloneable
+/// nor hashable, and a committee holds at most
+/// [`shamir::MAX_COMMITTEE_SIZE`] of them.
+#[derive(Default)]
+struct Contributions(Vec<(OperatorId, SafeCell<Vec<u8>>)>);
+
+impl Contributions {
+    fn contains(&self, operator_id: OperatorId) -> bool {
+        self.0.iter().any(|(id, _)| *id == operator_id)
+    }
+
+    fn put(&mut self, operator_id: OperatorId, passphrase: SafeCell<Vec<u8>>) {
+        match self.0.iter_mut().find(|(id, _)| *id == operator_id) {
+            Some(slot) => slot.1 = passphrase,
+            None => self.0.push((operator_id, passphrase)),
+        }
+    }
+
+    const fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    fn operators(&self) -> Vec<OperatorId> {
+        self.0.iter().map(|(id, _)| *id).collect()
+    }
+}
+
+enum CoordinatorState {
+    Idle,
+    Bootstrapping {
+        /// The operator that declared the committee. Only they may re-declare
+        /// it, which is the way out of a ceremony the others never finish.
+        declarer: OperatorId,
+        declared_count: usize,
+        contributions: Contributions,
+        retryable: bool,
+    },
+    Unsealing {
+        threshold: usize,
+        contributions: Contributions,
+        retryable: bool,
+    },
+}
+
+#[derive(Actor)]
+pub struct VaultCoordinator {
+    db: db::DatabasePool,
+    vault: ActorRef<Vault>,
+    state: CoordinatorState,
+}
+
+impl VaultCoordinator {
+    pub const fn new(db: db::DatabasePool, vault: ActorRef<Vault>) -> Self {
+        Self {
+            db,
+            vault,
+            state: CoordinatorState::Idle,
+        }
+    }
+}
+
+/// Explain why a committee size was rejected.
+const fn committee_error(declared_count: usize) -> Error {
+    match declared_count {
+        0 => Error::EmptyCommittee,
+        2 => Error::UnsupportedCommittee,
+        _ => Error::CommitteeTooLarge,
+    }
+}
+
+fn encrypt_share(
+    passphrase: &mut SafeCell<Vec<u8>>,
+    share: &[u8],
+) -> Result<EncryptedShare, Error> {
+    let mut salt = [0u8; RECOMMENDED_SALT_LEN];
+    UnwrapErr(SysRng).fill_bytes(&mut salt);
+
+    let nonce = Nonce::default();
+    let ciphertext = derive_key(passphrase, &salt)
+        .encrypt(&nonce, SHARE_AAD, share)
+        .map_err(|_| Error::Encryption)?;
+
+    Ok(EncryptedShare {
+        ciphertext,
+        nonce: nonce.to_vec(),
+        salt: salt.to_vec(),
+    })
+}
+
+fn decrypt_share(
+    passphrase: &mut SafeCell<Vec<u8>>,
+    share: EncryptedShare,
+) -> Result<SafeCell<Vec<u8>>, Error> {
+    let nonce = Nonce::try_from(share.nonce.as_slice()).map_err(|()| Error::BrokenDatabase)?;
+
+    let mut buffer = SafeCell::new(share.ciphertext);
+    derive_key(passphrase, &share.salt)
+        .decrypt_in_place(&nonce, SHARE_AAD, &mut buffer)
+        .map_err(|_| Error::InvalidPassphrase)?;
+
+    Ok(buffer)
+}
+
+const fn bootstrap_error(error: &SendError<Bootstrap, vault::Error>) -> Error {
+    match error {
+        SendError::HandlerError(vault::Error::AlreadyBootstrapped) => Error::AlreadyBootstrapped,
+        _ => Error::Vault,
+    }
+}
+
+/// Build the custody record and hand it to the vault, which stores it in the
+/// same transaction as the root key.
+async fn finalize_bootstrap(
+    vault: &ActorRef<Vault>,
+    contributions: &mut Contributions,
+) -> Result<(), Error> {
+    let total = contributions.len();
+    let threshold = shamir::shamir_threshold(total).ok_or_else(|| committee_error(total))?;
+
+    let mut seal_key = KeyCell::new_secure_random();
+    let mut shares = shamir::split_key(threshold, total, &mut seal_key, UnwrapErr(SysRng))
+        .map_err(|error| Error::Shamir(error.to_string()))?;
+
+    if shares.len() < total {
+        return Err(Error::Shamir("missing share for operator".to_owned()));
+    }
+
+    let mut encrypted = Vec::with_capacity(total);
+    for ((operator_id, passphrase), share) in contributions.0.iter_mut().zip(shares.iter_mut()) {
+        let share = share.read_inline(|share| encrypt_share(passphrase, share))?;
+        encrypted.push((*operator_id, share));
+    }
+
+    vault
+        .ask(Bootstrap {
+            seal_key,
+            custody: Some(CustodyRecord {
+                threshold,
+                shares: encrypted,
+            }),
+        })
+        .await
+        .map_err(|error| bootstrap_error(&error))
+}
+
+/// Reconstruct the seal key from the contributed passphrases and unseal.
+async fn finalize_unseal(
+    db: &db::DatabasePool,
+    vault: &ActorRef<Vault>,
+    threshold: usize,
+    contributions: &mut Contributions,
+) -> Result<(), Error> {
+    let stored = {
+        let mut conn = db.get().await?;
+        custody::shares(&mut conn, &contributions.operators()).await?
+    };
+
+    let mut plaintext = Vec::with_capacity(stored.len());
+    for ((_, passphrase), share) in contributions.0.iter_mut().zip(stored) {
+        plaintext.push(decrypt_share(passphrase, share)?);
+    }
+
+    let seal_key = shamir::combine_shares(threshold, &mut plaintext)
+        .map_err(|error| Error::Shamir(error.to_string()))?;
+
+    vault
+        .ask(TryUnseal { seal_key })
+        .await
+        .map_err(|_| Error::Vault)
+}
+
+#[messages]
+impl VaultCoordinator {
+    /// Announce how many operators will contribute to the bootstrap.
+    ///
+    /// The declaring operator may re-declare to restart the ceremony; that is
+    /// the only way to release a committee whose members never all show up.
+    #[message]
+    pub fn start_bootstrap(
+        &mut self,
+        operator_id: OperatorId,
+        declared_count: usize,
+    ) -> Result<(), Error> {
+        if shamir::shamir_threshold(declared_count).is_none() {
+            return Err(committee_error(declared_count));
+        }
+
+        match &self.state {
+            CoordinatorState::Unsealing { .. } => return Err(Error::AlreadyUnsealing),
+            CoordinatorState::Bootstrapping { declarer, .. } if *declarer != operator_id => {
+                return Err(Error::AlreadyBootstrapping);
+            }
+            CoordinatorState::Bootstrapping { .. } | CoordinatorState::Idle => {}
+        }
+
+        self.state = CoordinatorState::Bootstrapping {
+            declarer: operator_id,
+            declared_count,
+            contributions: Contributions::default(),
+            retryable: false,
+        };
+        Ok(())
+    }
+
+    #[message]
+    pub async fn contribute_bootstrap(
+        &mut self,
+        operator_id: OperatorId,
+        passphrase: SafeCell<Vec<u8>>,
+    ) -> Result<bool, Error> {
+        let CoordinatorState::Bootstrapping {
+            declared_count,
+            contributions,
+            retryable,
+            ..
+        } = &mut self.state
+        else {
+            return Err(Error::NotBootstrapping);
+        };
+
+        if contributions.contains(operator_id) && !*retryable {
+            return Err(Error::DuplicateContribution);
+        }
+        contributions.put(operator_id, passphrase);
+        *retryable = false;
+
+        if contributions.len() < *declared_count {
+            return Ok(false);
+        }
+
+        let state = std::mem::replace(&mut self.state, CoordinatorState::Idle);
+        let CoordinatorState::Bootstrapping {
+            declarer,
+            declared_count,
+            mut contributions,
+            ..
+        } = state
+        else {
+            unreachable!("state was matched as Bootstrapping above")
+        };
+
+        match finalize_bootstrap(&self.vault, &mut contributions).await {
+            Ok(()) => Ok(true),
+            Err(error) => {
+                self.state = CoordinatorState::Bootstrapping {
+                    declarer,
+                    declared_count,
+                    contributions,
+                    retryable: true,
+                };
+                Err(error)
+            }
+        }
+    }
+
+    #[message]
+    pub async fn contribute_unseal(
+        &mut self,
+        operator_id: OperatorId,
+        passphrase: SafeCell<Vec<u8>>,
+    ) -> Result<bool, Error> {
+        if matches!(self.state, CoordinatorState::Idle) {
+            let threshold = {
+                let mut conn = self.db.get().await?;
+                custody::threshold(&mut conn).await?
+            };
+            self.state = CoordinatorState::Unsealing {
+                threshold,
+                contributions: Contributions::default(),
+                retryable: false,
+            };
+        }
+
+        let CoordinatorState::Unsealing {
+            threshold,
+            contributions,
+            retryable,
+        } = &mut self.state
+        else {
+            return Err(Error::AlreadyBootstrapping);
+        };
+
+        if contributions.contains(operator_id) && !*retryable {
+            return Err(Error::DuplicateContribution);
+        }
+        contributions.put(operator_id, passphrase);
+        *retryable = false;
+
+        if contributions.len() < *threshold {
+            return Ok(false);
+        }
+
+        let state = std::mem::replace(&mut self.state, CoordinatorState::Idle);
+        let CoordinatorState::Unsealing {
+            threshold,
+            mut contributions,
+            ..
+        } = state
+        else {
+            unreachable!("state was matched as Unsealing above")
+        };
+
+        match finalize_unseal(&self.db, &self.vault, threshold, &mut contributions).await {
+            Ok(()) => Ok(true),
+            Err(error) => {
+                self.state = CoordinatorState::Unsealing {
+                    threshold,
+                    contributions,
+                    retryable: true,
+                };
+                Err(error)
+            }
+        }
+    }
+}
--- a/server/crates/arbiter-server/src/crypto/encryption/v1.rs
+++ b/server/crates/arbiter-server/src/crypto/encryption/v1.rs
@@ -61,12 +61,11 @@ mod tests {
    #[test]
    fn derive_seal_key_deterministic() {
        static PASSWORD: &[u8] = b"password";
-        let password = SafeCell::new(PASSWORD.to_vec());
-        let password2 = SafeCell::new(PASSWORD.to_vec());
+        let mut password = SafeCell::new(PASSWORD.to_vec());
        let salt = generate_salt();

-        let mut key1 = derive_key(password, &salt);
-        let mut key2 = derive_key(password2, &salt);
+        let mut key1 = derive_key(&mut password, &salt);
+        let mut key2 = derive_key(&mut password, &salt);

        let key1_reader = key1.0.read();
        let key2_reader = key2.0.read();
@@ -77,10 +76,10 @@ mod tests {
    #[test]
    fn successful_derive() {
        static PASSWORD: &[u8] = b"password";
-        let password = SafeCell::new(PASSWORD.to_vec());
+        let mut password = SafeCell::new(PASSWORD.to_vec());
        let salt = generate_salt();

-        let mut key = derive_key(password, &salt);
+        let mut key = derive_key(&mut password, &salt);
        let key_reader = key.0.read();

        assert_ne!(key_reader.as_slice(), &[0u8; 32][..]);
--- a/server/crates/arbiter-server/src/crypto/integrity/v1.rs
+++ b/server/crates/arbiter-server/src/crypto/integrity/v1.rs
@@ -215,9 +215,9 @@ mod tests {
            GlobalActors,
            vault::{Bootstrap, Vault},
        },
+        crypto::KeyCell,
        db::{self, schema},
    };
-    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

    use super::{Error, Integrable, sign_entity, verify_entity};
    #[derive(Clone, arbiter_macros::Hashable)]
@@ -237,7 +237,8 @@ mod tests {
        );
        actor
            .ask(Bootstrap {
-                seal_key_raw: SafeCell::new(b"integrity-test-seal-key".to_vec()),
+                seal_key: KeyCell::from([0u8; 32]),
+                custody: None,
            })
            .await
            .unwrap();
--- a/server/crates/arbiter-server/src/crypto/mod.rs
+++ b/server/crates/arbiter-server/src/crypto/mod.rs
@@ -1,5 +1,5 @@
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
-use encryption::v1::{Nonce, Salt};
+use encryption::v1::Nonce;

 use argon2::{Algorithm, Argon2};
 use chacha20poly1305::{
@@ -13,6 +13,7 @@ use rand::{

 pub mod encryption;
 pub mod integrity;
+pub mod shamir;

 pub struct KeyCell(pub SafeCell<Key>);
 impl From<SafeCell<Key>> for KeyCell {
@@ -20,6 +21,16 @@ impl From<SafeCell<Key>> for KeyCell {
        Self(value)
    }
 }
+
+impl From<[u8; 32]> for KeyCell {
+    fn from(bytes: [u8; 32]) -> Self {
+        let cell = SafeCell::new_inline(|key: &mut Key| {
+            key.copy_from_slice(&bytes);
+        });
+        Self(cell)
+    }
+}
+
 impl TryFrom<SafeCell<Vec<u8>>> for KeyCell {
    type Error = ();

@@ -58,6 +69,7 @@ impl KeyCell {
        let buffer = buffer.as_mut();
        cipher.encrypt_in_place(nonce, associated_data, buffer)
    }
+
    pub fn decrypt_in_place(
        &mut self,
        nonce: &Nonce,
@@ -93,8 +105,11 @@ impl KeyCell {
    }
 }

-/// Derive a fixed-length key from the password using Argon2id, which is designed for password hashing and key derivation.
-pub fn derive_key(mut password: SafeCell<Vec<u8>>, salt: &Salt) -> KeyCell {
+/// Derive a fixed-length key from a passphrase using Argon2id.
+///
+/// The passphrase is borrowed so that callers can keep it in protected memory
+/// and reuse it across retries instead of handing over a copy.
+pub fn derive_key(password: &mut SafeCell<Vec<u8>>, salt: &[u8]) -> KeyCell {
    let params = {
        #[cfg(debug_assertions)]
        {
@@ -132,11 +147,11 @@ mod tests {
    #[test]
    fn encrypt_decrypt() {
        static PASSWORD: &[u8] = b"password";
-        let password = SafeCell::new(PASSWORD.to_vec());
+        let mut password = SafeCell::new(PASSWORD.to_vec());
        let salt = generate_salt();

-        let mut key = derive_key(password, &salt);
-        let nonce = Nonce(*b"unique nonce 123 1231233"); // 24 bytes for XChaCha20Poly1305
+        let mut key = derive_key(&mut password, &salt);
+        let nonce = Nonce(*b"unique nonce 123 1231233");
        let associated_data = b"associated data";
        let mut buffer = b"secret data".to_vec();

--- a/server/crates/arbiter-server/src/crypto/shamir.rs
+++ b/server/crates/arbiter-server/src/crypto/shamir.rs
@@ -0,0 +1,221 @@
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use rand_core::CryptoRng;
+use vsss_rs::Gf256;
+
+use crate::crypto::KeyCell;
+
+/// GF(256) addresses shares by a non-zero byte, so no committee can exceed 255.
+pub const MAX_COMMITTEE_SIZE: usize = 255;
+
+/// Errors returned by Shamir split/combine operations.
+#[derive(Debug, thiserror::Error)]
+pub enum ShamirError {
+    #[error("failed to split key: {0}")]
+    Split(String),
+    #[error("failed to combine shares: {0}")]
+    Combine(String),
+}
+
+/// Return the required threshold for a Shamir share pool of `committee_size`.
+///
+/// A pool of two is rejected: a majority of two is two, which gives each holder
+/// a veto over every unseal without giving either one recovery. That rejects no
+/// supported committee, because a two-operator vault must carry at least one
+/// recovery share and so never splits into a pool of two -- see
+/// `docs/ARCHITECTURE.md` 3.9.
+#[expect(
+    clippy::integer_division,
+    reason = "majority thresholds use integer arithmetic"
+)]
+#[must_use]
+pub const fn shamir_threshold(committee_size: usize) -> Option<usize> {
+    match committee_size {
+        0 | 2 => None,
+        size if size > MAX_COMMITTEE_SIZE => None,
+        1 => Some(1),
+        size => Some(size / 2 + 1),
+    }
+}
+
+/// Split a seal key into `total` shares, `threshold` of which reconstruct it.
+pub fn split_key(
+    threshold: usize,
+    total: usize,
+    key: &mut KeyCell,
+    rng: impl CryptoRng,
+) -> Result<Vec<SafeCell<Vec<u8>>>, ShamirError> {
+    if total == 0 || threshold == 0 || threshold > total || total == 2 || total > MAX_COMMITTEE_SIZE
+    {
+        return Err(ShamirError::Split(
+            "unsupported committee parameters".to_owned(),
+        ));
+    }
+
+    // Nothing to interpolate when one share suffices.
+    if threshold == 1 {
+        return Ok(key.0.read_inline(|key| {
+            std::iter::repeat_with(|| SafeCell::new(key.as_slice().to_vec()))
+                .take(total)
+                .collect()
+        }));
+    }
+
+    key.0.read_inline(|key| {
+        let key: &[u8; 32] = key
+            .as_slice()
+            .try_into()
+            .map_err(|_| ShamirError::Split("unexpected seal key length".to_owned()))?;
+
+        Gf256::split_array(threshold, total, key, rng)
+            .map(|shares| shares.into_iter().map(SafeCell::new).collect())
+            .map_err(|error| ShamirError::Split(format!("{error:?}")))
+    })
+}
+
+/// Combine shares back into the seal key.
+///
+/// `threshold` comes from storage rather than from the shapes of the shares:
+/// a one-of-one committee stores the key verbatim, and telling that apart by
+/// share length alone would misread any Shamir share that happened to be key
+/// sized.
+pub fn combine_shares(
+    threshold: usize,
+    shares: &mut [SafeCell<Vec<u8>>],
+) -> Result<KeyCell, ShamirError> {
+    if threshold == 0 {
+        return Err(ShamirError::Combine("threshold is zero".to_owned()));
+    }
+    if shares.len() < threshold {
+        return Err(ShamirError::Combine(
+            "not enough shares supplied".to_owned(),
+        ));
+    }
+
+    // Mirror of the one-of-one case in [`split_key`]: the share is the key.
+    if threshold == 1 {
+        let share = shares
+            .first_mut()
+            .ok_or_else(|| ShamirError::Combine("no shares supplied".to_owned()))?;
+        return reconstructed_key(share.read_inline(|share| SafeCell::new(share.clone())));
+    }
+
+    let mut gathered = SafeCell::new(Vec::with_capacity(shares.len()));
+    for share in shares.iter_mut() {
+        share.read_inline(|share| {
+            gathered.write_inline(|gathered| gathered.push(share.clone()));
+        });
+    }
+
+    let combined = gathered.read_inline(|gathered| {
+        Gf256::combine_array(gathered.as_slice())
+            .map(SafeCell::new)
+            .map_err(|error| ShamirError::Combine(format!("{error:?}")))
+    })?;
+
+    reconstructed_key(combined)
+}
+
+fn reconstructed_key(bytes: SafeCell<Vec<u8>>) -> Result<KeyCell, ShamirError> {
+    KeyCell::try_from(bytes)
+        .map_err(|()| ShamirError::Combine("unexpected reconstructed key length".to_owned()))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{MAX_COMMITTEE_SIZE, combine_shares, shamir_threshold, split_key};
+    use crate::crypto::KeyCell;
+    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+    use rand::rngs::SysRng;
+    use rand_core::UnwrapErr;
+    use rstest::rstest;
+
+    fn key_bytes(mut key: KeyCell) -> [u8; 32] {
+        key.0.read_inline(|key| {
+            let mut bytes = [0u8; 32];
+            bytes.copy_from_slice(key.as_slice());
+            bytes
+        })
+    }
+
+    fn select(shares: &mut [SafeCell<Vec<u8>>], indexes: &[usize]) -> Vec<SafeCell<Vec<u8>>> {
+        indexes
+            .iter()
+            .filter_map(|index| {
+                shares
+                    .get_mut(*index)
+                    .map(|share| share.read_inline(|share| SafeCell::new(share.clone())))
+            })
+            .collect()
+    }
+
+    #[rstest]
+    #[case(&[0, 1])]
+    #[case(&[0, 2])]
+    #[case(&[1, 2])]
+    fn threshold_shares_reconstruct_fixed_key(#[case] indexes: &[usize]) {
+        let expected = [9_u8; 32];
+        let mut key = KeyCell::from(expected);
+        let rng = UnwrapErr(SysRng);
+        let mut shares = split_key(2, 3, &mut key, rng).expect("split should succeed");
+        let mut selected = select(&mut shares, indexes);
+        let combined = combine_shares(2, &mut selected).expect("combine should succeed");
+        assert_eq!(key_bytes(combined), expected);
+    }
+
+    #[test]
+    fn one_of_one_round_trips_a_fixed_size_key() {
+        let expected = [7_u8; 32];
+        let mut key = KeyCell::from(expected);
+        let rng = UnwrapErr(SysRng);
+        let mut shares = split_key(1, 1, &mut key, rng).expect("split should succeed");
+        let combined = combine_shares(1, &mut shares).expect("combine should succeed");
+        assert_eq!(key_bytes(combined), expected);
+    }
+
+    #[test]
+    fn fewer_shares_than_threshold_is_rejected() {
+        let mut key = KeyCell::from([3_u8; 32]);
+        let rng = UnwrapErr(SysRng);
+        let mut shares = split_key(3, 5, &mut key, rng).expect("split should succeed");
+        let mut selected = select(&mut shares, &[0, 1]);
+        assert!(
+            combine_shares(3, &mut selected).is_err(),
+            "two of three shares must not reconstruct the key"
+        );
+    }
+
+    #[rstest]
+    #[case(0, None)]
+    #[case(1, Some(1))]
+    #[case(2, None)]
+    #[case(3, Some(2))]
+    #[case(4, Some(3))]
+    #[case(MAX_COMMITTEE_SIZE, Some(128))]
+    #[case(MAX_COMMITTEE_SIZE + 1, None)]
+    fn committee_threshold_is_a_majority(
+        #[case] committee_size: usize,
+        #[case] expected: Option<usize>,
+    ) {
+        assert_eq!(shamir_threshold(committee_size), expected);
+    }
+
+    #[test]
+    fn oversized_committee_is_rejected_by_split() {
+        let mut key = KeyCell::from([1_u8; 32]);
+        let rng = UnwrapErr(SysRng);
+        assert!(
+            split_key(129, MAX_COMMITTEE_SIZE + 1, &mut key, rng).is_err(),
+            "committees above the GF(256) share limit must be rejected"
+        );
+    }
+
+    #[test]
+    fn two_operator_committee_is_explicitly_unsupported() {
+        let mut key = KeyCell::from([7_u8; 32]);
+        let rng = UnwrapErr(SysRng);
+        assert!(
+            split_key(2, 2, &mut key, rng).is_err(),
+            "two-operator committees must be rejected"
+        );
+    }
+}
--- a/server/crates/arbiter-server/src/db/custody.rs
+++ b/server/crates/arbiter-server/src/db/custody.rs
@@ -0,0 +1,137 @@
+//! Storage for Shamir custody material: the reconstruction threshold and the
+//! per-operator encrypted shares of the vault seal key.
+//!
+//! The queries live here so that the actors above hold no Diesel code of their
+//! own. Every one of them borrows the caller's connection instead of taking one
+//! from the pool, which is what lets the vault write custody material inside
+//! the same transaction that stores the root key.
+
+use std::collections::HashMap;
+
+use diesel::{ExpressionMethods as _, QueryDsl};
+use diesel_async::RunQueryDsl;
+
+use crate::db::{
+    self,
+    models::{OperatorId, SqliteTimestamp},
+    schema,
+};
+
+/// One Shamir share, encrypted under a key derived from its operator's passphrase.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct EncryptedShare {
+    pub ciphertext: Vec<u8>,
+    pub nonce: Vec<u8>,
+    pub salt: Vec<u8>,
+}
+
+/// Everything a bootstrap persists about custody, written as a single unit.
+#[derive(Debug)]
+pub struct CustodyRecord {
+    pub threshold: usize,
+    pub shares: Vec<(OperatorId, EncryptedShare)>,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Database query error: {0}")]
+    Query(#[from] diesel::result::Error),
+    #[error("Stored committee threshold is missing or out of range")]
+    BrokenThreshold,
+    #[error("Custody settings row is missing")]
+    MissingSettings,
+    #[error("No share stored for operator {0:?}")]
+    MissingShare(OperatorId),
+}
+
+/// Persist threshold and shares on the caller's connection, joining any
+/// transaction the caller has already opened.
+pub async fn write_record(
+    conn: &mut db::DatabaseConnection,
+    record: &CustodyRecord,
+) -> Result<(), Error> {
+    let threshold = i32::try_from(record.threshold).map_err(|_| Error::BrokenThreshold)?;
+
+    // SQLite has no batch form for REPLACE INTO in diesel, so the rows go
+    // in one at a time. The caller's transaction still makes them atomic.
+    let now = SqliteTimestamp::now();
+    for (operator_id, share) in &record.shares {
+        diesel::replace_into(schema::operator::table)
+            .values((
+                schema::operator::id.eq(Some(*operator_id)),
+                schema::operator::share.eq(&share.ciphertext),
+                schema::operator::share_nonce.eq(&share.nonce),
+                schema::operator::share_salt.eq(&share.salt),
+                schema::operator::created_at.eq(now.clone()),
+                schema::operator::updated_at.eq(now.clone()),
+            ))
+            .execute(&mut *conn)
+            .await?;
+    }
+
+    let updated = diesel::update(schema::arbiter_settings::table)
+        .set(schema::arbiter_settings::shamir_threshold.eq(Some(threshold)))
+        .execute(&mut *conn)
+        .await?;
+    if updated != 1 {
+        return Err(Error::MissingSettings);
+    }
+
+    Ok(())
+}
+
+/// Number of shares required to reconstruct the seal key.
+pub async fn threshold(conn: &mut db::DatabaseConnection) -> Result<usize, Error> {
+    let stored: Option<i32> = schema::arbiter_settings::table
+        .select(schema::arbiter_settings::shamir_threshold)
+        .first(conn)
+        .await?;
+
+    stored
+        .and_then(|value| usize::try_from(value).ok())
+        .filter(|threshold| *threshold > 0)
+        .ok_or(Error::BrokenThreshold)
+}
+
+/// Load the shares of `operators` in one query, in the order requested.
+pub async fn shares(
+    conn: &mut db::DatabaseConnection,
+    operators: &[OperatorId],
+) -> Result<Vec<EncryptedShare>, Error> {
+    /// (id, then the three columns that make up [`EncryptedShare`])
+    type ShareRow = (Option<OperatorId>, Vec<u8>, Vec<u8>, Vec<u8>);
+
+    let wanted: Vec<Option<OperatorId>> = operators.iter().copied().map(Some).collect();
+
+    let rows: Vec<ShareRow> = schema::operator::table
+        .filter(schema::operator::id.eq_any(wanted))
+        .select((
+            schema::operator::id,
+            schema::operator::share,
+            schema::operator::share_nonce,
+            schema::operator::share_salt,
+        ))
+        .load(conn)
+        .await?;
+
+    let mut found: HashMap<OperatorId, EncryptedShare> = rows
+        .into_iter()
+        .filter_map(|(id, ciphertext, nonce, salt)| {
+            id.map(|id| {
+                (
+                    id,
+                    EncryptedShare {
+                        ciphertext,
+                        nonce,
+                        salt,
+                    },
+                )
+            })
+        })
+        .collect();
+
+    operators
+        .iter()
+        .map(|id| found.remove(id).ok_or(Error::MissingShare(*id)))
+        .collect()
+}
--- a/server/crates/arbiter-server/src/db/mod.rs
+++ b/server/crates/arbiter-server/src/db/mod.rs
@@ -8,6 +8,7 @@ use diesel_migrations::{EmbeddedMigrations, MigrationHarness, embed_migrations};
 use thiserror::Error;
 use tracing::info;

+pub mod custody;
 pub mod models;
 pub mod schema;

@@ -154,3 +155,39 @@ pub async fn create_test_pool() -> DatabasePool {
        .await
        .expect("Failed to create test database pool")
 }
+
+#[cfg(test)]
+mod tests {
+    use diesel::{ExpressionMethods as _, result::DatabaseErrorKind};
+    use diesel_async::RunQueryDsl as _;
+
+    use super::*;
+
+    #[tokio::test]
+    async fn operator_share_salt_must_be_supplied_by_application() {
+        let pool = create_test_pool().await;
+        let mut conn = pool.get().await.expect("pool connection");
+
+        let operator_id = diesel::insert_into(schema::operator_identity::table)
+            .values(schema::operator_identity::public_key.eq(vec![1]))
+            .returning(schema::operator_identity::id)
+            .get_result::<i32>(&mut conn)
+            .await
+            .expect("insert operator identity");
+
+        let error = diesel::insert_into(schema::operator::table)
+            .values((
+                schema::operator::id.eq(operator_id),
+                schema::operator::share.eq(vec![2]),
+                schema::operator::share_nonce.eq(vec![3]),
+            ))
+            .execute(&mut conn)
+            .await
+            .expect_err("operator insert without an application-generated salt must fail");
+
+        assert!(matches!(
+            error,
+            diesel::result::Error::DatabaseError(DatabaseErrorKind::NotNullViolation, _)
+        ));
+    }
+}
--- a/server/crates/arbiter-server/src/db/models.rs
+++ b/server/crates/arbiter-server/src/db/models.rs
@@ -110,6 +110,18 @@ pub mod types {
                    ToSql::<Integer, Sqlite>::to_sql(&self.0, out)
                }
            }
+
+            impl arbiter_crypto::hashing::Hashable for $name {
+                fn hash<H: arbiter_crypto::hashing::Digest>(&self, hasher: &mut H) {
+                    arbiter_crypto::hashing::Hashable::hash(&self.0, hasher);
+                }
+            }
+
+            impl crate::crypto::integrity::v1::IntoId for $name {
+                fn into_id(self) -> Vec<u8> {
+                    crate::crypto::integrity::v1::IntoId::into_id(self.0)
+                }
+            }
        };
    }

@@ -203,6 +215,7 @@ pub struct ArbiterSettings {
    pub id: i32,
    pub root_key_id: Option<i32>, // references root_key_history.id
    pub tls_id: Option<i32>,      // references tls_history.id
+    pub shamir_threshold: Option<i32>,
 }

 #[derive(Models, Queryable, Debug, Insertable, Selectable)]
@@ -285,6 +298,7 @@ pub struct Operator {
    pub id: OperatorId,
    pub share: Vec<u8>,
    pub share_nonce: Vec<u8>,
+    pub share_salt: Vec<u8>,
    pub created_at: SqliteTimestamp,
    pub updated_at: SqliteTimestamp,
 }
--- a/server/crates/arbiter-server/src/db/schema.rs
+++ b/server/crates/arbiter-server/src/db/schema.rs
@@ -17,6 +17,7 @@ diesel::table! {
        id -> Integer,
        root_key_id -> Nullable<Integer>,
        tls_id -> Nullable<Integer>,
+        shamir_threshold -> Nullable<Integer>,
    }
 }

@@ -157,6 +158,7 @@ diesel::table! {
        id -> Nullable<Integer>,
        share -> Binary,
        share_nonce -> Binary,
+        share_salt -> Binary,
        created_at -> Integer,
        updated_at -> Integer,
    }
--- a/server/crates/arbiter-server/src/evm/mod.rs
+++ b/server/crates/arbiter-server/src/evm/mod.rs
@@ -502,7 +502,6 @@ impl Engine {
 #[cfg(test)]
 mod tests {
    use alloy::primitives::{Address, Bytes, U256, address};
-    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
    use chrono::{Duration, Utc};
    use diesel::{SelectableHelper, insert_into};
    use diesel_async::RunQueryDsl;
@@ -510,6 +509,7 @@ mod tests {
    use rstest::rstest;

    use crate::actors::{GlobalActors, vault::{Bootstrap, Vault}};
+    use crate::crypto::KeyCell;
    use crate::crypto::integrity;
    use crate::db::{
        self, DatabaseConnection,
@@ -772,7 +772,8 @@ mod tests {
        );
        actor
            .ask(Bootstrap {
-                seal_key_raw: SafeCell::new(b"integrity-test-seal-key".to_vec()),
+                seal_key: KeyCell::from([0u8; 32]),
+                custody: None,
            })
            .await
            .unwrap();
--- a/server/crates/arbiter-server/src/grpc/operator.rs
+++ b/server/crates/arbiter-server/src/grpc/operator.rs
@@ -1,11 +1,10 @@
 use crate::{
    grpc::request_tracker::RequestTracker,
-    peers::operator::{OutOfBand, OperatorConnection, OperatorSession},
+    peers::operator::{OperatorConnection, OperatorSession, OutOfBand},
 };
 use arbiter_proto::{
    proto::operator::{
-        OperatorRequest, OperatorResponse,
-        operator_request::Payload as OperatorRequestPayload,
+        OperatorRequest, OperatorResponse, operator_request::Payload as OperatorRequestPayload,
        operator_response::Payload as OperatorResponsePayload,
    },
    transport::{Error as TransportError, Receiver, Sender, grpc::GrpcBi},
@@ -111,6 +110,9 @@ async fn dispatch_inner(
        OperatorRequestPayload::Vault(req) => vault::dispatch(actor, req).await,
        OperatorRequestPayload::Evm(req) => evm::dispatch(actor, req).await,
        OperatorRequestPayload::SdkClient(req) => sdk_client::dispatch(actor, req).await,
+        OperatorRequestPayload::Governance(_) => {
+            Err(Status::permission_denied(stringify!(Governance)))
+        }
        OperatorRequestPayload::Auth(..) => {
            warn!("Unsupported post-auth operator auth request");
            Err(Status::invalid_argument("Unsupported operator request"))
--- a/server/crates/arbiter-server/src/grpc/operator/vault.rs
+++ b/server/crates/arbiter-server/src/grpc/operator/vault.rs
@@ -3,7 +3,6 @@ use crate::{
    peers::operator::{OperatorSession, session::handlers::HandleQueryVaultState},
 };
 use arbiter_proto::{
-    proto::shared::VaultState as ProtoVaultState,
    proto::operator::{
        operator_response::Payload as OperatorResponsePayload,
        vault::{
@@ -11,6 +10,7 @@ use arbiter_proto::{
            response::Payload as VaultResponsePayload,
        },
    },
+    proto::shared::VaultState as ProtoVaultState,
 };

 use kameo::actor::ActorRef;
@@ -33,11 +33,11 @@ pub(super) async fn dispatch(

    match payload {
        VaultRequestPayload::QueryState(()) => handle_query_vault_state(actor).await,
-        VaultRequestPayload::Unseal(_) | VaultRequestPayload::Bootstrap(_) => {
-            Err(Status::permission_denied(
-                "Vault is already unsealed; unseal/bootstrap not permitted in session",
-            ))
-        }
+        VaultRequestPayload::Unseal(_)
+        | VaultRequestPayload::Bootstrap(_)
+        | VaultRequestPayload::Rekey(_) => Err(Status::permission_denied(
+            "Vault is already unsealed; unseal/bootstrap not permitted in session",
+        )),
    }
 }

--- a/server/crates/arbiter-server/src/grpc/operator/vault_gate/inbound.rs
+++ b/server/crates/arbiter-server/src/grpc/operator/vault_gate/inbound.rs
@@ -1,14 +1,17 @@
 use crate::{
+    crypto::shamir,
    grpc::{Convert, TryConvert},
    peers::operator::vault_gate::{
-        self as vault_gate, HandleBootstrapEncryptedKey, HandleHandshake, HandleUnsealEncryptedKey,
+        self as vault_gate, HandleBootstrapEncryptedKey, HandleContributeBootstrapPassphrase,
+        HandleContributeUnsealPassphrase, HandleDeclareCommittee, HandleHandshake,
+        HandleUnsealEncryptedKey,
    },
 };
 use arbiter_proto::proto::operator::{
    operator_request::Payload as OperatorRequestPayload,
    vault::{
        self as proto_vault,
-        bootstrap::{self as proto_bootstrap},
+        bootstrap::{self as proto_bootstrap, request::Payload as BootstrapRequestPayload},
        request::Payload as VaultRequestPayload,
        unseal::{self as proto_unseal, request::Payload as UnsealRequestPayload},
    },
@@ -50,6 +53,7 @@ impl TryConvert for VaultRequestPayload {
            Self::QueryState(()) => Ok(vault_gate::Inbound::HandleVaultState),
            Self::Unseal(req) => req.try_convert(),
            Self::Bootstrap(req) => req.try_convert(),
+            Self::Rekey(_) => Err(Status::unimplemented("Vault re-key is not available")),
        }
    }
 }
@@ -73,6 +77,16 @@ impl TryConvert for UnsealRequestPayload {
        match self {
            Self::Start(start) => start.try_convert(),
            Self::EncryptedKey(key) => Ok(key.convert()),
+            Self::ContributePassphrase(passphrase) => {
+                Ok(vault_gate::Inbound::HandleContributeUnsealPassphrase(
+                    HandleContributeUnsealPassphrase {
+                        passphrase: passphrase.passphrase,
+                    },
+                ))
+            }
+            Self::ContributeRecoveryPassphrase(_) => Err(Status::unimplemented(
+                "Recovery operator contributions are not available",
+            )),
        }
    }
 }
@@ -107,12 +121,52 @@ impl TryConvert for proto_bootstrap::Request {
    type Error = Status;

    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
-        self.encrypted_key
-            .ok_or_else(|| Status::invalid_argument("Missing bootstrap encrypted key"))?
+        self.payload
+            .ok_or_else(|| Status::invalid_argument("Missing bootstrap payload"))?
            .try_convert()
    }
 }

+impl TryConvert for BootstrapRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            Self::EncryptedKey(key) => key.try_convert(),
+            Self::DeclareCommittee(dc) => {
+                if dc.recovery_count != 0 {
+                    return Err(Status::unimplemented(
+                        "Recovery operator contributions are not available",
+                    ));
+                }
+                let count = usize::try_from(dc.count)
+                    .ok()
+                    .filter(|count| *count <= shamir::MAX_COMMITTEE_SIZE)
+                    .ok_or_else(|| {
+                        Status::invalid_argument(format!(
+                            "Committee count must not exceed {}",
+                            shamir::MAX_COMMITTEE_SIZE
+                        ))
+                    })?;
+                Ok(vault_gate::Inbound::HandleDeclareCommittee(
+                    HandleDeclareCommittee { count },
+                ))
+            }
+            Self::ContributePassphrase(cp) => {
+                Ok(vault_gate::Inbound::HandleContributeBootstrapPassphrase(
+                    HandleContributeBootstrapPassphrase {
+                        passphrase: cp.passphrase,
+                    },
+                ))
+            }
+            Self::ContributeRecoveryPassphrase(_) => Err(Status::unimplemented(
+                "Recovery operator contributions are not available",
+            )),
+        }
+    }
+}
+
 impl TryConvert for proto_bootstrap::BootstrapEncryptedKey {
    type Output = vault_gate::Inbound;
    type Error = Status;
--- a/server/crates/arbiter-server/src/grpc/operator/vault_gate/outbound.rs
+++ b/server/crates/arbiter-server/src/grpc/operator/vault_gate/outbound.rs
@@ -1,10 +1,9 @@
 use crate::{
-    actors::vault::VaultState,
+    actors::{vault::VaultState, vault_coordinator},
    grpc::{Convert, TryConvert},
    peers::operator::vault_gate::{self as vault_gate},
 };
 use arbiter_proto::proto::{
-    shared::VaultState as ProtoVaultState,
    operator::{
        operator_response::Payload as OperatorResponsePayload,
        vault::{
@@ -17,6 +16,7 @@ use arbiter_proto::proto::{
            },
        },
    },
+    shared::VaultState as ProtoVaultState,
 };

 use tonic::Status;
@@ -34,6 +34,26 @@ const fn wrap_unseal_response(payload: UnsealResponsePayload) -> OperatorRespons
    }))
 }

+/// Ceremony errors are the operator's own doing far more often than ours, so
+/// they travel back as a specific status instead of a blanket internal error.
+fn ceremony_status(error: &vault_coordinator::Error) -> Status {
+    match error {
+        vault_coordinator::Error::AlreadyBootstrapping
+        | vault_coordinator::Error::AlreadyUnsealing
+        | vault_coordinator::Error::NotBootstrapping
+        | vault_coordinator::Error::DuplicateContribution => {
+            Status::failed_precondition(error.to_string())
+        }
+        vault_coordinator::Error::EmptyCommittee
+        | vault_coordinator::Error::UnsupportedCommittee
+        | vault_coordinator::Error::CommitteeTooLarge => {
+            Status::invalid_argument(error.to_string())
+        }
+        vault_coordinator::Error::InvalidPassphrase => Status::unauthenticated(error.to_string()),
+        _ => Status::internal("Vault ceremony failed"),
+    }
+}
+
 fn wrap_bootstrap_response(result: ProtoBootstrapResult) -> OperatorResponsePayload {
    wrap_vault_response(VaultResponsePayload::Bootstrap(proto_bootstrap::Response {
        result: result.into(),
@@ -87,7 +107,6 @@ impl TryConvert for vault_gate::Outbound {
                let proto_result = match result {
                    Ok(()) => ProtoUnsealResult::Success,
                    Err(vault_gate::Error::InvalidKey) => ProtoUnsealResult::InvalidKey,
-                    Err(vault_gate::Error::LockedOut) => ProtoUnsealResult::LockedOut,
                    Err(err) => {
                        warn!(?err, "unseal failed");
                        return Err(Status::internal("Failed to unseal vault"));
@@ -111,6 +130,56 @@ impl TryConvert for vault_gate::Outbound {
                };
                Ok(wrap_bootstrap_response(proto_result))
            }
+            Self::HandleDeclareCommittee(result) => {
+                let proto_result = match result {
+                    Ok(()) => ProtoBootstrapResult::AwaitingContributions,
+                    Err(vault_gate::Error::Ceremony(
+                        vault_coordinator::Error::AlreadyBootstrapped,
+                    )) => ProtoBootstrapResult::AlreadyBootstrapped,
+                    Err(vault_gate::Error::Ceremony(err)) => {
+                        warn!(?err, "declare committee failed");
+                        return Err(ceremony_status(&err));
+                    }
+                    Err(err) => {
+                        warn!(?err, "declare committee failed");
+                        return Err(Status::internal("Failed to declare committee"));
+                    }
+                };
+                Ok(wrap_bootstrap_response(proto_result))
+            }
+            Self::HandleContributeBootstrapPassphrase(result) => {
+                let proto_result = match result {
+                    Ok(true) => ProtoBootstrapResult::Success,
+                    Ok(false) => ProtoBootstrapResult::AwaitingContributions,
+                    Err(vault_gate::Error::Ceremony(
+                        vault_coordinator::Error::AlreadyBootstrapped,
+                    )) => ProtoBootstrapResult::AlreadyBootstrapped,
+                    Err(vault_gate::Error::Ceremony(err)) => {
+                        warn!(?err, "contribute bootstrap passphrase failed");
+                        return Err(ceremony_status(&err));
+                    }
+                    Err(err) => {
+                        warn!(?err, "contribute bootstrap passphrase failed");
+                        return Err(Status::internal(
+                            "Failed to contribute bootstrap passphrase",
+                        ));
+                    }
+                };
+                Ok(wrap_bootstrap_response(proto_result))
+            }
+            Self::HandleContributeUnsealPassphrase(result) => {
+                let proto_result = match result {
+                    Ok(true) => ProtoUnsealResult::Success,
+                    Ok(false) => ProtoUnsealResult::AwaitingContributions,
+                    Err(err) => {
+                        warn!(?err, "contribute unseal passphrase failed");
+                        return Err(Status::internal("Failed to contribute unseal passphrase"));
+                    }
+                };
+                Ok(wrap_unseal_response(UnsealResponsePayload::Result(
+                    proto_result.into(),
+                )))
+            }
        }
    }
 }
--- a/server/crates/arbiter-server/src/peers/operator/auth/state.rs
+++ b/server/crates/arbiter-server/src/peers/operator/auth/state.rs
@@ -3,8 +3,8 @@ use super::{
    Error,
 };
 use crate::{
-    actors::bootstrap::ConsumeToken,
-    db::{DatabasePool, schema::operator_identity},
+    actors::bootstrap::VerifyToken,
+    db::{DatabasePool, models::OperatorId, schema::operator_identity},
    peers::operator::auth::Outbound,
 };
 use arbiter_crypto::authn::{self, AuthChallenge, OPERATOR_CONTEXT};
@@ -37,7 +37,10 @@ smlang::statemachine!(
    }
 );

-async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<Option<i32>, Error> {
+async fn get_client_id(
+    db: &DatabasePool,
+    pubkey: &authn::PublicKey,
+) -> Result<Option<OperatorId>, Error> {
    let mut conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
        Error::internal("Database unavailable")
@@ -46,7 +49,7 @@ async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<O
    operator_identity::table
        .filter(operator_identity::public_key.eq(pubkey.to_bytes()))
        .select(operator_identity::id)
-        .first::<i32>(&mut conn)
+        .first::<OperatorId>(&mut conn)
        .await
        .optional()
        .map_err(|e| {
@@ -55,14 +58,14 @@ async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<O
        })
 }

-async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<i32, Error> {
+async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<OperatorId, Error> {
    let pubkey_bytes = pubkey.to_bytes();
    let mut conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
        Error::internal("Database unavailable")
    })?;

-    let id: i32 = diesel::insert_into(operator_identity::table)
+    let id: OperatorId = diesel::insert_into(operator_identity::table)
        .values((operator_identity::public_key.eq(pubkey_bytes),))
        .returning(operator_identity::id)
        .get_result(&mut conn)
@@ -156,7 +159,7 @@ where
                    .conn
                    .actors
                    .bootstrapper
-                    .ask(ConsumeToken { token })
+                    .ask(VerifyToken { token })
                    .await
                    .map_err(|e| {
                        error!(?e, "Failed to consume bootstrap token");
--- a/server/crates/arbiter-server/src/peers/operator/mod.rs
+++ b/server/crates/arbiter-server/src/peers/operator/mod.rs
@@ -4,7 +4,7 @@ use crate::{
        vault::{GetState, Vault},
    },
    crypto::integrity::{self, AttestationStatus, Integrable},
-    db::{DatabaseError, DatabasePool},
+    db::{DatabaseError, DatabasePool, models::OperatorId},
    peers::client::ClientProfile,
 };
 use arbiter_crypto::authn;
@@ -25,7 +25,7 @@ pub mod vault_gate;

 #[derive(Debug, Clone, Hashable)]
 pub struct Credentials {
-    pub id: i32,
+    pub id: OperatorId,
    pub pubkey: authn::PublicKey,
 }

--- a/server/crates/arbiter-server/src/peers/operator/vault_gate/mod.rs
+++ b/server/crates/arbiter-server/src/peers/operator/vault_gate/mod.rs
@@ -3,8 +3,9 @@ use crate::{
    actors::{
        GlobalActors,
        vault::{self, Bootstrap, GetState, TryUnseal, VaultState, events},
+        vault_coordinator::{self, ContributeBootstrap, ContributeUnseal, StartBootstrap},
    },
-    crypto::integrity::{self},
+    crypto::{KeyCell, integrity},
    db::DatabasePool,
 };
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
@@ -27,17 +28,27 @@ pub enum Error {
    InvalidKey,
    #[error("Vault locked: too many failed unseal attempts")]
    LockedOut,
-
    #[error("State transition failed")]
    State,
-
+    #[error("Vault ceremony failed: {0}")]
+    Ceremony(#[from] vault_coordinator::Error),
    #[error("Internal error: {0}")]
    Internal(String),
 }
+
 impl Error {
    fn internal(message: impl Into<String>) -> Self {
        Self::Internal(message.into())
    }
+
+    /// Preserve the coordinator's own error so the operator learns why a
+    /// ceremony was refused instead of reading "internal error".
+    fn ceremony<M>(error: SendError<M, vault_coordinator::Error>) -> Self {
+        match error {
+            SendError::HandlerError(inner) => Self::Ceremony(inner),
+            _ => Self::internal("VaultCoordinator unavailable"),
+        }
+    }
 }

 pub struct HandshakeResponse {
@@ -71,7 +82,6 @@ impl VaultGate {

 impl Actor for VaultGate {
    type Args = Self;
-
    type Error = ();

    async fn on_start(
@@ -102,11 +112,8 @@ impl VaultGate {
        associated_data: &[u8],
    ) -> Result<SafeCell<Vec<u8>>, ()> {
        let nonce = XNonce::from_slice(nonce);
-
        let cipher = XChaCha20Poly1305::new(secret.as_bytes().into());
-
        let mut key_buffer = SafeCell::new(ciphertext.to_vec());
-
        let decryption_result = key_buffer.write_inline(|write_handle| {
            cipher.decrypt_in_place(nonce, associated_data, write_handle)
        });
@@ -119,9 +126,13 @@ impl VaultGate {
            }
        }
    }
+
+    fn key_cell(buffer: SafeCell<Vec<u8>>) -> Result<KeyCell, Error> {
+        KeyCell::try_from(buffer).map_err(|()| Error::InvalidKey)
+    }
 }

-#[messages(messages = Inbound, replies = Outbound)]
+#[messages]
 impl VaultGate {
    #[message]
    pub fn handle_handshake(
@@ -130,14 +141,11 @@ impl VaultGate {
    ) -> Result<HandshakeResponse, Error> {
        let ephemeral_secret = EphemeralSecret::random();
        let public_key = PublicKey::from(&ephemeral_secret);
-
        let secret = ephemeral_secret.diffie_hellman(&client_pubkey);
-
        self.state = State::ReadyForExchange {
            server_key: public_key,
            secret,
        };
-
        Ok(HandshakeResponse {
            server_pubkey: public_key,
        })
@@ -153,20 +161,11 @@ impl VaultGate {
        let State::ReadyForExchange { secret, .. } = &self.state else {
            return Err(Error::State);
        };
+        let seal_key = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
+            .map_err(|()| Error::InvalidKey)
+            .and_then(Self::key_cell)?;

-        let Ok(seal_key_buffer) = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
-        else {
-            return Err(Error::InvalidKey);
-        };
-
-        match self
-            .actors
-            .vault
-            .ask(TryUnseal {
-                seal_key_raw: seal_key_buffer,
-            })
-            .await
-        {
+        match self.actors.vault.ask(TryUnseal { seal_key }).await {
            Ok(()) => {
                info!("Successfully unsealed key with client-provided key");
                Ok(())
@@ -194,17 +193,16 @@ impl VaultGate {
        let State::ReadyForExchange { secret, .. } = &self.state else {
            return Err(Error::State);
        };
-
-        let Ok(seal_key_buffer) = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
-        else {
-            return Err(Error::InvalidKey);
-        };
+        let seal_key = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
+            .map_err(|()| Error::InvalidKey)
+            .and_then(Self::key_cell)?;

        match self
            .actors
            .vault
            .ask(Bootstrap {
-                seal_key_raw: seal_key_buffer,
+                seal_key,
+                custody: None,
            })
            .await
        {
@@ -228,14 +226,53 @@ impl VaultGate {

    #[message]
    pub async fn handle_vault_state(&mut self) -> Result<VaultState, Error> {
-        let answer = self
-            .actors
+        self.actors
            .vault
            .ask(GetState {})
            .await
-            .map_err(|_| Error::internal("failed to query vault"))?;
+            .map_err(|_| Error::internal("failed to query vault"))
+    }

-        Ok(answer)
+    #[message]
+    pub async fn handle_declare_committee(&mut self, count: usize) -> Result<(), Error> {
+        self.actors
+            .vault_coordinator
+            .ask(StartBootstrap {
+                operator_id: self.auth_creds.id,
+                declared_count: count,
+            })
+            .await
+            .map_err(Error::ceremony)
+    }
+
+    #[message]
+    pub async fn handle_contribute_bootstrap_passphrase(
+        &mut self,
+        passphrase: Vec<u8>,
+    ) -> Result<bool, Error> {
+        self.actors
+            .vault_coordinator
+            .ask(ContributeBootstrap {
+                operator_id: self.auth_creds.id,
+                passphrase: SafeCell::new(passphrase),
+            })
+            .await
+            .map_err(Error::ceremony)
+    }
+
+    #[message]
+    pub async fn handle_contribute_unseal_passphrase(
+        &mut self,
+        passphrase: Vec<u8>,
+    ) -> Result<bool, Error> {
+        self.actors
+            .vault_coordinator
+            .ask(ContributeUnseal {
+                operator_id: self.auth_creds.id,
+                passphrase: SafeCell::new(passphrase),
+            })
+            .await
+            .map_err(Error::ceremony)
    }
 }

@@ -289,3 +326,75 @@ impl Message<events::Unsealed> for VaultGate {
        ctx.stop();
    }
 }
+
+pub enum Inbound {
+    HandleHandshake(HandleHandshake),
+    HandleUnsealEncryptedKey(HandleUnsealEncryptedKey),
+    HandleBootstrapEncryptedKey(HandleBootstrapEncryptedKey),
+    HandleVaultState,
+    HandleDeclareCommittee(HandleDeclareCommittee),
+    HandleContributeBootstrapPassphrase(HandleContributeBootstrapPassphrase),
+    HandleContributeUnsealPassphrase(HandleContributeUnsealPassphrase),
+}
+
+pub enum Outbound {
+    HandleHandshake(Result<HandshakeResponse, Error>),
+    HandleUnsealEncryptedKey(Result<(), Error>),
+    HandleBootstrapEncryptedKey(Result<(), Error>),
+    HandleVaultState(Result<VaultState, Error>),
+    HandleDeclareCommittee(Result<(), Error>),
+    HandleContributeBootstrapPassphrase(Result<bool, Error>),
+    HandleContributeUnsealPassphrase(Result<bool, Error>),
+}
+
+impl Message<Inbound> for VaultGate {
+    type Reply = Result<Outbound, Error>;
+
+    async fn handle(
+        &mut self,
+        msg: Inbound,
+        _ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
+    ) -> Self::Reply {
+        match msg {
+            Inbound::HandleHandshake(message) => Ok(Outbound::HandleHandshake(
+                self.handle_handshake(message.client_pubkey),
+            )),
+            Inbound::HandleUnsealEncryptedKey(message) => Ok(Outbound::HandleUnsealEncryptedKey(
+                self.handle_unseal_encrypted_key(
+                    message.nonce,
+                    message.ciphertext,
+                    message.associated_data,
+                )
+                .await,
+            )),
+            Inbound::HandleBootstrapEncryptedKey(message) => {
+                Ok(Outbound::HandleBootstrapEncryptedKey(
+                    self.handle_bootstrap_encrypted_key(
+                        message.nonce,
+                        message.ciphertext,
+                        message.associated_data,
+                    )
+                    .await,
+                ))
+            }
+            Inbound::HandleVaultState => {
+                Ok(Outbound::HandleVaultState(self.handle_vault_state().await))
+            }
+            Inbound::HandleDeclareCommittee(message) => Ok(Outbound::HandleDeclareCommittee(
+                self.handle_declare_committee(message.count).await,
+            )),
+            Inbound::HandleContributeBootstrapPassphrase(message) => {
+                Ok(Outbound::HandleContributeBootstrapPassphrase(
+                    self.handle_contribute_bootstrap_passphrase(message.passphrase)
+                        .await,
+                ))
+            }
+            Inbound::HandleContributeUnsealPassphrase(message) => {
+                Ok(Outbound::HandleContributeUnsealPassphrase(
+                    self.handle_contribute_unseal_passphrase(message.passphrase)
+                        .await,
+                ))
+            }
+        }
+    }
+}
--- a/server/crates/arbiter-server/tests/client/auth.rs
+++ b/server/crates/arbiter-server/tests/client/auth.rs
@@ -1,15 +1,12 @@
 use super::common::ChannelTransport;
-use arbiter_crypto::{
-    authn::{self, AuthChallenge, CLIENT_CONTEXT},
-    safecell::{SafeCell, SafeCellHandle as _},
-};
+use arbiter_crypto::authn::{self, AuthChallenge, CLIENT_CONTEXT};
 use arbiter_proto::{
    ClientMetadata,
    transport::{Receiver, Sender},
 };
 use arbiter_server::{
    actors::{GlobalActors, vault::Bootstrap},
-    crypto::integrity,
+    crypto::{KeyCell, integrity},
    db::{self, schema},
    peers::client::{ClientConnection, ClientCredentials, auth, connect_client},
 };
@@ -100,7 +97,8 @@ async fn spawn_test_actors(db: &db::DatabasePool) -> GlobalActors {
    actors
        .vault
        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
        })
        .await
        .unwrap();
@@ -340,7 +338,10 @@ pub async fn metadata_frozen_after_approval_ignores_reconnect_changes() {
            .first::<(String, Option<String>, Option<String>)>(&mut conn)
            .await
            .unwrap();
-        assert_eq!(metadata_count, 1, "frozen: no new metadata row on reconnect");
+        assert_eq!(
+            metadata_count, 1,
+            "frozen: no new metadata row on reconnect"
+        );
        assert_eq!(history_count, 0, "frozen: no history entry on reconnect");
        assert_eq!(
            current,
--- a/server/crates/arbiter-server/tests/common/mod.rs
+++ b/server/crates/arbiter-server/tests/common/mod.rs
@@ -2,10 +2,11 @@
    dead_code,
    reason = "Common test utilities that may not be used in every test"
 )]
-use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+
 use arbiter_proto::transport::{Bi, Error, Receiver, Sender};
 use arbiter_server::{
    actors::{GlobalActors, vault::Vault},
+    crypto::KeyCell,
    db::{self, schema},
 };

@@ -19,7 +20,7 @@ pub(crate) async fn bootstrapped_vault(db: &db::DatabasePool) -> Vault {
        .await
        .unwrap();
    actor
-        .bootstrap(SafeCell::new(b"test-seal-key".to_vec()))
+        .bootstrap(KeyCell::from([0u8; 32]), None)
        .await
        .unwrap();
    actor
--- a/server/crates/arbiter-server/tests/operator/auth.rs
+++ b/server/crates/arbiter-server/tests/operator/auth.rs
@@ -1,13 +1,10 @@
 use super::common::ChannelTransport;
-use arbiter_crypto::{
-    authn::{self, AuthChallenge, OPERATOR_CONTEXT},
-    safecell::{SafeCell, SafeCellHandle as _},
-};
+use arbiter_crypto::authn::{self, AuthChallenge, OPERATOR_CONTEXT};
 use arbiter_proto::transport::{Error as TransportError, Receiver, Sender};
 use arbiter_server::{
    actors::{GlobalActors, bootstrap::GetToken, vault::Bootstrap},
-    crypto::integrity,
-    db::{self, schema},
+    crypto::{KeyCell, integrity},
+    db::{self, models::OperatorId, schema},
    peers::operator::{self, Credentials, OperatorConnection, auth, vault_gate},
 };

@@ -154,13 +151,6 @@ impl Sender<auth::Inbound> for StartTestTransport {
 pub async fn bootstrap_token_auth() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-    actors
-        .vault
-        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
-        })
-        .await
-        .unwrap();
    let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();

    let (mut server_transport, mut test_transport) = ChannelTransport::new();
@@ -275,7 +265,8 @@ pub async fn challenge_auth() {
    actors
        .vault
        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
        })
        .await
        .unwrap();
@@ -285,10 +276,10 @@ pub async fn challenge_auth() {

    {
        let mut conn = db.get().await.unwrap();
-        let id: i32 = insert_into(schema::operator_identity::table)
+        let id: OperatorId = insert_into(schema::operator_identity::table)
            .values((schema::operator_identity::public_key.eq(pubkey_bytes.clone()),))
            .returning(schema::operator_identity::id)
-            .get_result(&mut conn)
+            .get_result::<OperatorId>(&mut conn)
            .await
            .unwrap();
        integrity::sign_entity(
@@ -361,7 +352,8 @@ pub async fn challenge_auth_rejects_integrity_tag_mismatch_when_unsealed() {
    actors
        .vault
        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
        })
        .await
        .unwrap();
@@ -434,7 +426,8 @@ pub async fn challenge_auth_rejects_invalid_signature() {
    actors
        .vault
        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
        })
        .await
        .unwrap();
@@ -444,10 +437,10 @@ pub async fn challenge_auth_rejects_invalid_signature() {

    {
        let mut conn = db.get().await.unwrap();
-        let id: i32 = insert_into(schema::operator_identity::table)
+        let id: OperatorId = insert_into(schema::operator_identity::table)
            .values((schema::operator_identity::public_key.eq(pubkey_bytes.clone()),))
            .returning(schema::operator_identity::id)
-            .get_result(&mut conn)
+            .get_result::<OperatorId>(&mut conn)
            .await
            .unwrap();
        integrity::sign_entity(
@@ -506,3 +499,92 @@ pub async fn challenge_auth_rejects_invalid_signature() {
        Err(auth::Error::InvalidChallengeSolution)
    ));
 }
+
+/// The bootstrap token authorises registering committee members *before* the
+/// vault exists. Once any bootstrap path succeeds it must stop working, or its
+/// holder could keep minting operator identities until the next restart.
+#[tokio::test]
+#[test_log::test]
+pub async fn bootstrap_token_rejected_after_bootstrap() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();
+
+    actors
+        .vault
+        .ask(Bootstrap {
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
+        })
+        .await
+        .unwrap();
+
+    // `Bootstrapped` travels through the message bus, so the token disappears
+    // a couple of actor turns after the bootstrap call returns.
+    let mut retired = false;
+    for _ in 0..100 {
+        if actors.bootstrapper.ask(GetToken).await.unwrap().is_none() {
+            retired = true;
+            break;
+        }
+        tokio::task::yield_now().await;
+    }
+    assert!(
+        retired,
+        "the bootstrap token must be retired once the vault is bootstrapped"
+    );
+
+    let (mut server_transport, mut test_transport) = ChannelTransport::new();
+    let db_for_task = db.clone();
+    let task = tokio::spawn(async move {
+        let mut props = OperatorConnection::new(db_for_task, actors);
+        auth::authenticate(&mut props, &mut server_transport).await
+    });
+
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: verifying_key(&new_key).into(),
+            bootstrap_token: Some(token.into_bytes()),
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(auth::Outbound::AuthChallenge { challenge }) => challenge,
+        other => panic!("Expected AuthChallenge, got {other:?}"),
+    };
+
+    let signature = sign_operator_challenge(&new_key, &challenge);
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth result");
+    assert!(
+        matches!(response, Err(auth::Error::InvalidBootstrapToken)),
+        "a spent bootstrap token must not authorise a new identity, got {response:?}"
+    );
+    assert!(task.await.unwrap().is_err(), "authentication must fail");
+
+    let mut conn = db.get().await.unwrap();
+    let registered: i64 = schema::operator_identity::table
+        .count()
+        .get_result(&mut conn)
+        .await
+        .unwrap();
+    assert_eq!(
+        registered, 0,
+        "no identity may be registered after the bootstrap"
+    );
+}
--- a/server/crates/arbiter-server/tests/operator/unseal.rs
+++ b/server/crates/arbiter-server/tests/operator/unseal.rs
@@ -1,13 +1,11 @@
-use arbiter_crypto::{
-    authn,
-    safecell::{SafeCell, SafeCellHandle as _},
-};
+use arbiter_crypto::authn;
 use arbiter_server::{
    actors::{
        GlobalActors,
        vault::{Bootstrap, Seal},
    },
-    db,
+    crypto::KeyCell,
+    db::{self, models::OperatorId},
    peers::operator::{
        Credentials,
        vault_gate::{
@@ -22,7 +20,7 @@ use tokio::sync::oneshot;
 use x25519_dalek::{EphemeralSecret, PublicKey};

 async fn setup_sealed_gate(
-    seal_key: &[u8],
+    seal_key: [u8; 32],
 ) -> (
    db::DatabasePool,
    kameo::actor::ActorRef<VaultGate>,
@@ -34,7 +32,8 @@ async fn setup_sealed_gate(
    actors
        .vault
        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(seal_key.to_vec()),
+            seal_key: KeyCell::from(seal_key),
+            custody: None,
        })
        .await
        .unwrap();
@@ -42,7 +41,10 @@ async fn setup_sealed_gate(

    let (promotion_tx, promotion_rx) = oneshot::channel();
    let pubkey = authn::SigningKey::generate().public_key();
-    let auth_creds = Credentials { id: 1, pubkey };
+    let auth_creds = Credentials {
+        id: OperatorId::from_raw(1),
+        pubkey,
+    };
    let gate = VaultGate::spawn(VaultGate::new(auth_creds, actors, db.clone(), promotion_tx));

    (db, gate, promotion_rx)
@@ -83,10 +85,10 @@ async fn client_dh_encrypt(
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_success() {
-    let seal_key = b"test-seal-key";
+    let seal_key = [7u8; 32];
    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;

-    let encrypted_key = client_dh_encrypt(&gate, seal_key).await;
+    let encrypted_key = client_dh_encrypt(&gate, &seal_key).await;

    let response = gate.ask(encrypted_key).await;
    assert!(matches!(response, Ok(())));
@@ -95,10 +97,10 @@ pub async fn unseal_success() {
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_wrong_seal_key() {
-    let seal_key = b"test-seal-key";
+    let seal_key = [7u8; 32];
    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;

-    let encrypted_key = client_dh_encrypt(&gate, b"wrong-key").await;
+    let encrypted_key = client_dh_encrypt(&gate, &[8u8; 32]).await;

    let response = gate.ask(encrypted_key).await;
    assert!(matches!(
@@ -112,7 +114,7 @@ pub async fn unseal_wrong_seal_key() {
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_corrupted_ciphertext() {
-    let seal_key = b"test-seal-key";
+    let seal_key = [7u8; 32];
    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;

    let client_secret = EphemeralSecret::random();
@@ -143,11 +145,11 @@ pub async fn unseal_corrupted_ciphertext() {
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_retry_after_invalid_key() {
-    let seal_key = b"real-seal-key";
+    let seal_key = [9u8; 32];
    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;

    {
-        let encrypted_key = client_dh_encrypt(&gate, b"wrong-key").await;
+        let encrypted_key = client_dh_encrypt(&gate, &[8u8; 32]).await;

        let response = gate.ask(encrypted_key).await;
        assert!(matches!(
@@ -159,7 +161,7 @@ pub async fn unseal_retry_after_invalid_key() {
    }

    {
-        let encrypted_key = client_dh_encrypt(&gate, seal_key).await;
+        let encrypted_key = client_dh_encrypt(&gate, &seal_key).await;

        let response = gate.ask(encrypted_key).await;
        assert!(matches!(response, Ok(())));
--- a/server/crates/arbiter-server/tests/vault.rs
+++ b/server/crates/arbiter-server/tests/vault.rs
@@ -2,6 +2,8 @@ mod common;

 #[path = "vault/concurrency.rs"]
 mod concurrency;
+#[path = "vault/custody.rs"]
+mod custody;
 #[path = "vault/lifecycle.rs"]
 mod lifecycle;
 #[path = "vault/storage.rs"]
--- a/server/crates/arbiter-server/tests/vault/concurrency.rs
+++ b/server/crates/arbiter-server/tests/vault/concurrency.rs
@@ -5,6 +5,7 @@ use arbiter_server::{
        GlobalActors,
        vault::{CreateNew, Error, Vault},
    },
+    crypto::KeyCell,
    db::{self, models, schema},
 };

@@ -169,7 +170,7 @@ async fn decrypt_roundtrip_after_high_concurrency() {
        .await
        .unwrap();
    decryptor
-        .try_unseal(SafeCell::new(b"test-seal-key".to_vec()))
+        .try_unseal(KeyCell::from([0u8; 32]))
        .await
        .unwrap();

--- a/server/crates/arbiter-server/tests/vault/custody.rs
+++ b/server/crates/arbiter-server/tests/vault/custody.rs
@@ -0,0 +1,317 @@
+//! End-to-end coverage for the Shamir custody ceremonies.
+
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use arbiter_server::{
+    actors::{
+        GlobalActors,
+        vault::{Bootstrap, GetState, Seal, VaultState},
+        vault_coordinator::{ContributeBootstrap, ContributeUnseal, StartBootstrap},
+    },
+    crypto::{KeyCell, shamir},
+    db::{self, models::OperatorId, schema},
+};
+
+use diesel::{ExpressionMethods as _, QueryDsl};
+use diesel_async::RunQueryDsl;
+
+/// Register `count` operator identities so committee members satisfy the
+/// foreign key from `operator` to `operator_identity`.
+async fn register_operators(db: &db::DatabasePool, count: usize) -> Vec<OperatorId> {
+    let mut conn = db.get().await.unwrap();
+    let mut ids = Vec::with_capacity(count);
+    for index in 0..count {
+        let pubkey = vec![u8::try_from(index).unwrap(); 32];
+        let id: OperatorId = diesel::insert_into(schema::operator_identity::table)
+            .values((schema::operator_identity::public_key.eq(pubkey),))
+            .returning(schema::operator_identity::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap();
+        ids.push(id);
+    }
+    ids
+}
+
+async fn stored_share_count(db: &db::DatabasePool) -> i64 {
+    let mut conn = db.get().await.unwrap();
+    schema::operator::table
+        .count()
+        .get_result(&mut conn)
+        .await
+        .unwrap()
+}
+
+async fn stored_threshold(db: &db::DatabasePool) -> Option<i32> {
+    let mut conn = db.get().await.unwrap();
+    schema::arbiter_settings::table
+        .select(schema::arbiter_settings::shamir_threshold)
+        .first(&mut conn)
+        .await
+        .unwrap()
+}
+
+fn passphrase(seed: u8) -> SafeCell<Vec<u8>> {
+    SafeCell::new(vec![seed; 16])
+}
+
+/// The happy path: three operators bootstrap, and any two of them reopen the
+/// vault after it is sealed.
+#[tokio::test]
+#[test_log::test]
+async fn committee_of_three_unseals_with_two_passphrases() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 3).await;
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 3,
+        })
+        .await
+        .unwrap();
+
+    for (index, operator_id) in operators.iter().enumerate() {
+        let finished = actors
+            .vault_coordinator
+            .ask(ContributeBootstrap {
+                operator_id: *operator_id,
+                passphrase: passphrase(u8::try_from(index).unwrap()),
+            })
+            .await
+            .unwrap();
+        assert_eq!(
+            finished,
+            index == 2,
+            "the ceremony finishes only on the last contribution"
+        );
+    }
+
+    assert_eq!(
+        actors.vault.ask(GetState {}).await.unwrap(),
+        VaultState::Unsealed
+    );
+    assert_eq!(stored_share_count(&db).await, 3);
+    assert_eq!(stored_threshold(&db).await, Some(2));
+
+    actors.vault.ask(Seal {}).await.unwrap();
+
+    let first = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[0],
+            passphrase: passphrase(0),
+        })
+        .await
+        .unwrap();
+    assert!(!first, "one of two shares must not unseal");
+
+    let second = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[2],
+            passphrase: passphrase(2),
+        })
+        .await
+        .unwrap();
+    assert!(second, "the threshold contribution should unseal the vault");
+    assert_eq!(
+        actors.vault.ask(GetState {}).await.unwrap(),
+        VaultState::Unsealed
+    );
+}
+
+/// Shares that describe a seal key the vault never adopted would make the vault
+/// permanently un-unsealable, so a refused bootstrap must leave the table empty.
+#[tokio::test]
+#[test_log::test]
+async fn refused_bootstrap_stores_no_shares() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 1).await;
+
+    // Another path bootstraps the vault first; the ceremony now has nowhere to go.
+    actors
+        .vault
+        .ask(Bootstrap {
+            seal_key: KeyCell::from([4u8; 32]),
+            custody: None,
+        })
+        .await
+        .unwrap();
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 1,
+        })
+        .await
+        .unwrap();
+
+    let error = actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(1),
+        })
+        .await
+        .expect_err("bootstrapping an already bootstrapped vault must fail");
+    assert!(
+        format!("{error:?}").contains("AlreadyBootstrapped"),
+        "expected AlreadyBootstrapped, got {error:?}"
+    );
+
+    assert_eq!(
+        stored_share_count(&db).await,
+        0,
+        "a refused bootstrap must not leave shares behind"
+    );
+    assert_eq!(
+        stored_threshold(&db).await,
+        None,
+        "a refused bootstrap must not leave a threshold behind"
+    );
+}
+
+#[tokio::test]
+#[test_log::test]
+async fn oversized_and_degenerate_committees_are_rejected() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 1).await;
+
+    for (count, expected) in [
+        (0_usize, "EmptyCommittee"),
+        (2, "UnsupportedCommittee"),
+        (shamir::MAX_COMMITTEE_SIZE + 1, "CommitteeTooLarge"),
+        (usize::MAX, "CommitteeTooLarge"),
+    ] {
+        let error = actors
+            .vault_coordinator
+            .ask(StartBootstrap {
+                operator_id: operators[0],
+                declared_count: count,
+            })
+            .await
+            .expect_err("committee size must be rejected");
+        assert!(
+            format!("{error:?}").contains(expected),
+            "expected {expected} for count {count}, got {error:?}"
+        );
+    }
+}
+
+/// A committee whose members never all show up would otherwise wedge the
+/// coordinator until restart. Only the operator that declared it may reset it.
+#[tokio::test]
+#[test_log::test]
+async fn only_the_declarer_may_restart_a_stalled_committee() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 3).await;
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 3,
+        })
+        .await
+        .unwrap();
+    actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(0),
+        })
+        .await
+        .unwrap();
+
+    let error = actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[1],
+            declared_count: 3,
+        })
+        .await
+        .expect_err("a bystander must not reset someone else's ceremony");
+    assert!(
+        format!("{error:?}").contains("AlreadyBootstrapping"),
+        "expected AlreadyBootstrapping, got {error:?}"
+    );
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 1,
+        })
+        .await
+        .expect("the declarer may restart the ceremony");
+
+    let finished = actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(0),
+        })
+        .await
+        .unwrap();
+    assert!(
+        finished,
+        "the restarted one-operator ceremony should complete"
+    );
+    assert_eq!(stored_share_count(&db).await, 1);
+}
+
+/// A wrong passphrase must not unseal, and the operator must be able to retry.
+#[tokio::test]
+#[test_log::test]
+async fn wrong_passphrase_is_rejected_and_retryable() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 1).await;
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 1,
+        })
+        .await
+        .unwrap();
+    actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(7),
+        })
+        .await
+        .unwrap();
+    actors.vault.ask(Seal {}).await.unwrap();
+
+    let error = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[0],
+            passphrase: passphrase(8),
+        })
+        .await
+        .expect_err("a wrong passphrase must not unseal");
+    assert!(
+        format!("{error:?}").contains("InvalidPassphrase"),
+        "expected InvalidPassphrase, got {error:?}"
+    );
+
+    let unsealed = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[0],
+            passphrase: passphrase(7),
+        })
+        .await
+        .expect("the operator may retry with the correct passphrase");
+    assert!(unsealed, "the retry should unseal the vault");
+}
--- a/server/crates/arbiter-server/tests/vault/lifecycle.rs
+++ b/server/crates/arbiter-server/tests/vault/lifecycle.rs
@@ -5,7 +5,10 @@ use arbiter_server::{
        GlobalActors,
        vault::{Error, Vault},
    },
-    crypto::encryption::v1::{Nonce, ROOT_KEY_TAG},
+    crypto::{
+        KeyCell,
+        encryption::v1::{Nonce, ROOT_KEY_TAG},
+    },
    db::{self, models, schema},
 };

@@ -22,8 +25,8 @@ async fn bootstrap() {
        .await
        .unwrap();

-    let seal_key = SafeCell::new(b"test-seal-key".to_vec());
-    actor.bootstrap(seal_key).await.unwrap();
+    let seal_key = KeyCell::from([0u8; 32]);
+    actor.bootstrap(seal_key, None).await.unwrap();

    let mut conn = db.get().await.unwrap();
    let row: models::RootKeyHistory = schema::root_key_history::table
@@ -45,8 +48,8 @@ async fn bootstrap_rejects_double() {
    let db = db::create_test_pool().await;
    let mut actor = common::bootstrapped_vault(&db).await;

-    let seal_key2 = SafeCell::new(b"test-seal-key".to_vec());
-    let err = actor.bootstrap(seal_key2).await.unwrap_err();
+    let seal_key2 = KeyCell::from([0u8; 32]);
+    let err = actor.bootstrap(seal_key2, None).await.unwrap_err();
    assert!(matches!(err, Error::AlreadyBootstrapped));
 }

@@ -107,7 +110,7 @@ async fn unseal_correct_password() {
    let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
        .await
        .unwrap();
-    let seal_key = SafeCell::new(b"test-seal-key".to_vec());
+    let seal_key = KeyCell::from([0u8; 32]);
    actor.try_unseal(seal_key).await.unwrap();

    let mut decrypted = actor.decrypt(aead_id, TEST_AAD.to_vec()).await.unwrap();
@@ -131,11 +134,11 @@ async fn unseal_wrong_then_correct_password() {
        .await
        .unwrap();

-    let bad_key = SafeCell::new(b"wrong-password".to_vec());
+    let bad_key = KeyCell::from([1u8; 32]);
    let err = actor.try_unseal(bad_key).await.unwrap_err();
    assert!(matches!(err, Error::InvalidKey));

-    let good_key = SafeCell::new(b"test-seal-key".to_vec());
+    let good_key = KeyCell::from([0u8; 32]);
    actor.try_unseal(good_key).await.unwrap();

    let mut decrypted = actor.decrypt(aead_id, TEST_AAD.to_vec()).await.unwrap();
Author	SHA1	Message	Date
CleverWild	62fb83469f	refactor(custody): drop the single-implementation CustodyStore trait	2026-09-11 15:45:21 +02:00
CleverWild	d49c39130a	fix(vault): apply Shamir custody review feedback	2026-09-11 15:02:59 +02:00
CleverWild	c722712166	feat(vault)!: add multi-operator Shamir custody	2026-09-11 10:48:01 +02:00