feat(vault)!: add multi-operator Shamir custody

server/Cargo.lock

@@ -504,7 +504,7 @@ dependencies = [
  "async-trait",
  "auto_impl",
  "either",
- "elliptic-curve 0.13.8",
+ "elliptic-curve",
  "k256",
  "thiserror",
 ]
@@ -772,6 +772,7 @@ dependencies = [
  "prost-types",
  "rand 0.10.1",
  "rand_core 0.10.1",
+ "rand_core 0.6.4",
  "rcgen",
  "restructed",
  "rstest",
@@ -822,7 +823,7 @@ dependencies = [
  "ark-serialize 0.3.0",
  "ark-std 0.3.0",
  "derivative",
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-traits",
  "paste",
  "rustc_version 0.3.3",
@@ -842,7 +843,7 @@ dependencies = [
  "derivative",
  "digest 0.10.7",
  "itertools 0.10.5",
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-traits",
  "paste",
  "rustc_version 0.4.1",
@@ -863,7 +864,7 @@ dependencies = [
  "digest 0.10.7",
  "educe",
  "itertools 0.13.0",
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-traits",
  "paste",
  "zeroize",
@@ -905,7 +906,7 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "db2fd794a08ccb318058009eefdf15bcaaaaf6f8161eb3345f907222bac38b20"
 dependencies = [
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-traits",
  "quote",
  "syn 1.0.109",
@@ -917,7 +918,7 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7abe79b0e4288889c4574159ab790824d0033b9fdcb2a112a3182fac2e514565"
 dependencies = [
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-traits",
  "proc-macro2",
  "quote",
@@ -930,7 +931,7 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09be120733ee33f7693ceaa202ca41accd5653b779563608f1234f78ae07c4b3"
 dependencies = [
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-traits",
  "proc-macro2",
  "quote",
@@ -955,7 +956,7 @@ checksum = "adb7b85a02b83d2f22f89bd5cac66c9c89474240cb6207cb1efc16d098e822a5"
 dependencies = [
  "ark-std 0.4.0",
  "digest 0.10.7",
- "num-bigint 0.4.6",
+ "num-bigint",
 ]
 
 [[package]]
@@ -967,7 +968,7 @@ dependencies = [
  "ark-std 0.5.0",
  "arrayvec",
  "digest 0.10.7",
- "num-bigint 0.4.6",
+ "num-bigint",
 ]
 
 [[package]]
@@ -1197,12 +1198,6 @@ 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"
@@ -1560,12 +1555,6 @@ 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"
@@ -1628,22 +1617,20 @@ checksum = "0dc92fb57ca44df6db8059111ab3af99a63d5d0f8375d9972e319a379c6bab76"
 dependencies = [
  "generic-array 0.14.7",
  "rand_core 0.6.4",
+ "serdect 0.2.0",
  "subtle",
  "zeroize",
 ]
 
 [[package]]
 name = "crypto-bigint"
-version = "0.7.5"
+version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a52aa3fcda4e6302a9f48734f234d35d4721b96f8fe07d073f07ce9df4f0271"
+checksum = "96272c2ff28b807e09250b180ad1fb7889a3258f7455759b5c3c58b719467130"
 dependencies = [
- "cpubits",
- "ctutils",
- "hybrid-array",
  "num-traits",
- "rand_core 0.10.1",
+ "rand_core 0.6.4",
- "serdect 0.4.3",
+ "serdect 0.3.0",
  "subtle",
  "zeroize",
 ]
@@ -1676,7 +1663,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7d5515a3834141de9eafb9717ad39eea8247b5674e6066c404e8c4b365d2a29e"
 dependencies = [
  "cmov",
- "subtle",
 ]
 
 [[package]]
@@ -1839,7 +1825,7 @@ dependencies = [
  "asn1-rs",
  "displaydoc",
  "nom",
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-traits",
  "rusticata-macros",
 ]
@@ -2036,7 +2022,7 @@ checksum = "ee27f32b5c5292967d2d4a9d7f1e0b0aed2c15daded5a60300e4abb9d8020bca"
 dependencies = [
  "der 0.7.10",
  "digest 0.10.7",
- "elliptic-curve 0.13.8",
+ "elliptic-curve",
  "rfc6979",
  "serdect 0.2.0",
  "signature 2.2.0",
@@ -2070,50 +2056,34 @@ version = "0.13.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b5e6043086bf7973472e0c7dff2142ea0b680d30e18d9cc40f267efbf222bd47"
 dependencies = [
- "base16ct 0.2.0",
+ "base16ct",
  "crypto-bigint 0.5.5",
  "digest 0.10.7",
- "ff 0.13.1",
+ "ff",
  "generic-array 0.14.7",
- "group 0.13.0",
+ "group",
+ "hkdf",
  "pkcs8 0.10.2",
  "rand_core 0.6.4",
- "sec1 0.7.3",
+ "sec1",
  "serdect 0.2.0",
  "subtle",
- "zeroize",
+ "tap",
-]
-
-[[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"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a0d5e534f103b079a71ef1d66c6e62c89413f1b62709ca11f744429b4afe5b4"
+checksum = "1de2b6fae800f08032a6ea32995b52925b1d451bff9d445c8ab2932323277faf"
 dependencies = [
- "elliptic-curve 0.14.1",
+ "elliptic-curve",
  "heapless",
+ "hex",
+ "multiexp",
  "serde",
- "serdect 0.4.3",
+ "zeroize",
 ]
 
 [[package]]
@@ -2186,20 +2156,11 @@ version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c0b50bfb653653f9ca9095b427bed08ab8d75a137839d9ad64eb11810d5b6393"
 dependencies = [
+ "bitvec",
  "rand_core 0.6.4",
  "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"
@@ -2466,22 +2427,11 @@ version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f0f9ef7462f7c099f518d754361858f86d8a07af53ba9af0fe635bbccb151a63"
 dependencies = [
- "ff 0.13.1",
+ "ff",
  "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"
@@ -2552,9 +2502,9 @@ checksum = "4f467dd6dccf739c208452f8014c75c18bb8301b050ad1cfb27153803edb0f51"
 
 [[package]]
 name = "heapless"
-version = "0.9.3"
+version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "25ba4bd83f9415b58b4ed8dc5714c76e626a105be4646c02630ad730ad3b5aa4"
+checksum = "0bfb9eb618601c89945a70e254898da93b13be0388091d42117462b265bb3fad"
 dependencies = [
  "hash32",
  "stable_deref_trait",
@@ -2587,6 +2537,15 @@ dependencies = [
  "arrayvec",
 ]
 
+[[package]]
+name = "hkdf"
+version = "0.12.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b5f8eb2ad728638ea2c7d47a21db23b7b58a72ed6a38256b8a1849f15fbbdf7"
+dependencies = [
+ "hmac 0.12.1",
+]
+
 [[package]]
 name = "hmac"
 version = "0.12.1"
@@ -2652,13 +2611,12 @@ checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"
 
 [[package]]
 name = "hybrid-array"
-version = "0.4.15"
+version = "0.4.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "27f864f10dfb56725ce5ce5472bc52252c8f93a4ab86327122cebf62c5f59a17"
+checksum = "08d46837a0ed51fe95bd3b05de33cd64a1ee88fc797477ca48446872504507c5"
 dependencies = [
  "ctutils",
  "serde",
- "subtle",
  "typenum",
  "zeroize",
 ]
@@ -3061,7 +3019,7 @@ checksum = "f6e3919bbaa2945715f0bb6d3934a173d1e9a59ac23767fbaaef277265a7411b"
 dependencies = [
  "cfg-if",
  "ecdsa",
- "elliptic-curve 0.13.8",
+ "elliptic-curve",
  "once_cell",
  "serdect 0.2.0",
  "sha2 0.10.9",
@@ -3405,6 +3363,20 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "multiexp"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ec2ce93a6f06ac6cae04c1da3f2a6a24fcfc1f0eb0b4e0f3d302f0df45326cb"
+dependencies = [
+ "ff",
+ "group",
+ "rand_core 0.6.4",
+ "rustversion",
+ "std-shims",
+ "zeroize",
+]
+
 [[package]]
 name = "multimap"
 version = "0.10.1"
@@ -3436,6 +3408,20 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "num"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "35bd024e8b2ff75562e5f34e7f4905839deb4b22955ef5e73d2fea1b9813cb23"
+dependencies = [
+ "num-bigint",
+ "num-complex",
+ "num-integer",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.4.6"
@@ -3444,16 +3430,18 @@ checksum = "a5e44f723f1133c9deac646763579fdb3ac745e418f2a7af9cd0c431da1f20b9"
 dependencies = [
  "num-integer",
  "num-traits",
+ "rand 0.8.6",
+ "serde",
 ]
 
 [[package]]
-name = "num-bigint"
+name = "num-complex"
-version = "0.5.1"
+version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "93e7820bc0a80a0238e650327316f929ba18d5be054b647490a3a6a339f3e7c0"
+checksum = "73f88a1307638156682bada9d7604135552957b7818057dcef22705b4d509495"
 dependencies = [
- "num-integer",
  "num-traits",
+ "rand 0.8.6",
  "serde",
 ]
 
@@ -3472,6 +3460,28 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "num-iter"
+version = "0.1.46"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c92800bd69a1eac91786bcfe9da64a897eb72911b8dc3095decbd07429e8048b"
+dependencies = [
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f83d14da390562dca69fc84082e73e548e1ad308d24accdedd2720017cb37824"
+dependencies = [
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+ "serde",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
@@ -4351,7 +4361,7 @@ dependencies = [
  "bytes",
  "fastrlp 0.3.1",
  "fastrlp 0.4.0",
- "num-bigint 0.4.6",
+ "num-bigint",
  "num-integer",
  "num-traits",
  "parity-scale-codec",
@@ -4578,7 +4588,7 @@ version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d3e97a565f76233a6003f9f5c54be1d9c5bdfa3eccfb189469f11ec4901c47dc"
 dependencies = [
- "base16ct 0.2.0",
+ "base16ct",
  "der 0.7.10",
  "generic-array 0.14.7",
  "pkcs8 0.10.2",
@@ -4587,21 +4597,6 @@ dependencies = [
  "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",
-]
-
 [[package]]
 name = "secp256k1"
 version = "0.30.0"
@@ -4759,17 +4754,17 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a84f14a19e9a014bb9f4512488d9829a68e04ecabffb0f9904cd1ace94598177"
 dependencies = [
- "base16ct 0.2.0",
+ "base16ct",
  "serde",
 ]
 
 [[package]]
 name = "serdect"
-version = "0.4.3"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "66cf8fedced2fcf12406bcb34223dffb92eaf34908ede12fed414c82b7f00b3e"
+checksum = "f42f67da2385b51a5f9652db9c93d78aeaf7610bf5ec366080b6de810604af53"
 dependencies = [
- "base16ct 1.0.0",
+ "base16ct",
  "serde",
 ]
 
@@ -4815,17 +4810,6 @@ 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"
@@ -4836,17 +4820,6 @@ 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"
@@ -4960,6 +4933,12 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "spin"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "023a211cb3138dbc438680b32560ad89f699977624c9f8dbb95a47d5b4c07dd3"
+
 [[package]]
 name = "spki"
 version = "0.7.3"
@@ -4980,12 +4959,6 @@ 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"
@@ -5010,6 +4983,17 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 
+[[package]]
+name = "std-shims"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "227c4f8561598188d0df96dbe749824576174bba278b5b6bb2eacff1066067d0"
+dependencies = [
+ "hashbrown 0.16.1",
+ "rustversion",
+ "spin",
+]
+
 [[package]]
 name = "string_morph"
 version = "0.1.0"
@@ -5766,23 +5750,21 @@ checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
 
 [[package]]
 name = "vsss-rs"
-version = "6.0.1"
+version = "5.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d6bfc736cfd88115aedb95ba84bc2d428fe351e92a56f69fce090af301402d91"
+checksum = "6ec751bdcc8bda099e269b24cc6b4ad14f9ce8b0490c1599174070e792ecd70c"
 dependencies = [
- "crypto-bigint 0.7.5",
+ "crypto-bigint 0.5.5",
- "elliptic-curve 0.14.1",
+ "crypto-bigint 0.6.1",
+ "elliptic-curve",
  "elliptic-curve-tools",
- "ff 0.14.0",
  "generic-array 1.4.2",
  "hex",
  "hybrid-array",
- "num-bigint 0.5.1",
+ "num",
- "num-traits",
+ "rand_core 0.6.4",
- "rand_core 0.10.1",
  "serde",
- "sha3 0.12.0",
+ "sha3 0.10.9",
- "shake",
  "subtle",
  "zeroize",
 ]

server/Cargo.toml

@@ -78,7 +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
+unused_async_trait_impl = "allow" # to pedantic
 
 # restriction lints
 alloc_instead_of_core = "warn"

server/crates/arbiter-server/Cargo.toml

@@ -51,7 +51,8 @@ subtle = "2.6.1"
 x25519-dalek.workspace = true
 k256.workspace = true
 kameo_actors.workspace = true
-vsss-rs = "6.0.1"
+vsss-rs = "5.4.0"
+rand_core_06 = { package = "rand_core", version = "0.6" }
 
 [dev-dependencies]
 proptest = "1.11.0"

server/crates/arbiter-server/src/actors/bootstrap.rs

@@ -76,9 +76,6 @@ pub enum Error {
 /// 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>,
@@ -119,13 +116,41 @@ impl Bootstrapper {
             });
         }
 
+        let registered = diesel::select(diesel::dsl::exists(
+            schema::operator_identity::table.select(schema::operator_identity::id),
+        ))
+        .get_result::<bool>(&mut conn)
+        .await?;
+
+        let token = if registered {
+            match tokio::fs::read_to_string(&path).await {
+                Ok(existing)
+                    if existing.len() == TOKEN_LENGTH
+                        && existing.chars().all(|c| c.is_ascii_alphanumeric()) =>
+                {
+                    let mut cell = SafeCell::new([0u8; TOKEN_LENGTH]);
+                    cell.write().copy_from_slice(existing.as_bytes());
+                    cell
+                }
+                Ok(_) | Err(_) => generate_token(&path).await?,
+            }
+        } else {
+            generate_token(&path).await?
+        };
+
         Ok(Self {
-            token: Some(generate_token(&path).await?),
+            token: Some(token),
             token_path: Some(path),
             events,
         })
     }
 
+    fn is_correct_token(&mut self, token: &[u8]) -> bool {
+        self.token.as_mut().is_some_and(|expected| {
+            expected.read_inline(|bytes| bool::from(bytes.as_ref().ct_eq(token)))
+        })
+    }
+
     async fn forget(&mut self) {
         self.token = None;
         if let Some(path) = self.token_path.take() {
@@ -150,9 +175,7 @@ impl Message<events::Bootstrapped> for Bootstrapper {
 impl Bootstrapper {
     #[message]
     pub fn verify_token(&mut self, token: Vec<u8>) -> bool {
-        self.token.as_mut().is_some_and(|expected| {
+        self.is_correct_token(&token)
-            expected.read_inline(|bytes| bool::from(bytes.as_ref().ct_eq(token.as_slice())))
-        })
     }
 
     #[message]

server/crates/arbiter-server/src/actors/vault_coordinator/mod.rs

@@ -9,8 +9,7 @@ use std::sync::Arc;
 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_06::{OsRng, RngCore as _};
-use rand_core::{Rng as _, UnwrapErr};
 
 use crate::{
     actors::vault::{self, Bootstrap, TryUnseal, Vault},
@@ -144,7 +143,7 @@ fn encrypt_share(
     share: &[u8],
 ) -> Result<EncryptedShare, Error> {
     let mut salt = [0u8; RECOMMENDED_SALT_LEN];
-    UnwrapErr(SysRng).fill_bytes(&mut salt);
+    OsRng.fill_bytes(&mut salt);
 
     let nonce = Nonce::default();
     let ciphertext = derive_key(passphrase, &salt)
@@ -189,17 +188,15 @@ async fn finalize_bootstrap(
     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))
+    let mut shares = shamir::split_key(threshold, total, &mut seal_key, OsRng)
         .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()) {
+    for (index, (operator_id, passphrase)) in contributions.0.iter_mut().enumerate() {
-        let share = share.read_inline(|share| encrypt_share(passphrase, share))?;
+        let share = shares
-        encrypted.push((*operator_id, share));
+            .read_inline(|shares| shares.get(index).cloned())
+            .ok_or_else(|| Error::Shamir("missing share for operator".to_owned()))?;
+        encrypted.push((*operator_id, encrypt_share(passphrase, &share)?));
     }
 
     vault
@@ -229,9 +226,12 @@ async fn finalize_unseal(
             .await?
     };
 
-    let mut plaintext = Vec::with_capacity(stored.len());
+    let mut plaintext = SafeCell::new(Vec::with_capacity(stored.len()));
     for ((_, passphrase), share) in contributions.0.iter_mut().zip(stored) {
-        plaintext.push(decrypt_share(passphrase, share)?);
+        let mut decrypted = decrypt_share(passphrase, share)?;
+        decrypted.read_inline(|share| {
+            plaintext.write_inline(|shares| shares.push(share.clone()));
+        });
     }
 
     let seal_key = shamir::combine_shares(threshold, &mut plaintext)

server/crates/arbiter-server/src/crypto/shamir.rs

@@ -1,5 +1,4 @@
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
-use rand_core::CryptoRng;
 use vsss_rs::Gf256;
 
 use crate::crypto::KeyCell;
@@ -16,13 +15,10 @@ pub enum ShamirError {
     Combine(String),
 }
 
-/// Return the required threshold for a Shamir share pool of `committee_size`.
+/// Return the required majority threshold for an ordinary operator committee.
 ///
-/// A pool of two is rejected: a majority of two is two, which gives each holder
+/// Committees of two are rejected: a majority of two is two, which gives each
-/// a veto over every unseal without giving either one recovery. That rejects no
+/// member a veto over every unseal without giving either one recovery.
-/// 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"
@@ -42,8 +38,8 @@ pub fn split_key(
     threshold: usize,
     total: usize,
     key: &mut KeyCell,
-    rng: impl CryptoRng,
+    mut rng: impl rand_core_06::RngCore + rand_core_06::CryptoRng,
-) -> Result<Vec<SafeCell<Vec<u8>>>, ShamirError> {
+) -> Result<SafeCell<Vec<Vec<u8>>>, ShamirError> {
     if total == 0 || threshold == 0 || threshold > total || total == 2 || total > MAX_COMMITTEE_SIZE
     {
         return Err(ShamirError::Split(
@@ -51,23 +47,20 @@ pub fn split_key(
         ));
     }
 
-    // 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)
+        if threshold == 1 {
-            .map(|shares| shares.into_iter().map(SafeCell::new).collect())
+            return Ok(SafeCell::new(
+                std::iter::repeat_n(key.to_vec(), total).collect(),
+            ));
+        }
+
+        Gf256::split_array(threshold, total, key, &mut rng)
+            .map(SafeCell::new)
             .map_err(|error| ShamirError::Split(format!("{error:?}")))
     })
 }
@@ -80,43 +73,30 @@ pub fn split_key(
 /// sized.
 pub fn combine_shares(
     threshold: usize,
-    shares: &mut [SafeCell<Vec<u8>>],
+    shares: &mut SafeCell<Vec<Vec<u8>>>,
 ) -> Result<KeyCell, ShamirError> {
     if threshold == 0 {
         return Err(ShamirError::Combine("threshold is zero".to_owned()));
     }
-    if shares.len() < threshold {
+    if shares.read().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.
+    let combined = shares.read_inline(|shares| {
-    if threshold == 1 {
+        if threshold == 1 {
-        let share = shares
+            let share = shares
-            .first_mut()
+                .first()
-            .ok_or_else(|| ShamirError::Combine("no shares supplied".to_owned()))?;
+                .ok_or_else(|| ShamirError::Combine("no shares supplied".to_owned()))?;
-        return reconstructed_key(share.read_inline(|share| SafeCell::new(share.clone())));
+            return Ok(SafeCell::new(share.clone()));
-    }
+        }
-
+        Gf256::combine_array(shares)
-    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)
+    KeyCell::try_from(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()))
 }
 
@@ -125,9 +105,6 @@ 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| {
@@ -137,36 +114,35 @@ mod tests {
         })
     }
 
-    fn select(shares: &mut [SafeCell<Vec<u8>>], indexes: &[usize]) -> Vec<SafeCell<Vec<u8>>> {
+    fn select(shares: &mut SafeCell<Vec<Vec<u8>>>, indexes: &[usize]) -> SafeCell<Vec<Vec<u8>>> {
-        indexes
+        shares.read_inline(|shares| {
-            .iter()
+            SafeCell::new(
-            .filter_map(|index| {
+                indexes
-                shares
+                    .iter()
-                    .get_mut(*index)
+                    .filter_map(|index| shares.get(*index).cloned())
-                    .map(|share| share.read_inline(|share| SafeCell::new(share.clone())))
+                    .collect(),
-            })
+            )
-            .collect()
+        })
     }
 
-    #[rstest]
+    #[test]
-    #[case(&[0, 1])]
+    fn threshold_shares_reconstruct_fixed_key() {
-    #[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 rng = rand_core_06::OsRng;
         let mut shares = split_key(2, 3, &mut key, rng).expect("split should succeed");
-        let mut selected = select(&mut shares, indexes);
+        for indexes in [[0_usize, 1_usize], [0, 2], [1, 2]] {
-        let combined = combine_shares(2, &mut selected).expect("combine should succeed");
+            let mut selected = select(&mut shares, &indexes);
-        assert_eq!(key_bytes(combined), expected);
+            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 rng = rand_core_06::OsRng;
         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);
@@ -175,7 +151,7 @@ mod tests {
     #[test]
     fn fewer_shares_than_threshold_is_rejected() {
         let mut key = KeyCell::from([3_u8; 32]);
-        let rng = UnwrapErr(SysRng);
+        let rng = rand_core_06::OsRng;
         let mut shares = split_key(3, 5, &mut key, rng).expect("split should succeed");
         let mut selected = select(&mut shares, &[0, 1]);
         assert!(
@@ -184,25 +160,24 @@ mod tests {
         );
     }
 
-    #[rstest]
+    #[test]
-    #[case(0, None)]
+    fn empty_committee_has_no_threshold() {
-    #[case(1, Some(1))]
+        assert_eq!(shamir_threshold(0), None);
-    #[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() {
+    fn committee_threshold_is_majority_for_three_or_more() {
+        assert_eq!(shamir_threshold(1), Some(1));
+        assert_eq!(shamir_threshold(3), Some(2));
+        assert_eq!(shamir_threshold(4), Some(3));
+    }
+
+    #[test]
+    fn oversized_committee_has_no_threshold() {
+        assert_eq!(shamir_threshold(MAX_COMMITTEE_SIZE), Some(128));
+        assert_eq!(shamir_threshold(MAX_COMMITTEE_SIZE + 1), None);
         let mut key = KeyCell::from([1_u8; 32]);
-        let rng = UnwrapErr(SysRng);
+        let rng = rand_core_06::OsRng;
         assert!(
             split_key(129, MAX_COMMITTEE_SIZE + 1, &mut key, rng).is_err(),
             "committees above the GF(256) share limit must be rejected"
@@ -211,8 +186,9 @@ mod tests {
 
     #[test]
     fn two_operator_committee_is_explicitly_unsupported() {
+        assert_eq!(shamir_threshold(2), None);
         let mut key = KeyCell::from([7_u8; 32]);
-        let rng = UnwrapErr(SysRng);
+        let rng = rand_core_06::OsRng;
         assert!(
             split_key(2, 2, &mut key, rng).is_err(),
             "two-operator committees must be rejected"