feat(vault): add recovery passphrase handling for bootstrap and unseal processes

protobufs/operator/vault/bootstrap.proto

@@ -17,6 +17,11 @@ message ContributePassphrase {
   bytes passphrase = 1;
 }
 
+message ContributeRecoveryPassphrase {
+  int32 recovery_operator_id = 1;
+  bytes passphrase            = 2;
+}
+
 enum BootstrapResult {
   BOOTSTRAP_RESULT_UNSPECIFIED = 0;
   BOOTSTRAP_RESULT_SUCCESS = 1;
@@ -27,9 +32,10 @@ enum BootstrapResult {
 
 message Request {
   oneof payload {
-    BootstrapEncryptedKey encrypted_key = 2;
-    DeclareCommittee declare_committee = 3;
-    ContributePassphrase contribute_passphrase = 4;
+    BootstrapEncryptedKey        encrypted_key                    = 2;
+    DeclareCommittee             declare_committee                = 3;
+    ContributePassphrase         contribute_passphrase            = 4;
+    ContributeRecoveryPassphrase contribute_recovery_passphrase   = 5;
   }
 }
 

protobufs/operator/vault/unseal.proto

@@ -19,6 +19,11 @@ message ContributePassphrase {
   bytes passphrase = 1;
 }
 
+message ContributeRecoveryPassphrase {
+  int32 recovery_operator_id = 1;
+  bytes passphrase            = 2;
+}
+
 enum UnsealResult {
   UNSEAL_RESULT_UNSPECIFIED = 0;
   UNSEAL_RESULT_SUCCESS = 1;
@@ -29,9 +34,10 @@ enum UnsealResult {
 
 message Request {
   oneof payload {
-    UnsealStart start = 1;
-    UnsealEncryptedKey encrypted_key = 2;
-    ContributePassphrase contribute_passphrase = 3;
+    UnsealStart                  start                          = 1;
+    UnsealEncryptedKey           encrypted_key                  = 2;
+    ContributePassphrase         contribute_passphrase          = 3;
+    ContributeRecoveryPassphrase contribute_recovery_passphrase = 4;
   }
 }
 

server/crates/arbiter-server/migrations/2026-02-14-171124-0000_init/up.sql

@@ -246,9 +246,19 @@ create table if not exists proposal_result (
 ) STRICT;
 
 -- ===============================
--- Recovery Operators (§3.5/§3.6)
+-- Recovery Operators (§3.4/§3.5/§3.6)
 -- ===============================
 
+-- Encrypted Shamir shares for recovery operators (mirrors the `operator` table).
+create table if not exists recovery_operator (
+    id          integer not null primary key references recovery_operator_identity(id) on delete restrict,
+    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'))
+) STRICT;
+
 create table if not exists recovery_operator_identity (
     id         integer not null primary key,
     public_key blob    not null unique,

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

@@ -51,11 +51,14 @@ enum CoordinatorState {
     Idle,
     Bootstrapping {
         declared_count: usize,
+        recovery_count: usize,
         passphrases: HashMap<i32, Vec<u8>>,
+        recovery_passphrases: HashMap<i32, Vec<u8>>,
     },
     Unsealing {
         threshold: usize,
-        passphrases: HashMap<i32, Vec<u8>>,
+        ordinary_passphrases: HashMap<i32, Vec<u8>>,
+        recovery_passphrases: HashMap<i32, Vec<u8>>,
     },
 }
 
@@ -78,42 +81,83 @@ impl VaultCoordinator {
 
 const SHARE_AAD: &[u8] = b"arbiter/shamir-share/v1";
 
+fn encrypt_share(
+    passphrase_bytes: Vec<u8>,
+    share: &[u8],
+) -> Result<(Vec<u8>, Vec<u8>, Vec<u8>), Error> {
+    let mut share_salt = vec![0u8; 32];
+    OsRng.fill_bytes(&mut share_salt);
+
+    let mut passphrase_cell = SafeCell::new(passphrase_bytes);
+    let mut share_seal_key = derive_key(&mut passphrase_cell, &share_salt);
+
+    let nonce = Nonce::default();
+    let encrypted_share = share_seal_key
+        .encrypt(&nonce, SHARE_AAD, share)
+        .map_err(|_| Error::Encryption)?;
+
+    Ok((encrypted_share, nonce.to_vec(), share_salt))
+}
+
+fn decrypt_share(
+    passphrase_bytes: Vec<u8>,
+    encrypted_share: Vec<u8>,
+    share_nonce_bytes: Vec<u8>,
+    share_salt: Vec<u8>,
+    operator_id: i32,
+) -> Result<Vec<u8>, Error> {
+    let nonce = Nonce::try_from(share_nonce_bytes.as_slice()).map_err(|()| {
+        error!(operator_id, "Invalid nonce in DB");
+        Error::BrokenDatabase
+    })?;
+
+    let mut passphrase_cell = SafeCell::new(passphrase_bytes);
+    let mut share_seal_key = derive_key(&mut passphrase_cell, &share_salt);
+
+    let mut share_buffer = SafeCell::new(encrypted_share);
+    share_seal_key
+        .decrypt_in_place(&nonce, SHARE_AAD, &mut share_buffer)
+        .map_err(|_| Error::InvalidPassphrase)?;
+
+    Ok(share_buffer.read().clone())
+}
+
+/// §3.4: Split the seal key across ordinary + recovery operators.
+/// Threshold = shamir_threshold(ordinary_count); total shares = ordinary + recovery.
+/// When ordinary_count == 1 (threshold = 1), vsss-rs does not support a proper split,
+/// so each share is the seal key itself — any single participant can reconstruct.
 async fn finalize_bootstrap(
     db: db::DatabasePool,
     vault: ActorRef<Vault>,
-    passphrases: HashMap<i32, Vec<u8>>,
+    ordinary_passphrases: HashMap<i32, Vec<u8>>,
+    recovery_passphrases: HashMap<i32, Vec<u8>>,
 ) -> Result<(), Error> {
-    let total = passphrases.len();
-    let threshold = shamir_threshold(total);
+    let ordinary_count = ordinary_passphrases.len();
+    let recovery_count = recovery_passphrases.len();
+    let total = ordinary_count + recovery_count;
+    let threshold = shamir_threshold(ordinary_count);
 
-    // Generate random 32-byte seal key
     let mut seal_key_bytes = [0u8; 32];
     OsRng.fill_bytes(&mut seal_key_bytes);
 
-    // Split seal key into shares using Shamir (OsRng from rand_core 0.6, compatible with vsss-rs)
-    let shares = shamir::split_key(threshold, total, &seal_key_bytes, OsRng)
-        .map_err(|e| Error::Shamir(e.to_string()))?;
+    // threshold == 1 means any single share reconstructs the key (degenerate split).
+    // vsss-rs requires threshold >= 2, so we store the key directly in this case.
+    let shares: Vec<Vec<u8>> = if threshold >= 2 {
+        shamir::split_key(threshold, total, &seal_key_bytes, OsRng)
+            .map_err(|e| Error::Shamir(e.to_string()))?
+    } else {
+        (0..total).map(|_| seal_key_bytes.to_vec()).collect()
+    };
 
     let seal_key = KeyCell::from(seal_key_bytes);
 
     let mut conn = db.get().await?;
+    let mut shares_iter = shares.into_iter();
 
-    for ((operator_id_raw, passphrase_bytes), share) in passphrases.into_iter().zip(shares) {
-        // Generate a fresh share_salt for this operator
-        let mut share_salt = vec![0u8; 32];
-        OsRng.fill_bytes(&mut share_salt);
-
-        // Derive share encryption key from passphrase + salt
-        let mut passphrase_cell = SafeCell::new(passphrase_bytes);
-        let mut share_seal_key = derive_key(&mut passphrase_cell, &share_salt);
-
-        // Encrypt this operator's share
-        let nonce = Nonce::default();
-        let encrypted_share = share_seal_key
-            .encrypt(&nonce, SHARE_AAD, &share)
-            .map_err(|_| Error::Encryption)?;
-
-        let nonce_bytes = nonce.to_vec();
+    for (operator_id_raw, passphrase_bytes) in ordinary_passphrases {
+        let share = shares_iter.next().expect("split_key returned enough shares");
+        let (encrypted_share, nonce_bytes, share_salt) =
+            encrypt_share(passphrase_bytes, &share)?;
 
         diesel::replace_into(schema::operator::table)
             .values((
@@ -128,6 +172,24 @@ async fn finalize_bootstrap(
             .await?;
     }
 
+    for (recovery_id_raw, passphrase_bytes) in recovery_passphrases {
+        let share = shares_iter.next().expect("split_key returned enough shares");
+        let (encrypted_share, nonce_bytes, share_salt) =
+            encrypt_share(passphrase_bytes, &share)?;
+
+        diesel::replace_into(schema::recovery_operator::table)
+            .values((
+                schema::recovery_operator::id.eq(recovery_id_raw),
+                schema::recovery_operator::share.eq(&encrypted_share),
+                schema::recovery_operator::share_nonce.eq(&nonce_bytes),
+                schema::recovery_operator::share_salt.eq(&share_salt),
+                schema::recovery_operator::created_at.eq(models::SqliteTimestamp::now()),
+                schema::recovery_operator::updated_at.eq(models::SqliteTimestamp::now()),
+            ))
+            .execute(&mut conn)
+            .await?;
+    }
+
     vault
         .ask(Bootstrap { seal_key })
         .await
@@ -139,15 +201,25 @@ async fn finalize_bootstrap(
     Ok(())
 }
 
+/// §3.5: Unseal using any threshold-sized mix of ordinary + recovery shares.
 async fn finalize_unseal(
     db: db::DatabasePool,
     vault: ActorRef<Vault>,
-    passphrases: HashMap<i32, Vec<u8>>,
+    ordinary_passphrases: HashMap<i32, Vec<u8>>,
+    recovery_passphrases: HashMap<i32, Vec<u8>>,
 ) -> Result<(), Error> {
     let mut conn = db.get().await?;
+
+    // Determine whether shares were stored as raw keys (threshold=1) or vsss-rs splits (threshold>=2).
+    let ordinary_operator_count: i64 = schema::operator::table
+        .count()
+        .get_result(&mut conn)
+        .await?;
+    let threshold = shamir_threshold(ordinary_operator_count as usize);
+
     let mut shares: Vec<Vec<u8>> = Vec::new();
 
-    for (operator_id_raw, passphrase_bytes) in passphrases {
+    for (operator_id_raw, passphrase_bytes) in ordinary_passphrases {
         let (encrypted_share, share_nonce_bytes, share_salt): (Vec<u8>, Vec<u8>, Vec<u8>) =
             schema::operator::table
                 .filter(schema::operator::id.eq(Some(operator_id_raw)))
@@ -160,25 +232,45 @@ async fn finalize_unseal(
                 .await
                 .map_err(|_| Error::OperatorNotFound)?;
 
-        let nonce = Nonce::try_from(share_nonce_bytes.as_slice()).map_err(|()| {
-            error!(operator_id = operator_id_raw, "Invalid nonce in DB");
-            Error::BrokenDatabase
-        })?;
-
-        let mut passphrase_cell = SafeCell::new(passphrase_bytes);
-        let mut share_seal_key = derive_key(&mut passphrase_cell, &share_salt);
-
-        let mut share_buffer = SafeCell::new(encrypted_share);
-        share_seal_key
-            .decrypt_in_place(&nonce, SHARE_AAD, &mut share_buffer)
-            .map_err(|_| Error::InvalidPassphrase)?;
-
-        let decrypted_share = share_buffer.read().clone();
-        shares.push(decrypted_share);
+        shares.push(decrypt_share(
+            passphrase_bytes,
+            encrypted_share,
+            share_nonce_bytes,
+            share_salt,
+            operator_id_raw,
+        )?);
     }
 
-    let seal_key_bytes =
-        shamir::combine_shares(&shares).map_err(|e| Error::Shamir(e.to_string()))?;
+    for (recovery_id_raw, passphrase_bytes) in recovery_passphrases {
+        let (encrypted_share, share_nonce_bytes, share_salt): (Vec<u8>, Vec<u8>, Vec<u8>) =
+            schema::recovery_operator::table
+                .find(recovery_id_raw)
+                .select((
+                    schema::recovery_operator::share,
+                    schema::recovery_operator::share_nonce,
+                    schema::recovery_operator::share_salt,
+                ))
+                .first(&mut conn)
+                .await
+                .map_err(|_| Error::OperatorNotFound)?;
+
+        shares.push(decrypt_share(
+            passphrase_bytes,
+            encrypted_share,
+            share_nonce_bytes,
+            share_salt,
+            recovery_id_raw,
+        )?);
+    }
+
+    // When threshold==1, shares are raw 32-byte seal keys (vsss-rs cannot split 1-of-N).
+    // Any single decrypted share is the key itself.
+    let seal_key_bytes: [u8; 32] = if threshold <= 1 {
+        let raw = shares.into_iter().next().ok_or_else(|| Error::Shamir("No shares available".into()))?;
+        raw.try_into().map_err(|_| Error::Shamir("Invalid share length".into()))?
+    } else {
+        shamir::combine_shares(&shares).map_err(|e| Error::Shamir(e.to_string()))?
+    };
 
     let seal_key = KeyCell::from(seal_key_bytes);
 
@@ -213,13 +305,15 @@ impl VaultCoordinator {
         }
         self.state = CoordinatorState::Bootstrapping {
             declared_count,
+            recovery_count,
             passphrases: HashMap::new(),
+            recovery_passphrases: HashMap::new(),
         };
         Ok(())
     }
 
-    /// Phase 2 of multi-operator bootstrap: contribute a passphrase.
-    /// Returns Ok(true) when all operators contributed and bootstrap finalized.
+    /// Phase 2 of multi-operator bootstrap: ordinary operator contributes a passphrase.
+    /// Returns Ok(true) when all ordinary + recovery operators contributed and bootstrap finalized.
     #[message]
     pub async fn contribute_bootstrap(
         &mut self,
@@ -228,8 +322,9 @@ impl VaultCoordinator {
     ) -> Result<bool, Error> {
         let CoordinatorState::Bootstrapping {
             declared_count,
+            recovery_count,
             passphrases,
-            ..
+            recovery_passphrases,
         } = &mut self.state
         else {
             return Err(Error::NotBootstrapping);
@@ -239,25 +334,81 @@ impl VaultCoordinator {
             return Err(Error::DuplicateContribution);
         }
 
-        // Extract bytes immediately so state stays Sync
         let passphrase_bytes = passphrase.read().to_vec();
         passphrases.insert(operator_id, passphrase_bytes);
 
-        if passphrases.len() < *declared_count {
+        if passphrases.len() < *declared_count || recovery_passphrases.len() < *recovery_count {
             return Ok(false);
         }
 
-        let CoordinatorState::Bootstrapping { passphrases, .. } =
-            std::mem::replace(&mut self.state, CoordinatorState::Idle)
+        let CoordinatorState::Bootstrapping {
+            passphrases,
+            recovery_passphrases,
+            ..
+        } = std::mem::replace(&mut self.state, CoordinatorState::Idle)
         else {
             unreachable!()
         };
 
-        finalize_bootstrap(self.db.clone(), self.vault.clone(), passphrases).await?;
+        finalize_bootstrap(
+            self.db.clone(),
+            self.vault.clone(),
+            passphrases,
+            recovery_passphrases,
+        )
+        .await?;
         Ok(true)
     }
 
-    /// Contribute a passphrase for vault unseal.
+    /// Phase 2 of multi-operator bootstrap: recovery operator contributes a passphrase.
+    /// Returns Ok(true) when all contributors are in and bootstrap finalized.
+    #[message]
+    pub async fn contribute_recovery_bootstrap(
+        &mut self,
+        recovery_operator_id: i32,
+        mut passphrase: SafeCell<Vec<u8>>,
+    ) -> Result<bool, Error> {
+        let CoordinatorState::Bootstrapping {
+            declared_count,
+            recovery_count,
+            passphrases,
+            recovery_passphrases,
+        } = &mut self.state
+        else {
+            return Err(Error::NotBootstrapping);
+        };
+
+        if recovery_passphrases.contains_key(&recovery_operator_id) {
+            return Err(Error::DuplicateContribution);
+        }
+
+        let passphrase_bytes = passphrase.read().to_vec();
+        recovery_passphrases.insert(recovery_operator_id, passphrase_bytes);
+
+        if passphrases.len() < *declared_count || recovery_passphrases.len() < *recovery_count {
+            return Ok(false);
+        }
+
+        let CoordinatorState::Bootstrapping {
+            passphrases,
+            recovery_passphrases,
+            ..
+        } = std::mem::replace(&mut self.state, CoordinatorState::Idle)
+        else {
+            unreachable!()
+        };
+
+        finalize_bootstrap(
+            self.db.clone(),
+            self.vault.clone(),
+            passphrases,
+            recovery_passphrases,
+        )
+        .await?;
+        Ok(true)
+    }
+
+    /// Contribute a passphrase for vault unseal (ordinary operator).
     /// Returns Ok(true) when threshold reached and vault is unsealed.
     #[message]
     pub async fn contribute_unseal(
@@ -265,46 +416,105 @@ impl VaultCoordinator {
         operator_id: i32,
         mut passphrase: SafeCell<Vec<u8>>,
     ) -> Result<bool, Error> {
-        if matches!(self.state, CoordinatorState::Idle) {
-            let mut conn = self.db.get().await?;
-            let count: i64 = schema::operator::table
-                .count()
-                .get_result(&mut conn)
-                .await?;
-            let threshold = shamir_threshold(usize::try_from(count).unwrap_or_default());
-
-            self.state = CoordinatorState::Unsealing {
-                threshold,
-                passphrases: HashMap::new(),
-            };
-        }
+        self.ensure_unsealing_state().await?;
 
         let CoordinatorState::Unsealing {
             threshold,
-            passphrases,
+            ordinary_passphrases,
+            recovery_passphrases,
         } = &mut self.state
         else {
             return Err(Error::NotUnsealing);
         };
 
-        if passphrases.contains_key(&operator_id) {
+        if ordinary_passphrases.contains_key(&operator_id) {
             return Err(Error::DuplicateContribution);
         }
 
         let passphrase_bytes = passphrase.read().to_vec();
-        passphrases.insert(operator_id, passphrase_bytes);
+        ordinary_passphrases.insert(operator_id, passphrase_bytes);
 
-        if passphrases.len() < *threshold {
+        if ordinary_passphrases.len() + recovery_passphrases.len() < *threshold {
             return Ok(false);
         }
 
-        let CoordinatorState::Unsealing { passphrases, .. } =
-            std::mem::replace(&mut self.state, CoordinatorState::Idle)
+        self.do_finalize_unseal().await
+    }
+
+    /// Contribute a passphrase for vault unseal (recovery operator, §3.5).
+    /// Recovery operators may contribute during unseal when recovery is active.
+    /// Returns Ok(true) when threshold reached and vault is unsealed.
+    #[message]
+    pub async fn contribute_recovery_unseal(
+        &mut self,
+        recovery_operator_id: i32,
+        mut passphrase: SafeCell<Vec<u8>>,
+    ) -> Result<bool, Error> {
+        self.ensure_unsealing_state().await?;
+
+        let CoordinatorState::Unsealing {
+            threshold,
+            ordinary_passphrases,
+            recovery_passphrases,
+        } = &mut self.state
+        else {
+            return Err(Error::NotUnsealing);
+        };
+
+        if recovery_passphrases.contains_key(&recovery_operator_id) {
+            return Err(Error::DuplicateContribution);
+        }
+
+        let passphrase_bytes = passphrase.read().to_vec();
+        recovery_passphrases.insert(recovery_operator_id, passphrase_bytes);
+
+        if ordinary_passphrases.len() + recovery_passphrases.len() < *threshold {
+            return Ok(false);
+        }
+
+        self.do_finalize_unseal().await
+    }
+}
+
+impl VaultCoordinator {
+    /// Initializes `CoordinatorState::Unsealing` on first call if still `Idle`.
+    /// Threshold is based on ordinary operator count only (§3.4).
+    async fn ensure_unsealing_state(&mut self) -> Result<(), Error> {
+        if matches!(self.state, CoordinatorState::Idle) {
+            let mut conn = self.db.get().await?;
+            let ordinary_count: i64 = schema::operator::table
+                .count()
+                .get_result(&mut conn)
+                .await?;
+            let threshold =
+                shamir_threshold(usize::try_from(ordinary_count).unwrap_or_default());
+            self.state = CoordinatorState::Unsealing {
+                threshold,
+                ordinary_passphrases: HashMap::new(),
+                recovery_passphrases: HashMap::new(),
+            };
+        }
+        Ok(())
+    }
+
+    /// Moves state back to Idle and calls finalize_unseal.
+    async fn do_finalize_unseal(&mut self) -> Result<bool, Error> {
+        let CoordinatorState::Unsealing {
+            ordinary_passphrases,
+            recovery_passphrases,
+            ..
+        } = std::mem::replace(&mut self.state, CoordinatorState::Idle)
         else {
             unreachable!()
         };
 
-        finalize_unseal(self.db.clone(), self.vault.clone(), passphrases).await?;
+        finalize_unseal(
+            self.db.clone(),
+            self.vault.clone(),
+            ordinary_passphrases,
+            recovery_passphrases,
+        )
+        .await?;
         Ok(true)
     }
 }

server/crates/arbiter-server/src/db/schema.rs

@@ -192,6 +192,17 @@ diesel::table! {
     }
 }
 
+diesel::table! {
+    recovery_operator (id) {
+        id -> Integer,
+        share -> Binary,
+        share_nonce -> Binary,
+        share_salt -> Binary,
+        created_at -> Integer,
+        updated_at -> Integer,
+    }
+}
+
 diesel::table! {
     recovery_operator_identity (id) {
         id -> Integer,
@@ -290,6 +301,7 @@ diesel::joinable!(proposal -> operator_identity (initiator_id));
 diesel::joinable!(proposal_result -> proposal (proposal_id));
 diesel::joinable!(proposal_vote -> proposal (proposal_id));
 diesel::joinable!(proposal_vote -> operator_identity (operator_id));
+diesel::joinable!(recovery_operator -> recovery_operator_identity (id));
 diesel::joinable!(recovery_proposal_vote -> proposal (proposal_id));
 diesel::joinable!(recovery_proposal_vote -> recovery_operator_identity (recovery_operator_id));
 diesel::joinable!(recovery_wakeup_request -> operator_identity (requested_by));
@@ -297,6 +309,7 @@ diesel::joinable!(recovery_wakeup_request -> operator_identity (requested_by));
 diesel::allow_tables_to_appear_in_same_query!(
     aead_encrypted,
     proposal_result,
+    recovery_operator,
     recovery_operator_identity,
     recovery_wakeup_request,
     recovery_proposal_vote,

server/crates/arbiter-server/src/grpc/operator/vault_gate/inbound.rs

@@ -2,6 +2,7 @@ use crate::{
     grpc::{Convert, TryConvert},
     peers::operator::vault_gate::{
         self as vault_gate, HandleBootstrapEncryptedKey, HandleContributeBootstrapPassphrase,
+        HandleContributeRecoveryBootstrapPassphrase, HandleContributeRecoveryUnsealPassphrase,
         HandleContributeUnsealPassphrase, HandleDeclareCommittee, HandleHandshake,
         HandleUnsealEncryptedKey,
     },
@@ -82,6 +83,14 @@ impl TryConvert for UnsealRequestPayload {
                     },
                 ),
             ),
+            Self::ContributeRecoveryPassphrase(crp) => Ok(
+                vault_gate::Inbound::HandleContributeRecoveryUnsealPassphrase(
+                    HandleContributeRecoveryUnsealPassphrase {
+                        recovery_operator_id: crp.recovery_operator_id,
+                        passphrase: crp.passphrase,
+                    },
+                ),
+            ),
         }
     }
 }
@@ -142,6 +151,14 @@ impl TryConvert for BootstrapRequestPayload {
                     },
                 ),
             ),
+            Self::ContributeRecoveryPassphrase(crp) => Ok(
+                vault_gate::Inbound::HandleContributeRecoveryBootstrapPassphrase(
+                    HandleContributeRecoveryBootstrapPassphrase {
+                        recovery_operator_id: crp.recovery_operator_id,
+                        passphrase: crp.passphrase,
+                    },
+                ),
+            ),
         }
     }
 }

server/crates/arbiter-server/src/grpc/operator/vault_gate/outbound.rs

@@ -131,6 +131,19 @@ impl TryConvert for vault_gate::Outbound {
                 };
                 Ok(wrap_bootstrap_response(proto_result))
             }
+            Self::HandleContributeRecoveryBootstrapPassphrase(result) => {
+                let proto_result = match result {
+                    Ok(true) => ProtoBootstrapResult::Success,
+                    Ok(false) => ProtoBootstrapResult::AwaitingContributions,
+                    Err(err) => {
+                        warn!(?err, "contribute recovery bootstrap passphrase failed");
+                        return Err(Status::internal(
+                            "Failed to contribute recovery bootstrap passphrase",
+                        ));
+                    }
+                };
+                Ok(wrap_bootstrap_response(proto_result))
+            }
             Self::HandleContributeUnsealPassphrase(result) => {
                 let proto_result = match result {
                     Ok(true) => ProtoUnsealResult::Success,
@@ -144,6 +157,21 @@ impl TryConvert for vault_gate::Outbound {
                     proto_result.into(),
                 )))
             }
+            Self::HandleContributeRecoveryUnsealPassphrase(result) => {
+                let proto_result = match result {
+                    Ok(true) => ProtoUnsealResult::Success,
+                    Ok(false) => ProtoUnsealResult::AwaitingContributions,
+                    Err(err) => {
+                        warn!(?err, "contribute recovery unseal passphrase failed");
+                        return Err(Status::internal(
+                            "Failed to contribute recovery unseal passphrase",
+                        ));
+                    }
+                };
+                Ok(wrap_unseal_response(UnsealResponsePayload::Result(
+                    proto_result.into(),
+                )))
+            }
         }
     }
 }

server/crates/arbiter-server/src/peers/operator/vault_gate/mod.rs

@@ -3,7 +3,10 @@ use crate::{
     actors::{
         GlobalActors,
         vault::{self, Bootstrap, GetState, TryUnseal, VaultState, events},
-        vault_coordinator::{ContributeBootstrap, ContributeUnseal, StartBootstrap},
+        vault_coordinator::{
+            ContributeBootstrap, ContributeRecoveryBootstrap, ContributeRecoveryUnseal,
+            ContributeUnseal, StartBootstrap,
+        },
     },
     crypto::{KeyCell, integrity::{self}},
     db::DatabasePool,
@@ -266,6 +269,23 @@ impl VaultGate {
             .map_err(|_| Error::internal("VaultCoordinator unavailable"))
     }
 
+    #[message]
+    pub async fn handle_contribute_recovery_bootstrap_passphrase(
+        &mut self,
+        recovery_operator_id: i32,
+        passphrase: Vec<u8>,
+    ) -> Result<bool, Error> {
+        let passphrase_cell = SafeCell::new(passphrase);
+        self.actors
+            .vault_coordinator
+            .ask(ContributeRecoveryBootstrap {
+                recovery_operator_id,
+                passphrase: passphrase_cell,
+            })
+            .await
+            .map_err(|_| Error::internal("VaultCoordinator unavailable"))
+    }
+
     #[message]
     pub async fn handle_contribute_unseal_passphrase(
         &mut self,
@@ -281,6 +301,23 @@ impl VaultGate {
             .await
             .map_err(|_| Error::internal("VaultCoordinator unavailable"))
     }
+
+    #[message]
+    pub async fn handle_contribute_recovery_unseal_passphrase(
+        &mut self,
+        recovery_operator_id: i32,
+        passphrase: Vec<u8>,
+    ) -> Result<bool, Error> {
+        let passphrase_cell = SafeCell::new(passphrase);
+        self.actors
+            .vault_coordinator
+            .ask(ContributeRecoveryUnseal {
+                recovery_operator_id,
+                passphrase: passphrase_cell,
+            })
+            .await
+            .map_err(|_| Error::internal("VaultCoordinator unavailable"))
+    }
 }
 
 impl Message<events::Bootstrapped> for VaultGate {

server/crates/arbiter-server/tests/vault/lifecycle.rs

@@ -3,14 +3,17 @@ use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
     actors::{
         GlobalActors,
-        vault::{Error, Vault},
-        vault_coordinator::{Error as CoordinatorError, StartBootstrap, VaultCoordinator},
+        vault::{Error, GetState, Vault, VaultState},
+        vault_coordinator::{
+            ContributeBootstrap, ContributeRecoveryBootstrap, ContributeRecoveryUnseal,
+            Error as CoordinatorError, StartBootstrap, VaultCoordinator,
+        },
     },
     crypto::{KeyCell, encryption::v1::{Nonce, ROOT_KEY_TAG}},
     db::{self, models, schema},
 };
 
-use diesel::{QueryDsl, SelectableHelper};
+use diesel::{ExpressionMethods, QueryDsl, SelectableHelper, insert_into};
 use diesel_async::RunQueryDsl;
 use kameo::actor::Spawn as _;
 
@@ -167,3 +170,101 @@ async fn two_operator_vault_requires_recovery_share() {
         "expected TwoOperatorsRequireRecovery, got {err:?}"
     );
 }
+
+/// §3.4: Bootstrap with 1 ordinary + 1 recovery operator produces a valid 1-of-2 Shamir split.
+/// Both ordinary and recovery shares are stored; the vault can be unsealed with either one.
+#[tokio::test]
+#[test_log::test]
+async fn recovery_share_stored_and_used_for_unseal() {
+    let db = db::create_test_pool().await;
+    let bus = GlobalActors::spawn_message_bus();
+    let vault_ref = Vault::spawn(Vault::new(db.clone(), bus).await.unwrap());
+    let coordinator = VaultCoordinator::spawn(VaultCoordinator::new(db.clone(), vault_ref.clone()));
+
+    // Register one ordinary operator and one recovery operator in the DB
+    let ordinary_id: i32 = {
+        let mut conn = db.get().await.unwrap();
+        insert_into(schema::operator_identity::table)
+            .values(schema::operator_identity::public_key.eq(vec![1u8; 32]))
+            .returning(schema::operator_identity::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap()
+    };
+    let recovery_id: i32 = {
+        let mut conn = db.get().await.unwrap();
+        insert_into(schema::recovery_operator_identity::table)
+            .values(schema::recovery_operator_identity::public_key.eq(vec![2u8; 32]))
+            .returning(schema::recovery_operator_identity::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap()
+    };
+
+    // Declare committee: 1 ordinary + 1 recovery
+    coordinator
+        .ask(StartBootstrap {
+            operator_id: ordinary_id,
+            declared_count: 1,
+            recovery_count: 1,
+        })
+        .await
+        .unwrap();
+
+    // Recovery operator contributes first — bootstrap should not finalize yet
+    let done = coordinator
+        .ask(ContributeRecoveryBootstrap {
+            recovery_operator_id: recovery_id,
+            passphrase: SafeCell::new(b"recovery-pass".to_vec()),
+        })
+        .await
+        .unwrap();
+    assert!(!done, "should not finalize with only recovery passphrase");
+
+    // Ordinary operator contributes — now bootstrap finalizes
+    let done = coordinator
+        .ask(ContributeBootstrap {
+            operator_id: ordinary_id,
+            passphrase: SafeCell::new(b"ordinary-pass".to_vec()),
+        })
+        .await
+        .unwrap();
+    assert!(done, "should finalize once all contributors are in");
+
+    // After bootstrap, vault is Unsealed (seal key still in memory).
+    let state = vault_ref.ask(GetState {}).await.unwrap();
+    assert_eq!(state, VaultState::Unsealed);
+
+    // Verify recovery_operator row was created
+    let recovery_share_count: i64 = {
+        let mut conn = db.get().await.unwrap();
+        schema::recovery_operator::table
+            .count()
+            .get_result(&mut conn)
+            .await
+            .unwrap()
+    };
+    assert_eq!(recovery_share_count, 1);
+
+    // Simulate restart: drop vault and coordinator, create fresh vault (comes up Sealed).
+    drop(coordinator);
+    drop(vault_ref);
+    let bus2 = GlobalActors::spawn_message_bus();
+    let vault_ref2 = Vault::spawn(Vault::new(db.clone(), bus2).await.unwrap());
+    let state = vault_ref2.ask(GetState {}).await.unwrap();
+    assert_eq!(state, VaultState::Sealed);
+
+    // §3.5: Unseal using ONLY the recovery operator share (threshold = shamir_threshold(1) = 1).
+    let coordinator2 = VaultCoordinator::spawn(VaultCoordinator::new(db.clone(), vault_ref2.clone()));
+    let done = coordinator2
+        .ask(ContributeRecoveryUnseal {
+            recovery_operator_id: recovery_id,
+            passphrase: SafeCell::new(b"recovery-pass".to_vec()),
+        })
+        .await
+        .unwrap();
+    assert!(done, "recovery share alone should satisfy threshold");
+
+    let state = vault_ref2.ask(GetState {}).await.unwrap();
+    assert_eq!(state, VaultState::Unsealed);
+}