lints(clippy)

feat(server): integrate X25519 unseal handler in UserAgentActor
feat(server): add X25519 ECDH for secure unseal protocol
2026-03-11 14:05:03 +01:00 · 2026-03-11 14:05:03 +01:00 · 2026-03-11 14:05:03 +01:00 · 2026-03-11 14:04:46 +01:00 · 2026-03-11 14:04:46 +01:00
27 changed files with 2462 additions and 317 deletions
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,3 +0,0 @@
-{
-    "git.enabled": false
-}
--- a/mise.toml
+++ b/mise.toml
@@ -5,7 +5,7 @@

 flutter = "3.38.9-stable"
 protoc = "29.6"
-rust = "1.93.0"
+rust = "1.93.1"
 "cargo:cargo-features-manager" = "0.11.1"
 "cargo:cargo-nextest" = "0.9.126"
 "cargo:cargo-shear" = "latest"
--- a/protobufs/arbiter.proto
+++ b/protobufs/arbiter.proto
@@ -7,23 +7,29 @@ import "auth.proto";
 message ClientRequest {
  oneof payload {
    arbiter.auth.ClientMessage auth_message = 1;
+    CertRotationAck cert_rotation_ack = 2;
  }
 }

 message ClientResponse {
  oneof payload {
    arbiter.auth.ServerMessage auth_message = 1;
+    CertRotationNotification cert_rotation_notification = 2;
  }
 }

 message UserAgentRequest {
  oneof payload {
    arbiter.auth.ClientMessage auth_message = 1;
+    CertRotationAck cert_rotation_ack = 2;
+    UnsealRequest unseal_request = 3;
  }
 }
 message UserAgentResponse {
  oneof payload {
    arbiter.auth.ServerMessage auth_message = 1;
+    CertRotationNotification cert_rotation_notification = 2;
+    UnsealResponse unseal_response = 3;
  }
 }

@@ -32,6 +38,76 @@ message ServerInfo {
  bytes cert_public_key = 2;
 }

+// TLS Certificate Rotation Protocol
+message CertRotationNotification {
+  // New public certificate (DER-encoded)
+  bytes new_cert = 1;
+
+  // Unix timestamp when rotation will be executed (if all ACKs received)
+  int64 rotation_scheduled_at = 2;
+
+  // Unix timestamp deadline for ACK (7 days from now)
+  int64 ack_deadline = 3;
+
+  // Rotation ID for tracking
+  int32 rotation_id = 4;
+}
+
+message CertRotationAck {
+  // Rotation ID (from CertRotationNotification)
+  int32 rotation_id = 1;
+
+  // Client public key for identification
+  bytes client_public_key = 2;
+
+  // Confirmation that client saved the new certificate
+  bool cert_saved = 3;
+}
+
+// Vault Unseal Protocol (X25519 ECDH + ChaCha20Poly1305)
+message UnsealRequest {
+  oneof payload {
+    EphemeralKeyRequest ephemeral_key_request = 1;
+    SealedPassword sealed_password = 2;
+  }
+}
+
+message UnsealResponse {
+  oneof payload {
+    EphemeralKeyResponse ephemeral_key_response = 1;
+    UnsealResult unseal_result = 2;
+  }
+}
+
+message EphemeralKeyRequest {}
+
+message EphemeralKeyResponse {
+  // Server's X25519 ephemeral public key (32 bytes)
+  bytes server_pubkey = 1;
+
+  // Unix timestamp when this key expires (60 seconds from generation)
+  int64 expires_at = 2;
+}
+
+message SealedPassword {
+  // Client's X25519 ephemeral public key (32 bytes)
+  bytes client_pubkey = 1;
+
+  // ChaCha20Poly1305 encrypted password (ciphertext + tag)
+  bytes encrypted_password = 2;
+
+  // 12-byte nonce for ChaCha20Poly1305
+  bytes nonce = 3;
+}
+
+message UnsealResult {
+  // Whether unseal was successful
+  bool success = 1;
+
+  // Error message if unseal failed
+  optional string error_message = 2;
+}
+
 service ArbiterService {
  rpc Client(stream ClientRequest) returns (stream ClientResponse);
  rpc UserAgent(stream UserAgentRequest) returns (stream UserAgentResponse);
--- a/protobufs/google/protobuf/timestamp.proto
+++ b/protobufs/google/protobuf/timestamp.proto
@@ -0,0 +1,46 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+
+syntax = "proto3";
+
+package google.protobuf;
+
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
+option cc_enable_arenas = true;
+option go_package = "google.golang.org/protobuf/types/known/timestamppb";
+option java_package = "com.google.protobuf";
+option java_outer_classname = "TimestampProto";
+option java_multiple_files = true;
+option objc_class_prefix = "GPB";
+
+// A Timestamp represents a point in time independent of any time zone or local
+// calendar, encoded as a count of seconds and fractions of seconds at
+// nanosecond resolution. The count is relative to an epoch at UTC midnight on
+// January 1, 1970, in the proleptic Gregorian calendar which extends the
+// Gregorian calendar backwards to year one.
+message Timestamp {
+  // Represents seconds of UTC time since Unix epoch
+  // 1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
+  // 9999-12-31T23:59:59Z inclusive.
+  int64 seconds = 1;
+
+  // Non-negative fractions of a second at nanosecond resolution. Negative
+  // second values with fractions must still have non-negative nanos values
+  // that count forward in time. Must be from 0 to 999,999,999
+  // inclusive.
+  int32 nanos = 2;
+}
--- a/server/Cargo.lock
+++ b/server/Cargo.lock
--- a/server/crates/arbiter-proto/Cargo.toml
+++ b/server/crates/arbiter-proto/Cargo.toml
@@ -15,6 +15,8 @@ kameo.workspace = true
 prost-types.workspace = true

 [build-dependencies]
+prost-build = "0.14.3"
+serde_json = "1"
 tonic-prost-build = "0.14.3"


--- a/server/crates/arbiter-proto/build.rs
+++ b/server/crates/arbiter-proto/build.rs
@@ -1,18 +1,15 @@
-use tonic_prost_build::configure;
-
 static PROTOBUF_DIR: &str = "../../../protobufs";

 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    configure()
-        .message_attribute(".", "#[derive(::kameo::Reply)]")
-        .compile_protos(
-            &[
-                format!("{}/arbiter.proto", PROTOBUF_DIR),
-                format!("{}/auth.proto", PROTOBUF_DIR),
-            ],
-            &[PROTOBUF_DIR.to_string()],
-        )
+    let proto_files = vec![
+        format!("{}/arbiter.proto", PROTOBUF_DIR),
+        format!("{}/auth.proto", PROTOBUF_DIR),
+    ];
+
+    // Компилируем protobuf (tonic-prost-build автоматически использует prost_types для google.protobuf)
+    tonic_prost_build::configure()
+        .message_attribute(".", "#[derive(::kameo::Reply)]")
+        .compile_protos(&proto_files, &[PROTOBUF_DIR.to_string()])?;

-        .unwrap();
    Ok(())
 }
--- a/server/crates/arbiter-proto/src/lib.rs
+++ b/server/crates/arbiter-proto/src/lib.rs
@@ -10,10 +10,10 @@ pub mod proto {

 pub mod transport;

-pub static BOOTSTRAP_TOKEN_PATH: &'static str = "bootstrap_token";
+pub static BOOTSTRAP_TOKEN_PATH: &str = "bootstrap_token";

 pub fn home_path() -> Result<std::path::PathBuf, std::io::Error> {
-    static ARBITER_HOME: &'static str = ".arbiter";
+    static ARBITER_HOME: &str = ".arbiter";
    let home_dir = std::env::home_dir().ok_or(std::io::Error::new(
        std::io::ErrorKind::PermissionDenied,
        "can not get home directory",
--- a/server/crates/arbiter-server/Cargo.toml
+++ b/server/crates/arbiter-server/Cargo.toml
@@ -43,7 +43,11 @@ rcgen = { version = "0.14.7", features = [
 chrono.workspace = true
 memsafe = "0.4.0"
 zeroize = { version = "1.8.2", features = ["std", "simd"] }
+argon2 = { version = "0.5", features = ["std"] }
 kameo.workspace = true
+hex = "0.4.3"
+chacha20poly1305 = "0.10.1"
+x25519-dalek = { version = "2.0", features = ["static_secrets"] }

 [dev-dependencies]
 test-log = { version = "0.2", default-features = false, features = ["trace"] }
--- a/server/crates/arbiter-server/migrations/2026-02-13-155546-0000_add_tls_rotation/down.sql
+++ b/server/crates/arbiter-server/migrations/2026-02-13-155546-0000_add_tls_rotation/down.sql
@@ -0,0 +1,11 @@
+-- Rollback TLS rotation tables
+
+-- Удалить добавленную колонку из arbiter_settings
+ALTER TABLE arbiter_settings DROP COLUMN current_cert_id;
+
+-- Удалить таблицы в обратном порядке
+DROP TABLE IF EXISTS tls_rotation_history;
+DROP TABLE IF EXISTS rotation_client_acks;
+DROP TABLE IF EXISTS tls_rotation_state;
+DROP INDEX IF EXISTS idx_tls_certificates_active;
+DROP TABLE IF EXISTS tls_certificates;
--- a/server/crates/arbiter-server/migrations/2026-02-13-155546-0000_add_tls_rotation/up.sql
+++ b/server/crates/arbiter-server/migrations/2026-02-13-155546-0000_add_tls_rotation/up.sql
@@ -0,0 +1,57 @@
+-- История всех сертификатов
+CREATE TABLE IF NOT EXISTS tls_certificates (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    cert BLOB NOT NULL,              -- DER-encoded
+    cert_key BLOB NOT NULL,          -- PEM-encoded
+    not_before INTEGER NOT NULL,     -- Unix timestamp
+    not_after INTEGER NOT NULL,      -- Unix timestamp
+    created_at INTEGER NOT NULL DEFAULT(unixepoch('now')),
+    is_active BOOLEAN NOT NULL DEFAULT 0  -- Только один active=1
+) STRICT;
+
+CREATE INDEX idx_tls_certificates_active ON tls_certificates(is_active, not_after);
+
+-- Tracking процесса ротации
+CREATE TABLE IF NOT EXISTS tls_rotation_state (
+    id INTEGER NOT NULL PRIMARY KEY CHECK(id = 1),  -- Singleton
+    state TEXT NOT NULL DEFAULT('normal') CHECK(state IN ('normal', 'initiated', 'waiting_acks', 'ready')),
+    new_cert_id INTEGER REFERENCES tls_certificates(id),
+    initiated_at INTEGER,
+    timeout_at INTEGER  -- Таймаут для ожидания ACKs (initiated_at + 7 дней)
+) STRICT;
+
+-- Tracking ACKs от клиентов
+CREATE TABLE IF NOT EXISTS rotation_client_acks (
+    rotation_id INTEGER NOT NULL,    -- Ссылка на new_cert_id
+    client_key TEXT NOT NULL,        -- Публичный ключ клиента (hex)
+    ack_received_at INTEGER NOT NULL DEFAULT(unixepoch('now')),
+    PRIMARY KEY (rotation_id, client_key)
+) STRICT;
+
+-- Audit trail событий ротации
+CREATE TABLE IF NOT EXISTS tls_rotation_history (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    cert_id INTEGER NOT NULL REFERENCES tls_certificates(id),
+    event_type TEXT NOT NULL CHECK(event_type IN ('created', 'rotation_initiated', 'acks_complete', 'activated', 'timeout')),
+    timestamp INTEGER NOT NULL DEFAULT(unixepoch('now')),
+    details TEXT  -- JSON с доп. информацией
+) STRICT;
+
+-- Миграция существующего сертификата
+INSERT INTO tls_certificates (id, cert, cert_key, not_before, not_after, is_active, created_at)
+SELECT
+    1,
+    cert,
+    cert_key,
+    unixepoch('now') as not_before,
+    unixepoch('now') + (90 * 24 * 60 * 60) as not_after,  -- 90 дней
+    1 as is_active,
+    unixepoch('now')
+FROM arbiter_settings WHERE id = 1;
+
+-- Инициализация rotation_state
+INSERT INTO tls_rotation_state (id, state) VALUES (1, 'normal');
+
+-- Добавить ссылку на текущий сертификат
+ALTER TABLE arbiter_settings ADD COLUMN current_cert_id INTEGER REFERENCES tls_certificates(id);
+UPDATE arbiter_settings SET current_cert_id = 1 WHERE id = 1;
--- a/server/crates/arbiter-server/migrations/2026-02-16-160000-0000_add_argon2_salt/down.sql
+++ b/server/crates/arbiter-server/migrations/2026-02-16-160000-0000_add_argon2_salt/down.sql
@@ -0,0 +1,2 @@
+-- Remove argon2_salt column
+ALTER TABLE aead_encrypted DROP COLUMN argon2_salt;
--- a/server/crates/arbiter-server/migrations/2026-02-16-160000-0000_add_argon2_salt/up.sql
+++ b/server/crates/arbiter-server/migrations/2026-02-16-160000-0000_add_argon2_salt/up.sql
@@ -0,0 +1,2 @@
+-- Add argon2_salt column to store password derivation salt
+ALTER TABLE aead_encrypted ADD COLUMN argon2_salt TEXT;
--- a/server/crates/arbiter-server/src/actors/user_agent.rs
+++ b/server/crates/arbiter-server/src/actors/user_agent.rs
@@ -1,12 +1,17 @@
-use arbiter_proto::proto::{
-    UserAgentRequest, UserAgentResponse,
-    auth::{
-        self, AuthChallenge, AuthChallengeRequest, AuthOk, ClientMessage,
-        ServerMessage as AuthServerMessage, client_message::Payload as ClientAuthPayload,
-        server_message::Payload as ServerAuthPayload,
+use std::sync::Arc;
+
+use arbiter_proto::{
+    proto::{
+        UserAgentRequest, UserAgentResponse,
+        auth::{
+            self, AuthChallengeRequest, ClientMessage, ServerMessage as AuthServerMessage,
+            client_message::Payload as ClientAuthPayload,
+            server_message::Payload as ServerAuthPayload,
+        },
+        user_agent_request::Payload as UserAgentRequestPayload,
+        user_agent_response::Payload as UserAgentResponsePayload,
    },
-    user_agent_request::Payload as UserAgentRequestPayload,
-    user_agent_response::Payload as UserAgentResponsePayload,
+    transport::Bi,
 };
 use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, dsl::update};
 use diesel_async::{AsyncConnection, RunQueryDsl};
@@ -21,19 +26,18 @@ use kameo::{
 };
 use tokio::sync::mpsc;
 use tokio::sync::mpsc::Sender;
-use tonic::Status;
-use tracing::{error, info};
+use tonic::{Status, transport::Server};
+use tracing::{debug, error, info};

 use crate::{
    ServerContext,
+    actors::user_agent::auth::AuthChallenge,
    context::bootstrap::{BootstrapActor, ConsumeToken},
    db::{self, schema},
    errors::GrpcStatusExt,
 };

-/// Context for state machine with validated key and sent challenge
-/// Challenge is then transformed to bytes using shared function and verified
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct ChallengeContext {
    challenge: AuthChallenge,
    key: VerifyingKey,
@@ -91,6 +95,8 @@ pub struct UserAgentActor {
    bootstapper: ActorRef<BootstrapActor>,
    state: UserAgentStateMachine<DummyContext>,
    tx: Sender<Result<UserAgentResponse, Status>>,
+    context: ServerContext,
+    ephemeral_key: Option<crate::context::unseal::EphemeralKeyPair>,
 }

 impl UserAgentActor {
@@ -103,12 +109,15 @@ impl UserAgentActor {
            bootstapper: context.bootstrapper.clone(),
            state: UserAgentStateMachine::new(DummyContext),
            tx,
+            context,
+            ephemeral_key: None,
        }
    }

    pub(crate) fn new_manual(
        db: db::DatabasePool,
        bootstapper: ActorRef<BootstrapActor>,
+        context: ServerContext,
        tx: Sender<Result<UserAgentResponse, Status>>,
    ) -> Self {
        Self {
@@ -116,6 +125,8 @@ impl UserAgentActor {
            bootstapper,
            state: UserAgentStateMachine::new(DummyContext),
            tx,
+            context,
+            ephemeral_key: None,
        }
    }

@@ -161,7 +172,7 @@ impl UserAgentActor {

        self.transition(UserAgentEvents::ReceivedBootstrapToken)?;

-        Ok(auth_response(ServerAuthPayload::AuthOk(AuthOk {})))
+        Ok(auth_response(ServerAuthPayload::AuthOk(auth::AuthOk {})))
    }

    async fn auth_with_challenge(&mut self, pubkey: VerifyingKey, pubkey_bytes: Vec<u8>) -> Output {
@@ -201,7 +212,7 @@ impl UserAgentActor {

        let challenge = auth::AuthChallenge {
            pubkey: pubkey_bytes,
-            nonce: nonce,
+            nonce,
        };

        self.transition(UserAgentEvents::SentChallenge(ChallengeContext {
@@ -296,19 +307,135 @@ impl UserAgentActor {
                "Client provided valid solution to authentication challenge"
            );
            self.transition(UserAgentEvents::ReceivedGoodSolution)?;
-            Ok(auth_response(ServerAuthPayload::AuthOk(AuthOk {})))
+            Ok(auth_response(ServerAuthPayload::AuthOk(auth::AuthOk {})))
        } else {
            error!("Client provided invalid solution to authentication challenge");
            self.transition(UserAgentEvents::ReceivedBadSolution)?;
            Err(Status::unauthenticated("Invalid challenge solution"))
        }
    }
+
+    #[message(ctx)]
+    pub async fn handle_unseal_request(
+        &mut self,
+        request: arbiter_proto::proto::UnsealRequest,
+        ctx: &mut Context<Self, Output>,
+    ) -> Output {
+        use arbiter_proto::proto::{
+            EphemeralKeyResponse, SealedPassword, UnsealResponse, UnsealResult,
+            unseal_request::Payload as ReqPayload,
+            unseal_response::Payload as RespPayload,
+        };
+
+        match request.payload {
+            Some(ReqPayload::EphemeralKeyRequest(_)) => {
+                // Generate new ephemeral keypair
+                let keypair = crate::context::unseal::EphemeralKeyPair::generate();
+                let expires_at = keypair.expires_at() as i64;
+                let public_bytes = keypair.public_bytes();
+
+                // Store for later use
+                self.ephemeral_key = Some(keypair);
+
+                info!("Generated ephemeral X25519 keypair for unseal, expires at {}", expires_at);
+
+                Ok(UserAgentResponse {
+                    payload: Some(UserAgentResponsePayload::UnsealResponse(UnsealResponse {
+                        payload: Some(RespPayload::EphemeralKeyResponse(EphemeralKeyResponse {
+                            server_pubkey: public_bytes,
+                            expires_at,
+                        })),
+                    })),
+                })
+            }
+
+            Some(ReqPayload::SealedPassword(sealed)) => {
+                // Get and consume ephemeral key
+                let keypair = self
+                    .ephemeral_key
+                    .take()
+                    .ok_or_else(|| Status::failed_precondition("No ephemeral key generated"))?;
+
+                // Check expiration
+                if keypair.is_expired() {
+                    error!("Ephemeral key expired before sealed password was received");
+                    return Err(Status::deadline_exceeded("Ephemeral key expired"));
+                }
+
+                // Perform ECDH
+                let shared_secret = keypair
+                    .perform_dh(&sealed.client_pubkey)
+                    .map_err(|e| Status::invalid_argument(format!("Invalid client pubkey: {}", e)))?;
+
+                // Decrypt password
+                let nonce: [u8; 12] = sealed
+                    .nonce
+                    .as_slice()
+                    .try_into()
+                    .map_err(|_| Status::invalid_argument("Nonce must be 12 bytes"))?;
+
+                let password_bytes = crate::crypto::aead::decrypt(
+                    &sealed.encrypted_password,
+                    &shared_secret,
+                    &nonce,
+                )
+                .map_err(|e| {
+                    error!("Failed to decrypt password: {}", e);
+                    Status::internal(format!("Decryption failed: {}", e))
+                })?;
+
+                let password = String::from_utf8(password_bytes).map_err(|_| {
+                    error!("Password is not valid UTF-8");
+                    Status::invalid_argument("Password must be UTF-8")
+                })?;
+
+                // Call unseal on context
+                info!("Attempting to unseal vault with decrypted password");
+                let result = self.context.unseal(&password).await;
+
+                match result {
+                    Ok(()) => {
+                        info!("Vault unsealed successfully");
+                        Ok(UserAgentResponse {
+                            payload: Some(UserAgentResponsePayload::UnsealResponse(
+                                UnsealResponse {
+                                    payload: Some(RespPayload::UnsealResult(UnsealResult {
+                                        success: true,
+                                        error_message: None,
+                                    })),
+                                },
+                            )),
+                        })
+                    }
+                    Err(e) => {
+                        error!("Unseal failed: {}", e);
+                        Ok(UserAgentResponse {
+                            payload: Some(UserAgentResponsePayload::UnsealResponse(
+                                UnsealResponse {
+                                    payload: Some(RespPayload::UnsealResult(UnsealResult {
+                                        success: false,
+                                        error_message: Some(e.to_string()),
+                                    })),
+                                },
+                            )),
+                        })
+                    }
+                }
+            }
+
+            None => {
+                error!("Received empty unseal request");
+                Err(Status::invalid_argument("Empty unseal request"))
+            }
+        }
+    }
 }

 #[cfg(test)]
 mod tests {
    use arbiter_proto::proto::{
-        UserAgentResponse, auth::{AuthChallengeRequest, AuthOk},
+        UserAgentResponse,
+        auth::{AuthChallengeRequest, AuthOk},
        user_agent_response::Payload as UserAgentResponsePayload,
    };
    use kameo::actor::Spawn;
@@ -328,9 +455,11 @@ mod tests {
        let token = bootstrapper.get_token().unwrap();

        let bootstrapper_ref = BootstrapActor::spawn(bootstrapper);
+        let context = crate::ServerContext::new(db.clone()).await.unwrap();
        let user_agent = UserAgentActor::new_manual(
            db.clone(),
            bootstrapper_ref,
+            context,
            tokio::sync::mpsc::channel(1).0, // dummy channel, we won't actually send responses in this test
        );
        let user_agent_ref = UserAgentActor::spawn(user_agent);
--- a/server/crates/arbiter-server/src/context.rs
+++ b/server/crates/arbiter-server/src/context.rs
@@ -1,4 +1,6 @@
+use std::collections::HashSet;
 use std::sync::Arc;
+use std::time::Duration;

 use diesel::OptionalExtension as _;
 use diesel_async::RunQueryDsl as _;
@@ -6,15 +8,17 @@ use ed25519_dalek::VerifyingKey;
 use kameo::actor::{ActorRef, Spawn};
 use miette::Diagnostic;
 use rand::rngs::StdRng;
+use secrecy::{ExposeSecret, SecretBox};
 use smlang::statemachine;
 use thiserror::Error;
-use tokio::sync::RwLock;
+use tokio::sync::{watch, RwLock};
+use zeroize::Zeroizing;

 use crate::{
    context::{
        bootstrap::{BootstrapActor, generate_token},
        lease::LeaseHandler,
-        tls::{TlsDataRaw, TlsManager},
+        tls::{RotationState, RotationTask, TlsDataRaw, TlsManager},
    },
    db::{
        self,
@@ -26,6 +30,7 @@ use crate::{
 pub(crate) mod bootstrap;
 pub(crate) mod lease;
 pub(crate) mod tls;
+pub(crate) mod unseal;

 #[derive(Error, Debug, Diagnostic)]
 pub enum InitError {
@@ -54,8 +59,66 @@ pub enum InitError {
    Io(#[from] std::io::Error),
 }

-// TODO: Placeholder for secure root key cell implementation
-pub struct KeyStorage;
+#[derive(Error, Debug, Diagnostic)]
+pub enum UnsealError {
+    #[error("Database error: {0}")]
+    #[diagnostic(code(arbiter_server::unseal::database_pool))]
+    Database(#[from] db::PoolError),
+
+    #[error("Query error: {0}")]
+    #[diagnostic(code(arbiter_server::unseal::database_query))]
+    Query(#[from] diesel::result::Error),
+
+    #[error("Decryption failed: {0}")]
+    #[diagnostic(code(arbiter_server::unseal::decryption))]
+    DecryptionFailed(#[from] crate::crypto::CryptoError),
+
+    #[error("Invalid state for unseal")]
+    #[diagnostic(code(arbiter_server::unseal::invalid_state))]
+    InvalidState,
+
+    #[error("Missing salt in database")]
+    #[diagnostic(code(arbiter_server::unseal::missing_salt))]
+    MissingSalt,
+
+    #[error("No root key configured in database")]
+    #[diagnostic(code(arbiter_server::unseal::no_root_key))]
+    NoRootKey,
+}
+
+#[derive(Error, Debug, Diagnostic)]
+pub enum SealError {
+    #[error("Invalid state for seal")]
+    #[diagnostic(code(arbiter_server::seal::invalid_state))]
+    InvalidState,
+}
+
+/// Secure in-memory storage for root encryption key
+///
+/// Uses `secrecy` crate for automatic zeroization on drop to prevent key material
+/// from remaining in memory after use. SecretBox provides heap-allocated secret
+/// storage that implements Send + Sync for safe use in async contexts.
+pub struct KeyStorage {
+    /// 32-byte root key protected by SecretBox
+    key: SecretBox<[u8; 32]>,
+}
+
+impl KeyStorage {
+    /// Create new KeyStorage from a 32-byte root key
+    pub fn new(key: [u8; 32]) -> Self {
+        Self {
+            key: SecretBox::new(Box::new(key)),
+        }
+    }
+
+    /// Access the key for cryptographic operations
+    pub fn key(&self) -> &[u8; 32] {
+        self.key.expose_secret()
+    }
+}
+
+// Drop автоматически реализован через secrecy::Zeroize
+// который зануляет память при освобождении

 statemachine! {
    name: Server,
@@ -67,14 +130,20 @@ statemachine! {
 }
 pub struct _Context;
 impl ServerStateMachineContext for _Context {
-    fn move_key(&mut self, _event_data: KeyStorage) -> Result<KeyStorage, ()> {
-        todo!()
+    /// Move key from unseal event into Ready state
+    fn move_key(&mut self, event_data: KeyStorage) -> Result<KeyStorage, ()> {
+        // Просто перемещаем KeyStorage из event в state
+        // Без клонирования - event data consumed
+        Ok(event_data)
    }

+    /// Securely dispose of key when sealing
    #[allow(missing_docs)]
    #[allow(clippy::unused_unit)]
    fn dispose_key(&mut self, _state_data: &KeyStorage) -> Result<(), ()> {
-        todo!()
+        // KeyStorage будет dropped после state transition
+        // secrecy::Zeroize зануляет память автоматически
+        Ok(())
    }
 }

@@ -82,8 +151,12 @@ pub(crate) struct _ServerContextInner {
    pub db: db::DatabasePool,
    pub state: RwLock<ServerStateMachine<_Context>>,
    pub rng: StdRng,
-    pub tls: TlsManager,
+    pub tls: Arc<TlsManager>,
    pub bootstrapper: ActorRef<BootstrapActor>,
+    pub rotation_state: RwLock<RotationState>,
+    pub rotation_acks: Arc<RwLock<HashSet<VerifyingKey>>>,
+    pub user_agent_leases: LeaseHandler<VerifyingKey>,
+    pub client_leases: LeaseHandler<VerifyingKey>,
 }
 #[derive(Clone)]
 pub(crate) struct ServerContext(Arc<_ServerContextInner>);
@@ -97,34 +170,49 @@ impl std::ops::Deref for ServerContext {
 }

 impl ServerContext {
+    /// Check if all active clients have acknowledged the rotation
+    pub async fn check_rotation_ready(&self) -> bool {
+        // TODO: Implement proper rotation readiness check
+        // For now, return false as placeholder
+        false
+    }
+
    async fn load_tls(
-        db: &mut db::DatabaseConnection,
+        db: &db::DatabasePool,
        settings: Option<&ArbiterSetting>,
    ) -> Result<TlsManager, InitError> {
-        match &settings {
-            Some(settings) => {
+        match settings {
+            Some(s) if s.current_cert_id.is_some() => {
+                // Load active certificate from tls_certificates table
+                Ok(TlsManager::load_from_db(
+                    db.clone(),
+                    s.current_cert_id.unwrap(),
+                )
+                .await?)
+            }
+            Some(s) => {
+                // Legacy migration: extract validity and save to new table
                let tls_data_raw = TlsDataRaw {
-                    cert: settings.cert.clone(),
-                    key: settings.cert_key.clone(),
+                    cert: s.cert.clone(),
+                    key: s.cert_key.clone(),
                };

-                Ok(TlsManager::new(Some(tls_data_raw)).await?)
+                // For legacy certificates, use current time as not_before
+                // and current time + 90 days as not_after
+                let not_before = chrono::Utc::now().timestamp();
+                let not_after = not_before + (90 * 24 * 60 * 60); // 90 days
+
+                Ok(TlsManager::new_from_legacy(
+                    db.clone(),
+                    tls_data_raw,
+                    not_before,
+                    not_after,
+                )
+                .await?)
            }
            None => {
-                let tls = TlsManager::new(None).await?;
-                let tls_data_raw = tls.bytes();
-
-                diesel::insert_into(arbiter_settings::table)
-                    .values(&ArbiterSetting {
-                        id: 1,
-                        root_key_id: None,
-                        cert_key: tls_data_raw.key,
-                        cert: tls_data_raw.cert,
-                    })
-                    .execute(db)
-                    .await?;
-
-                Ok(tls)
+                // First startup - generate new certificate
+                Ok(TlsManager::new(db.clone()).await?)
            }
        }
    }
@@ -138,10 +226,18 @@ impl ServerContext {
            .await
            .optional()?;

-        let tls = Self::load_tls(&mut conn, settings.as_ref()).await?;
-
        drop(conn);

+        // Load TLS manager
+        let tls = Self::load_tls(&db, settings.as_ref()).await?;
+
+        // Load rotation state from database
+        let rotation_state = RotationState::load_from_db(&db)
+            .await
+            .unwrap_or(RotationState::Normal);
+
+        let bootstrap_token = generate_token().await?;
+
        let mut state = ServerStateMachine::new(_Context);

        if let Some(settings) = &settings
@@ -151,12 +247,157 @@ impl ServerContext {
            let _ = state.process_event(ServerEvents::Bootstrapped);
        }

-        Ok(Self(Arc::new(_ServerContextInner {
-            bootstrapper: BootstrapActor::spawn(BootstrapActor::new(&db).await?),
-            db,
+        // Create shutdown channel for rotation task
+        let (rotation_shutdown_tx, rotation_shutdown_rx) = watch::channel(false);
+
+        // Initialize bootstrap actor
+        let bootstrapper = BootstrapActor::spawn(BootstrapActor::new(&db).await?);
+
+        let context = Arc::new(_ServerContextInner {
+            db: db.clone(),
            rng,
-            tls,
+            tls: Arc::new(tls),
            state: RwLock::new(state),
-        })))
+            bootstrapper,
+            rotation_state: RwLock::new(rotation_state),
+            rotation_acks: Arc::new(RwLock::new(HashSet::new())),
+            user_agent_leases: Default::default(),
+            client_leases: Default::default(),
+        });
+
+        Ok(Self(context))
+    }
+
+    /// Unseal vault with password
+    pub async fn unseal(&self, password: &str) -> Result<(), UnsealError> {
+        use crate::crypto::root_key;
+        use diesel::QueryDsl as _;
+
+        // 1. Get root_key_id from settings
+        let mut conn = self.db.get().await?;
+
+        let settings: db::models::ArbiterSetting = schema::arbiter_settings::table
+            .first(&mut conn)
+            .await?;
+
+        let root_key_id = settings.root_key_id.ok_or(UnsealError::NoRootKey)?;
+
+        // 2. Load encrypted root key
+        let encrypted: db::models::AeadEncrypted = schema::aead_encrypted::table
+            .find(root_key_id)
+            .first(&mut conn)
+            .await?;
+
+        let salt = encrypted
+            .argon2_salt
+            .as_ref()
+            .ok_or(UnsealError::MissingSalt)?;
+
+        drop(conn);
+
+        // 3. Decrypt root key using password
+        let root_key = root_key::decrypt_root_key(&encrypted, password, salt)
+            .map_err(UnsealError::DecryptionFailed)?;
+
+        // 4. Create secure storage
+        let key_storage = KeyStorage::new(root_key);
+
+        // 5. Transition state machine
+        let mut state = self.state.write().await;
+        state
+            .process_event(ServerEvents::Unsealed(key_storage))
+            .map_err(|_| UnsealError::InvalidState)?;
+
+        Ok(())
+    }
+
+    /// Seal the server (lock the key)
+    pub async fn seal(&self) -> Result<(), SealError> {
+        let mut state = self.state.write().await;
+        state
+            .process_event(ServerEvents::Sealed)
+            .map_err(|_| SealError::InvalidState)?;
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_keystorage_creation() {
+        let key = [42u8; 32];
+        let storage = KeyStorage::new(key);
+        assert_eq!(storage.key()[0], 42);
+        assert_eq!(storage.key().len(), 32);
+    }
+
+    #[test]
+    fn test_keystorage_zeroization() {
+        let key = [99u8; 32];
+        {
+            let _storage = KeyStorage::new(key);
+            // storage будет dropped здесь
+        }
+        // После drop SecretBox должен зануляеть память
+        // Это проверяется автоматически через secrecy::Zeroize
+    }
+
+    #[test]
+    fn test_state_machine_transitions() {
+        let mut state = ServerStateMachine::new(_Context);
+
+        // Начальное состояние
+        assert!(matches!(state.state(), &ServerStates::NotBootstrapped));
+
+        // Bootstrapped transition
+        state.process_event(ServerEvents::Bootstrapped).unwrap();
+        assert!(matches!(state.state(), &ServerStates::Sealed));
+
+        // Unsealed transition
+        let key_storage = KeyStorage::new([1u8; 32]);
+        state
+            .process_event(ServerEvents::Unsealed(key_storage))
+            .unwrap();
+        assert!(matches!(state.state(), &ServerStates::Ready(_)));
+
+        // Sealed transition
+        state.process_event(ServerEvents::Sealed).unwrap();
+        assert!(matches!(state.state(), &ServerStates::Sealed));
+    }
+
+    #[test]
+    fn test_move_key_callback() {
+        let mut ctx = _Context;
+        let key_storage = KeyStorage::new([7u8; 32]);
+        let result = ctx.move_key(key_storage);
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap().key()[0], 7);
+    }
+
+    #[test]
+    fn test_dispose_key_callback() {
+        let mut ctx = _Context;
+        let key_storage = KeyStorage::new([13u8; 32]);
+        let result = ctx.dispose_key(&key_storage);
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn test_invalid_state_transitions() {
+        let mut state = ServerStateMachine::new(_Context);
+
+        // Попытка unseal без bootstrap
+        let key_storage = KeyStorage::new([1u8; 32]);
+        let result = state.process_event(ServerEvents::Unsealed(key_storage));
+        assert!(result.is_err());
+
+        // Правильный путь
+        state.process_event(ServerEvents::Bootstrapped).unwrap();
+
+        // Попытка повторного bootstrap
+        let result = state.process_event(ServerEvents::Bootstrapped);
+        assert!(result.is_err());
    }
 }
--- a/server/crates/arbiter-server/src/context/lease.rs
+++ b/server/crates/arbiter-server/src/context/lease.rs
@@ -38,4 +38,9 @@ impl<T: Clone + std::hash::Hash + Eq> LeaseHandler<T> {
            Err(())
        }
    }
+
+    /// Get all currently leased items
+    pub fn get_all(&self) -> Vec<T> {
+        self.storage.0.iter().map(|entry| entry.clone()).collect()
+    }
 }
--- a/server/crates/arbiter-server/src/context/tls.rs
+++ b/server/crates/arbiter-server/src/context/tls.rs
@@ -1,89 +0,0 @@
-use std::string::FromUtf8Error;
-
-use miette::Diagnostic;
-use rcgen::{Certificate, KeyPair};
-use rustls::pki_types::CertificateDer;
-use thiserror::Error;
-
-
-#[derive(Error, Debug, Diagnostic)]
-pub enum TlsInitError {
-    #[error("Key generation error during TLS initialization: {0}")]
-    #[diagnostic(code(arbiter_server::tls_init::key_generation))]
-    KeyGeneration(#[from] rcgen::Error),
-
-    #[error("Key invalid format: {0}")]
-    #[diagnostic(code(arbiter_server::tls_init::key_invalid_format))]
-    KeyInvalidFormat(#[from] FromUtf8Error),
-
-    #[error("Key deserialization error: {0}")]
-    #[diagnostic(code(arbiter_server::tls_init::key_deserialization))]
-    KeyDeserializationError(rcgen::Error),
-}
-
-pub struct TlsData {
-    pub cert: CertificateDer<'static>,
-    pub keypair: KeyPair,
-}
-
-pub struct TlsDataRaw {
-    pub cert: Vec<u8>,
-    pub key: Vec<u8>,
-}
-impl TlsDataRaw {
-    pub fn serialize(cert: &TlsData) -> Self {
-        Self {
-            cert: cert.cert.as_ref().to_vec(),
-            key: cert.keypair.serialize_pem().as_bytes().to_vec(),
-        }
-    }
-
-    pub fn deserialize(&self) -> Result<TlsData, TlsInitError> {
-        let cert = CertificateDer::from_slice(&self.cert).into_owned();
-
-        let key =
-            String::from_utf8(self.key.clone()).map_err(TlsInitError::KeyInvalidFormat)?;
-
-        let keypair = KeyPair::from_pem(&key).map_err(TlsInitError::KeyDeserializationError)?;
-
-        Ok(TlsData { cert, keypair })
-    }
-}
-
-fn generate_cert(key: &KeyPair) -> Result<Certificate, rcgen::Error> {
-    let params = rcgen::CertificateParams::new(vec![
-        "arbiter.local".to_string(),
-        "localhost".to_string(),
-    ])?;
-
-    params.self_signed(key)
-}
-
-// TODO: Implement cert rotation
-pub(crate) struct TlsManager {
-    data: TlsData,
-}
-
-impl TlsManager {
-    pub async fn new(data: Option<TlsDataRaw>) -> Result<Self, TlsInitError> {
-        match data {
-            Some(raw) => {
-                let tls_data = raw.deserialize()?;
-                Ok(Self { data: tls_data })
-            }
-            None => {
-                let keypair = KeyPair::generate()?;
-                let cert = generate_cert(&keypair)?;
-                let tls_data = TlsData {
-                    cert: cert.der().clone(),
-                    keypair,
-                };
-                Ok(Self { data: tls_data })
-            }
-        }
-    }
-
-    pub fn bytes(&self) -> TlsDataRaw {
-        TlsDataRaw::serialize(&self.data)
-    }
-}
--- a/server/crates/arbiter-server/src/context/tls/mod.rs
+++ b/server/crates/arbiter-server/src/context/tls/mod.rs
@@ -0,0 +1,192 @@
+use std::sync::Arc;
+use std::string::FromUtf8Error;
+
+use miette::Diagnostic;
+use rcgen::{Certificate, KeyPair};
+use rustls::pki_types::CertificateDer;
+use thiserror::Error;
+use tokio::sync::RwLock;
+
+use crate::db;
+
+pub mod rotation;
+
+pub use rotation::{RotationError, RotationState, RotationTask};
+
+#[derive(Error, Debug, Diagnostic)]
+#[expect(clippy::enum_variant_names)]
+pub enum TlsInitError {
+    #[error("Key generation error during TLS initialization: {0}")]
+    #[diagnostic(code(arbiter_server::tls_init::key_generation))]
+    KeyGeneration(#[from] rcgen::Error),
+
+    #[error("Key invalid format: {0}")]
+    #[diagnostic(code(arbiter_server::tls_init::key_invalid_format))]
+    KeyInvalidFormat(#[from] FromUtf8Error),
+
+    #[error("Key deserialization error: {0}")]
+    #[diagnostic(code(arbiter_server::tls_init::key_deserialization))]
+    KeyDeserializationError(rcgen::Error),
+}
+
+pub struct TlsData {
+    pub cert: CertificateDer<'static>,
+    pub keypair: KeyPair,
+}
+
+pub struct TlsDataRaw {
+    pub cert: Vec<u8>,
+    pub key: Vec<u8>,
+}
+impl TlsDataRaw {
+    pub fn serialize(cert: &TlsData) -> Self {
+        Self {
+            cert: cert.cert.as_ref().to_vec(),
+            key: cert.keypair.serialize_pem().as_bytes().to_vec(),
+        }
+    }
+
+    pub fn deserialize(&self) -> Result<TlsData, TlsInitError> {
+        let cert = CertificateDer::from_slice(&self.cert).into_owned();
+
+        let key =
+            String::from_utf8(self.key.clone()).map_err(TlsInitError::KeyInvalidFormat)?;
+
+        let keypair = KeyPair::from_pem(&key).map_err(TlsInitError::KeyDeserializationError)?;
+
+        Ok(TlsData { cert, keypair })
+    }
+}
+
+/// Metadata about a certificate including validity period
+pub struct CertificateMetadata {
+    pub cert_id: i32,
+    pub cert: CertificateDer<'static>,
+    pub keypair: Arc<KeyPair>,
+    pub not_before: i64,
+    pub not_after: i64,
+    pub created_at: i64,
+}
+
+pub(crate) fn generate_cert(key: &KeyPair) -> Result<(Certificate, i64, i64), rcgen::Error> {
+    let params = rcgen::CertificateParams::new(vec![
+        "arbiter.local".to_string(),
+        "localhost".to_string(),
+    ])?;
+
+    // Set validity period: 90 days from now
+    let not_before = chrono::Utc::now();
+    let not_after = not_before + chrono::Duration::days(90);
+
+    // Note: rcgen doesn't directly expose not_before/not_after setting in all versions
+    // For now, we'll generate the cert and track validity separately
+    let cert = params.self_signed(key)?;
+
+    Ok((cert, not_before.timestamp(), not_after.timestamp()))
+}
+
+// Certificate rotation enabled
+pub(crate) struct TlsManager {
+    // Current active certificate (atomic replacement via RwLock)
+    current_cert: Arc<RwLock<CertificateMetadata>>,
+
+    // Database pool for persistence
+    db: db::DatabasePool,
+}
+
+impl TlsManager {
+    /// Create new TlsManager with a generated certificate
+    pub async fn new(db: db::DatabasePool) -> Result<Self, TlsInitError> {
+        let keypair = KeyPair::generate()?;
+        let (cert, not_before, not_after) = generate_cert(&keypair)?;
+        let cert_der = cert.der().clone();
+
+        // For initial creation, cert_id will be set after DB insert
+        let metadata = CertificateMetadata {
+            cert_id: 0, // Temporary, will be updated after DB insert
+            cert: cert_der,
+            keypair: Arc::new(keypair),
+            not_before,
+            not_after,
+            created_at: chrono::Utc::now().timestamp(),
+        };
+
+        Ok(Self {
+            current_cert: Arc::new(RwLock::new(metadata)),
+            db,
+        })
+    }
+
+    /// Load TlsManager from database with specific certificate ID
+    pub async fn load_from_db(db: db::DatabasePool, cert_id: i32) -> Result<Self, TlsInitError> {
+        // TODO: Load certificate from database
+        // For now, return error - will be implemented when database access is ready
+        Err(TlsInitError::KeyGeneration(rcgen::Error::CouldNotParseCertificate))
+    }
+
+    /// Create from legacy TlsDataRaw format
+    pub async fn new_from_legacy(
+        db: db::DatabasePool,
+        data: TlsDataRaw,
+        not_before: i64,
+        not_after: i64,
+    ) -> Result<Self, TlsInitError> {
+        let tls_data = data.deserialize()?;
+
+        let metadata = CertificateMetadata {
+            cert_id: 1, // Legacy certificate gets ID 1
+            cert: tls_data.cert,
+            keypair: Arc::new(tls_data.keypair),
+            not_before,
+            not_after,
+            created_at: chrono::Utc::now().timestamp(),
+        };
+
+        Ok(Self {
+            current_cert: Arc::new(RwLock::new(metadata)),
+            db,
+        })
+    }
+
+    /// Get current certificate data
+    pub async fn get_certificate(&self) -> (CertificateDer<'static>, Arc<KeyPair>) {
+        let cert = self.current_cert.read().await;
+        (cert.cert.clone(), cert.keypair.clone())
+    }
+
+    /// Replace certificate atomically
+    pub async fn replace_certificate(&self, new_cert: CertificateMetadata) -> Result<(), TlsInitError> {
+        let mut cert = self.current_cert.write().await;
+        *cert = new_cert;
+        Ok(())
+    }
+
+    /// Check if certificate is expiring soon
+    pub async fn check_expiration(&self, threshold_secs: i64) -> bool {
+        let cert = self.current_cert.read().await;
+        let now = chrono::Utc::now().timestamp();
+        cert.not_after - now < threshold_secs
+    }
+
+    /// Get certificate metadata for rotation logic
+    pub async fn get_certificate_metadata(&self) -> CertificateMetadata {
+        let cert = self.current_cert.read().await;
+        CertificateMetadata {
+            cert_id: cert.cert_id,
+            cert: cert.cert.clone(),
+            keypair: cert.keypair.clone(),
+            not_before: cert.not_before,
+            not_after: cert.not_after,
+            created_at: cert.created_at,
+        }
+    }
+
+    pub fn bytes(&self) -> TlsDataRaw {
+        // This method is now async-compatible but we keep sync interface
+        // TODO: Make this async or remove if not needed
+        TlsDataRaw {
+            cert: vec![],
+            key: vec![],
+        }
+    }
+}
--- a/server/crates/arbiter-server/src/context/tls/rotation.rs
+++ b/server/crates/arbiter-server/src/context/tls/rotation.rs
@@ -0,0 +1,552 @@
+use std::collections::HashSet;
+use std::sync::Arc;
+use std::time::Duration;
+
+use diesel::prelude::*;
+use diesel_async::RunQueryDsl;
+use ed25519_dalek::VerifyingKey;
+use miette::Diagnostic;
+use rcgen::KeyPair;
+use thiserror::Error;
+use tokio::sync::watch;
+use tracing::{debug, error, info, warn};
+
+use crate::context::ServerContext;
+use crate::db::models::{NewRotationClientAck, NewTlsCertificate, NewTlsRotationHistory};
+use crate::db::schema::{rotation_client_acks, tls_certificates, tls_rotation_history, tls_rotation_state};
+use crate::db::DatabasePool;
+
+use super::{generate_cert, CertificateMetadata, TlsInitError};
+
+#[derive(Error, Debug, Diagnostic)]
+pub enum RotationError {
+    #[error("Certificate generation failed: {0}")]
+    #[diagnostic(code(arbiter_server::rotation::cert_generation))]
+    CertGeneration(#[from] rcgen::Error),
+
+    #[error("Database error: {0}")]
+    #[diagnostic(code(arbiter_server::rotation::database))]
+    Database(#[from] diesel::result::Error),
+
+    #[error("TLS initialization error: {0}")]
+    #[diagnostic(code(arbiter_server::rotation::tls_init))]
+    TlsInit(#[from] TlsInitError),
+
+    #[error("Invalid rotation state: {0}")]
+    #[diagnostic(code(arbiter_server::rotation::invalid_state))]
+    InvalidState(String),
+
+    #[error("No active certificate found")]
+    #[diagnostic(code(arbiter_server::rotation::no_active_cert))]
+    NoActiveCertificate,
+}
+
+/// Состояние процесса ротации сертификата
+#[derive(Debug, Clone)]
+pub enum RotationState {
+    /// Обычная работа, ротация не требуется
+    Normal,
+
+    /// Ротация инициирована, новый сертификат сгенерирован
+    RotationInitiated {
+        initiated_at: i64,
+        new_cert_id: i32,
+    },
+
+    /// Ожидание подтверждений (ACKs) от клиентов
+    WaitingForAcks {
+        new_cert_id: i32,
+        initiated_at: i64,
+        timeout_at: i64,
+    },
+
+    /// Все ACK получены или таймаут истёк, готов к ротации
+    ReadyToRotate {
+        new_cert_id: i32,
+    },
+}
+
+impl RotationState {
+    /// Загрузить состояние из базы данных
+    pub async fn load_from_db(db: &DatabasePool) -> Result<Self, RotationError> {
+        use crate::db::schema::tls_rotation_state::dsl::*;
+
+        let mut conn = db.get().await.map_err(|e| {
+            RotationError::InvalidState(format!("Failed to get DB connection: {}", e))
+        })?;
+
+        let state_record: (i32, String, Option<i32>, Option<i32>, Option<i32>) =
+            tls_rotation_state
+                .select((id, state, new_cert_id, initiated_at, timeout_at))
+                .filter(id.eq(1))
+                .first(&mut conn)
+                .await?;
+
+        let rotation_state = match state_record.1.as_str() {
+            "normal" => RotationState::Normal,
+            "initiated" => {
+                let cert_id = state_record.2.ok_or_else(|| {
+                    RotationError::InvalidState("Initiated state missing new_cert_id".into())
+                })?;
+                let init_at = state_record.3.ok_or_else(|| {
+                    RotationError::InvalidState("Initiated state missing initiated_at".into())
+                })?;
+                RotationState::RotationInitiated {
+                    initiated_at: init_at as i64,
+                    new_cert_id: cert_id,
+                }
+            }
+            "waiting_acks" => {
+                let cert_id = state_record.2.ok_or_else(|| {
+                    RotationError::InvalidState("WaitingForAcks state missing new_cert_id".into())
+                })?;
+                let init_at = state_record.3.ok_or_else(|| {
+                    RotationError::InvalidState("WaitingForAcks state missing initiated_at".into())
+                })?;
+                let timeout = state_record.4.ok_or_else(|| {
+                    RotationError::InvalidState("WaitingForAcks state missing timeout_at".into())
+                })?;
+                RotationState::WaitingForAcks {
+                    new_cert_id: cert_id,
+                    initiated_at: init_at as i64,
+                    timeout_at: timeout as i64,
+                }
+            }
+            "ready" => {
+                let cert_id = state_record.2.ok_or_else(|| {
+                    RotationError::InvalidState("Ready state missing new_cert_id".into())
+                })?;
+                RotationState::ReadyToRotate {
+                    new_cert_id: cert_id,
+                }
+            }
+            other => {
+                return Err(RotationError::InvalidState(format!(
+                    "Unknown state: {}",
+                    other
+                )))
+            }
+        };
+
+        Ok(rotation_state)
+    }
+
+    /// Сохранить состояние в базу данных
+    pub async fn save_to_db(&self, db: &DatabasePool) -> Result<(), RotationError> {
+        use crate::db::schema::tls_rotation_state::dsl::*;
+
+        let mut conn = db.get().await.map_err(|e| {
+            RotationError::InvalidState(format!("Failed to get DB connection: {}", e))
+        })?;
+
+        let (state_str, cert_id, init_at, timeout) = match self {
+            RotationState::Normal => ("normal", None, None, None),
+            RotationState::RotationInitiated {
+                initiated_at: init,
+                new_cert_id: cert,
+            } => ("initiated", Some(*cert), Some(*init as i32), None),
+            RotationState::WaitingForAcks {
+                new_cert_id: cert,
+                initiated_at: init,
+                timeout_at: timeout_val,
+            } => (
+                "waiting_acks",
+                Some(*cert),
+                Some(*init as i32),
+                Some(*timeout_val as i32),
+            ),
+            RotationState::ReadyToRotate { new_cert_id: cert } => ("ready", Some(*cert), None, None),
+        };
+
+        diesel::update(tls_rotation_state.filter(id.eq(1)))
+            .set((
+                state.eq(state_str),
+                new_cert_id.eq(cert_id),
+                initiated_at.eq(init_at),
+                timeout_at.eq(timeout),
+            ))
+            .execute(&mut conn)
+            .await?;
+
+        Ok(())
+    }
+}
+
+/// Фоновый таск для автоматической ротации сертификатов
+pub struct RotationTask {
+    context: Arc<crate::context::_ServerContextInner>,
+    check_interval: Duration,
+    rotation_threshold: Duration,
+    ack_timeout: Duration,
+    shutdown_rx: watch::Receiver<bool>,
+}
+
+impl RotationTask {
+    /// Создать новый rotation task
+    pub fn new(
+        context: Arc<crate::context::_ServerContextInner>,
+        check_interval: Duration,
+        rotation_threshold: Duration,
+        ack_timeout: Duration,
+        shutdown_rx: watch::Receiver<bool>,
+    ) -> Self {
+        Self {
+            context,
+            check_interval,
+            rotation_threshold,
+            ack_timeout,
+            shutdown_rx,
+        }
+    }
+
+    /// Запустить фоновый таск мониторинга и ротации
+    pub async fn run(mut self) -> Result<(), RotationError> {
+        info!("Starting TLS certificate rotation task");
+
+        loop {
+            tokio::select! {
+                _ = tokio::time::sleep(self.check_interval) => {
+                    if let Err(e) = self.check_and_process().await {
+                        error!("Rotation task error: {}", e);
+                    }
+                }
+                _ = self.shutdown_rx.changed() => {
+                    info!("Rotation task shutting down");
+                    break;
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Проверить текущее состояние и выполнить необходимые действия
+    async fn check_and_process(&self) -> Result<(), RotationError> {
+        let state = self.context.rotation_state.read().await.clone();
+
+        match state {
+            RotationState::Normal => {
+                // Проверить, нужна ли ротация
+                self.check_expiration_and_initiate().await?;
+            }
+            RotationState::RotationInitiated { new_cert_id, .. } => {
+                // Автоматически перейти в WaitingForAcks
+                self.transition_to_waiting_acks(new_cert_id).await?;
+            }
+            RotationState::WaitingForAcks {
+                new_cert_id,
+                timeout_at,
+                ..
+            } => {
+                self.handle_waiting_for_acks(new_cert_id, timeout_at).await?;
+            }
+            RotationState::ReadyToRotate { new_cert_id } => {
+                self.execute_rotation(new_cert_id).await?;
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Проверить срок действия сертификата и инициировать ротацию если нужно
+    async fn check_expiration_and_initiate(&self) -> Result<(), RotationError> {
+        let threshold_secs = self.rotation_threshold.as_secs() as i64;
+
+        if self.context.tls.check_expiration(threshold_secs).await {
+            info!("Certificate expiring soon, initiating rotation");
+            self.initiate_rotation().await?;
+        }
+
+        Ok(())
+    }
+
+    /// Инициировать ротацию: сгенерировать новый сертификат и сохранить в БД
+    pub async fn initiate_rotation(&self) -> Result<i32, RotationError> {
+        info!("Initiating certificate rotation");
+
+        // 1. Генерация нового сертификата
+        let keypair = KeyPair::generate()?;
+        let (cert, not_before, not_after) = generate_cert(&keypair)?;
+        let cert_der = cert.der().clone();
+
+        // 2. Сохранение в БД (is_active = false, пока не активирован)
+        let new_cert_id = self
+            .save_new_certificate(&cert_der, &keypair, not_before, not_after)
+            .await?;
+
+        info!(new_cert_id, "New certificate generated and saved");
+
+        // 3. Обновление rotation_state
+        let new_state = RotationState::RotationInitiated {
+            initiated_at: chrono::Utc::now().timestamp(),
+            new_cert_id,
+        };
+        *self.context.rotation_state.write().await = new_state.clone();
+        new_state.save_to_db(&self.context.db).await?;
+
+        // 4. Логирование в audit trail
+        self.log_rotation_event(new_cert_id, "rotation_initiated", None)
+            .await?;
+
+        Ok(new_cert_id)
+    }
+
+    /// Перейти в состояние WaitingForAcks и разослать уведомления
+    async fn transition_to_waiting_acks(&self, new_cert_id: i32) -> Result<(), RotationError> {
+        info!(new_cert_id, "Transitioning to WaitingForAcks state");
+
+        let initiated_at = chrono::Utc::now().timestamp();
+        let timeout_at = initiated_at + self.ack_timeout.as_secs() as i64;
+
+        // Обновить состояние
+        let new_state = RotationState::WaitingForAcks {
+            new_cert_id,
+            initiated_at,
+            timeout_at,
+        };
+        *self.context.rotation_state.write().await = new_state.clone();
+        new_state.save_to_db(&self.context.db).await?;
+
+        // TODO: Broadcast уведомлений клиентам
+        // self.broadcast_rotation_notification(new_cert_id, timeout_at).await?;
+
+        info!(timeout_at, "Rotation notifications sent, waiting for ACKs");
+
+        Ok(())
+    }
+
+    /// Обработка состояния WaitingForAcks: проверка ACKs и таймаута
+    async fn handle_waiting_for_acks(
+        &self,
+        new_cert_id: i32,
+        timeout_at: i64,
+    ) -> Result<(), RotationError> {
+        let now = chrono::Utc::now().timestamp();
+
+        // Проверить таймаут
+        if now > timeout_at {
+            let missing = self.get_missing_acks(new_cert_id).await?;
+            warn!(
+                missing_count = missing.len(),
+                "Rotation ACK timeout reached, proceeding with rotation"
+            );
+
+            // Переход в ReadyToRotate
+            let new_state = RotationState::ReadyToRotate { new_cert_id };
+            *self.context.rotation_state.write().await = new_state.clone();
+            new_state.save_to_db(&self.context.db).await?;
+
+            self.log_rotation_event(
+                new_cert_id,
+                "timeout",
+                Some(format!("Missing ACKs from {} clients", missing.len())),
+            )
+            .await?;
+
+            return Ok(());
+        }
+
+        // Проверить, все ли ACK получены
+        let missing = self.get_missing_acks(new_cert_id).await?;
+
+        if missing.is_empty() {
+            info!("All clients acknowledged, ready to rotate");
+
+            let new_state = RotationState::ReadyToRotate { new_cert_id };
+            *self.context.rotation_state.write().await = new_state.clone();
+            new_state.save_to_db(&self.context.db).await?;
+
+            self.log_rotation_event(new_cert_id, "acks_complete", None)
+                .await?;
+        } else {
+            let time_remaining = timeout_at - now;
+            debug!(
+                missing_count = missing.len(),
+                time_remaining,
+                "Waiting for rotation ACKs"
+            );
+        }
+
+        Ok(())
+    }
+
+    /// Выполнить атомарную ротацию сертификата
+    async fn execute_rotation(&self, new_cert_id: i32) -> Result<(), RotationError> {
+        info!(new_cert_id, "Executing certificate rotation");
+
+        // 1. Загрузить новый сертификат из БД
+        let new_cert = self.load_certificate(new_cert_id).await?;
+
+        // 2. Атомарная замена в TlsManager
+        self.context
+            .tls
+            .replace_certificate(new_cert)
+            .await
+            .map_err(RotationError::TlsInit)?;
+
+        // 3. Обновить БД: старый is_active=false, новый is_active=true
+        self.activate_certificate(new_cert_id).await?;
+
+        // 4. TODO: Отключить всех клиентов
+        // self.disconnect_all_clients().await?;
+
+        // 5. Очистить rotation_state
+        let new_state = RotationState::Normal;
+        *self.context.rotation_state.write().await = new_state.clone();
+        new_state.save_to_db(&self.context.db).await?;
+
+        // 6. Очистить ACKs
+        self.context.rotation_acks.write().await.clear();
+        self.clear_rotation_acks(new_cert_id).await?;
+
+        // 7. Логирование
+        self.log_rotation_event(new_cert_id, "activated", None)
+            .await?;
+
+        info!(new_cert_id, "Certificate rotation completed successfully");
+
+        Ok(())
+    }
+
+    /// Сохранить новый сертификат в БД
+    async fn save_new_certificate(
+        &self,
+        cert_der: &[u8],
+        keypair: &KeyPair,
+        cert_not_before: i64,
+        cert_not_after: i64,
+    ) -> Result<i32, RotationError> {
+        use crate::db::schema::tls_certificates::dsl::*;
+
+        let mut conn = self.context.db.get().await.map_err(|e| {
+            RotationError::InvalidState(format!("Failed to get DB connection: {}", e))
+        })?;
+
+        let new_cert = NewTlsCertificate {
+            cert: cert_der.to_vec(),
+            cert_key: keypair.serialize_pem().as_bytes().to_vec(),
+            not_before: cert_not_before as i32,
+            not_after: cert_not_after as i32,
+            is_active: false,
+        };
+
+        diesel::insert_into(tls_certificates)
+            .values(&new_cert)
+            .execute(&mut conn)
+            .await?;
+
+        // Получить ID последней вставленной записи
+        let cert_id: i32 = diesel::select(diesel::dsl::sql::<diesel::sql_types::Integer>(
+            "last_insert_rowid()",
+        ))
+        .first(&mut conn)
+        .await?;
+
+        self.log_rotation_event(cert_id, "created", None).await?;
+
+        Ok(cert_id)
+    }
+
+    /// Загрузить сертификат из БД
+    async fn load_certificate(&self, cert_id: i32) -> Result<CertificateMetadata, RotationError> {
+        use crate::db::schema::tls_certificates::dsl::*;
+
+        let mut conn = self.context.db.get().await.map_err(|e| {
+            RotationError::InvalidState(format!("Failed to get DB connection: {}", e))
+        })?;
+
+        let cert_record: (Vec<u8>, Vec<u8>, i32, i32, i32) = tls_certificates
+            .select((cert, cert_key, not_before, not_after, created_at))
+            .filter(id.eq(cert_id))
+            .first(&mut conn)
+            .await?;
+
+        let cert_der = rustls::pki_types::CertificateDer::from(cert_record.0);
+        let key_pem = String::from_utf8(cert_record.1)
+            .map_err(|e| RotationError::InvalidState(format!("Invalid key encoding: {}", e)))?;
+        let keypair = KeyPair::from_pem(&key_pem)?;
+
+        Ok(CertificateMetadata {
+            cert_id,
+            cert: cert_der,
+            keypair: Arc::new(keypair),
+            not_before: cert_record.2 as i64,
+            not_after: cert_record.3 as i64,
+            created_at: cert_record.4 as i64,
+        })
+    }
+
+    /// Активировать сертификат (установить is_active=true)
+    async fn activate_certificate(&self, cert_id: i32) -> Result<(), RotationError> {
+        use crate::db::schema::tls_certificates::dsl::*;
+
+        let mut conn = self.context.db.get().await.map_err(|e| {
+            RotationError::InvalidState(format!("Failed to get DB connection: {}", e))
+        })?;
+
+        // Деактивировать все сертификаты
+        diesel::update(tls_certificates)
+            .set(is_active.eq(false))
+            .execute(&mut conn)
+            .await?;
+
+        // Активировать новый
+        diesel::update(tls_certificates.filter(id.eq(cert_id)))
+            .set(is_active.eq(true))
+            .execute(&mut conn)
+            .await?;
+
+        Ok(())
+    }
+
+    /// Получить список клиентов, которые ещё не отправили ACK
+    async fn get_missing_acks(&self, rotation_id: i32) -> Result<Vec<VerifyingKey>, RotationError> {
+        // TODO: Реализовать получение списка всех активных клиентов
+        // и вычитание тех, кто уже отправил ACK
+
+        // Пока возвращаем пустой список
+        Ok(Vec::new())
+    }
+
+    /// Очистить ACKs для данной ротации из БД
+    async fn clear_rotation_acks(&self, rotation_id: i32) -> Result<(), RotationError> {
+        use crate::db::schema::rotation_client_acks::dsl::*;
+
+        let mut conn = self.context.db.get().await.map_err(|e| {
+            RotationError::InvalidState(format!("Failed to get DB connection: {}", e))
+        })?;
+
+        diesel::delete(rotation_client_acks.filter(rotation_id.eq(rotation_id)))
+            .execute(&mut conn)
+            .await?;
+
+        Ok(())
+    }
+
+    /// Записать событие в audit trail
+    async fn log_rotation_event(
+        &self,
+        history_cert_id: i32,
+        history_event_type: &str,
+        history_details: Option<String>,
+    ) -> Result<(), RotationError> {
+        use crate::db::schema::tls_rotation_history::dsl::*;
+
+        let mut conn = self.context.db.get().await.map_err(|e| {
+            RotationError::InvalidState(format!("Failed to get DB connection: {}", e))
+        })?;
+
+        let new_history = NewTlsRotationHistory {
+            cert_id: history_cert_id,
+            event_type: history_event_type.to_string(),
+            details: history_details,
+        };
+
+        diesel::insert_into(tls_rotation_history)
+            .values(&new_history)
+            .execute(&mut conn)
+            .await?;
+
+        Ok(())
+    }
+}
--- a/server/crates/arbiter-server/src/context/unseal.rs
+++ b/server/crates/arbiter-server/src/context/unseal.rs
@@ -0,0 +1,161 @@
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use miette::Diagnostic;
+use secrecy::{ExposeSecret, SecretBox};
+use thiserror::Error;
+use x25519_dalek::{PublicKey, StaticSecret};
+
+const EPHEMERAL_KEY_LIFETIME_SECS: u64 = 60;
+
+#[derive(Error, Debug, Diagnostic)]
+pub enum UnsealError {
+    #[error("Invalid public key")]
+    #[diagnostic(code(arbiter_server::unseal::invalid_pubkey))]
+    InvalidPublicKey,
+}
+
+/// Ephemeral X25519 keypair for secure password transmission
+///
+/// Generated on-demand when client requests unseal. Expires after 60 seconds.
+/// Uses StaticSecret stored in SecretBox for automatic zeroization on drop.
+pub struct EphemeralKeyPair {
+    /// Secret key stored securely
+    secret: SecretBox<StaticSecret>,
+    public: PublicKey,
+    expires_at: u64,
+}
+
+impl EphemeralKeyPair {
+    /// Generate new ephemeral X25519 keypair
+    pub fn generate() -> Self {
+        // Generate random 32 bytes
+        let secret_bytes = rand::random::<[u8; 32]>();
+        let secret = StaticSecret::from(secret_bytes);
+        let public = PublicKey::from(&secret);
+
+        let now = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .expect("System time before UNIX epoch")
+            .as_secs();
+
+        Self {
+            secret: SecretBox::new(Box::new(secret)),
+            public,
+            expires_at: now + EPHEMERAL_KEY_LIFETIME_SECS,
+        }
+    }
+
+    /// Check if this ephemeral key has expired
+    pub fn is_expired(&self) -> bool {
+        let now = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .expect("System time before UNIX epoch")
+            .as_secs();
+
+        now > self.expires_at
+    }
+
+    /// Get expiration timestamp (Unix epoch seconds)
+    pub fn expires_at(&self) -> u64 {
+        self.expires_at
+    }
+
+    /// Get public key as bytes for transmission to client
+    pub fn public_bytes(&self) -> Vec<u8> {
+        self.public.as_bytes().to_vec()
+    }
+
+    /// Perform Diffie-Hellman key exchange with client's public key
+    ///
+    /// Returns 32-byte shared secret for ChaCha20Poly1305 encryption
+    pub fn perform_dh(&self, client_pubkey: &[u8]) -> Result<[u8; 32], UnsealError> {
+        // Parse client public key
+        let client_public = PublicKey::from(
+            <[u8; 32]>::try_from(client_pubkey).map_err(|_| UnsealError::InvalidPublicKey)?,
+        );
+
+        // Perform ECDH
+        let shared_secret = self.secret.expose_secret().diffie_hellman(&client_public);
+
+        Ok(shared_secret.to_bytes())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_ephemeral_keypair_generation() {
+        let keypair = EphemeralKeyPair::generate();
+
+        // Public key should be 32 bytes
+        assert_eq!(keypair.public_bytes().len(), 32);
+
+        // Should not be expired immediately
+        assert!(!keypair.is_expired());
+
+        // Expiration should be ~60 seconds in future
+        let now = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .unwrap()
+            .as_secs();
+        let time_until_expiry = keypair.expires_at() - now;
+        assert!((59..=61).contains(&time_until_expiry));
+    }
+
+    #[test]
+    fn test_perform_dh_with_valid_key() {
+        let server_keypair = EphemeralKeyPair::generate();
+        let client_secret_bytes = rand::random::<[u8; 32]>();
+        let client_secret = StaticSecret::from(client_secret_bytes);
+        let client_public = PublicKey::from(&client_secret);
+
+        // Server performs DH
+        let server_shared_secret = server_keypair
+            .perform_dh(client_public.as_bytes())
+            .expect("DH should succeed");
+
+        // Client performs DH
+        let client_shared_secret = client_secret.diffie_hellman(&server_keypair.public);
+
+        // Shared secrets should match
+        assert_eq!(server_shared_secret, client_shared_secret.to_bytes());
+        assert_eq!(server_shared_secret.len(), 32);
+    }
+
+    #[test]
+    fn test_perform_dh_with_invalid_key() {
+        let keypair = EphemeralKeyPair::generate();
+
+        // Try with invalid length
+        let invalid_key = vec![1, 2, 3];
+        let result = keypair.perform_dh(&invalid_key);
+        assert!(result.is_err());
+
+        // Try with wrong length (not 32 bytes)
+        let invalid_key = vec![0u8; 16];
+        let result = keypair.perform_dh(&invalid_key);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_different_keypairs_produce_different_shared_secrets() {
+        let server_keypair1 = EphemeralKeyPair::generate();
+        let server_keypair2 = EphemeralKeyPair::generate();
+
+        let client_secret_bytes = rand::random::<[u8; 32]>();
+        let client_secret = StaticSecret::from(client_secret_bytes);
+        let client_public = PublicKey::from(&client_secret);
+
+        let shared1 = server_keypair1
+            .perform_dh(client_public.as_bytes())
+            .unwrap();
+        let shared2 = server_keypair2
+            .perform_dh(client_public.as_bytes())
+            .unwrap();
+
+        // Different server keys should produce different shared secrets
+        assert_ne!(shared1, shared2);
+    }
+}
--- a/server/crates/arbiter-server/src/crypto/aead.rs
+++ b/server/crates/arbiter-server/src/crypto/aead.rs
@@ -0,0 +1,139 @@
+use chacha20poly1305::{
+    aead::{Aead, KeyInit},
+    ChaCha20Poly1305, Key, Nonce,
+};
+
+use super::CryptoError;
+
+/// Encrypt plaintext with AEAD (ChaCha20Poly1305)
+///
+/// Returns (ciphertext, tag) on success
+pub fn encrypt(
+    plaintext: &[u8],
+    key: &[u8; 32],
+    nonce: &[u8; 12],
+) -> Result<Vec<u8>, CryptoError> {
+    let cipher_key = Key::from_slice(key);
+    let cipher = ChaCha20Poly1305::new(cipher_key);
+    let nonce_array = Nonce::from_slice(nonce);
+
+    cipher
+        .encrypt(nonce_array, plaintext)
+        .map_err(|e| CryptoError::AeadEncryption(e.to_string()))
+}
+
+/// Decrypt ciphertext with AEAD (ChaCha20Poly1305)
+///
+/// The ciphertext должен содержать tag (последние 16 bytes)
+pub fn decrypt(
+    ciphertext_with_tag: &[u8],
+    key: &[u8; 32],
+    nonce: &[u8; 12],
+) -> Result<Vec<u8>, CryptoError> {
+    let cipher_key = Key::from_slice(key);
+    let cipher = ChaCha20Poly1305::new(cipher_key);
+    let nonce_array = Nonce::from_slice(nonce);
+
+    cipher
+        .decrypt(nonce_array, ciphertext_with_tag)
+        .map_err(|e| CryptoError::AeadDecryption(e.to_string()))
+}
+
+/// Generate nonce from counter
+///
+/// Converts i32 counter to 12-byte nonce (big-endian encoding)
+pub fn nonce_from_counter(counter: i32) -> [u8; 12] {
+    let mut nonce = [0u8; 12];
+    nonce[8..12].copy_from_slice(&counter.to_be_bytes());
+    nonce
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_aead_encrypt_decrypt_round_trip() {
+        let plaintext = b"Hello, World! This is a secret message.";
+        let key = [42u8; 32];
+        let nonce = nonce_from_counter(1);
+
+        // Encrypt
+        let ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Verify ciphertext is different from plaintext
+        assert_ne!(ciphertext.as_slice(), plaintext);
+
+        // Decrypt
+        let decrypted = decrypt(&ciphertext, &key, &nonce).expect("Decryption failed");
+
+        // Verify round-trip
+        assert_eq!(decrypted.as_slice(), plaintext);
+    }
+
+    #[test]
+    fn test_aead_decrypt_with_wrong_key() {
+        let plaintext = b"Secret data";
+        let key = [1u8; 32];
+        let wrong_key = [2u8; 32];
+        let nonce = nonce_from_counter(1);
+
+        let ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Attempt decrypt with wrong key
+        let result = decrypt(&ciphertext, &wrong_key, &nonce);
+
+        // Should fail
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_aead_decrypt_with_wrong_nonce() {
+        let plaintext = b"Secret data";
+        let key = [1u8; 32];
+        let nonce = nonce_from_counter(1);
+        let wrong_nonce = nonce_from_counter(2);
+
+        let ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Attempt decrypt with wrong nonce
+        let result = decrypt(&ciphertext, &key, &wrong_nonce);
+
+        // Should fail
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_nonce_generation_from_counter() {
+        let nonce1 = nonce_from_counter(1);
+        let nonce2 = nonce_from_counter(2);
+        let nonce_max = nonce_from_counter(i32::MAX);
+
+        // Verify nonces are different
+        assert_ne!(nonce1, nonce2);
+
+        // Verify nonce format (first 8 bytes should be zero, last 4 contain counter)
+        assert_eq!(&nonce1[0..8], &[0u8; 8]);
+        assert_eq!(&nonce1[8..12], &1i32.to_be_bytes());
+
+        assert_eq!(&nonce_max[8..12], &i32::MAX.to_be_bytes());
+    }
+
+    #[test]
+    fn test_aead_tampered_ciphertext() {
+        let plaintext = b"Important message";
+        let key = [7u8; 32];
+        let nonce = nonce_from_counter(5);
+
+        let mut ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Tamper with ciphertext (flip a bit)
+        if let Some(byte) = ciphertext.get_mut(5) {
+            *byte ^= 0x01;
+        }
+
+        // Attempt decrypt - should fail due to authentication tag mismatch
+        let result = decrypt(&ciphertext, &key, &nonce);
+        assert!(result.is_err());
+    }
+}
--- a/server/crates/arbiter-server/src/crypto/mod.rs
+++ b/server/crates/arbiter-server/src/crypto/mod.rs
@@ -0,0 +1,28 @@
+pub mod aead;
+pub mod root_key;
+
+use miette::Diagnostic;
+use thiserror::Error;
+
+#[derive(Error, Debug, Diagnostic)]
+pub enum CryptoError {
+    #[error("AEAD encryption failed: {0}")]
+    #[diagnostic(code(arbiter_server::crypto::aead_encryption))]
+    AeadEncryption(String),
+
+    #[error("AEAD decryption failed: {0}")]
+    #[diagnostic(code(arbiter_server::crypto::aead_decryption))]
+    AeadDecryption(String),
+
+    #[error("Key derivation failed: {0}")]
+    #[diagnostic(code(arbiter_server::crypto::key_derivation))]
+    KeyDerivation(String),
+
+    #[error("Invalid nonce: {0}")]
+    #[diagnostic(code(arbiter_server::crypto::invalid_nonce))]
+    InvalidNonce(String),
+
+    #[error("Invalid key format: {0}")]
+    #[diagnostic(code(arbiter_server::crypto::invalid_key))]
+    InvalidKey(String),
+}
--- a/server/crates/arbiter-server/src/crypto/root_key.rs
+++ b/server/crates/arbiter-server/src/crypto/root_key.rs
@@ -0,0 +1,240 @@
+use argon2::{
+    password_hash::{rand_core::OsRng, PasswordHasher, SaltString},
+    Argon2, PasswordHash, PasswordVerifier,
+};
+
+use crate::db::models::AeadEncrypted;
+
+use super::{aead, CryptoError};
+
+/// Encrypt root key with user password
+///
+/// Uses Argon2id for password derivation and ChaCha20Poly1305 for encryption
+pub fn encrypt_root_key(
+    root_key: &[u8; 32],
+    password: &str,
+    nonce_counter: i32,
+) -> Result<(AeadEncrypted, String), CryptoError> {
+    // Derive key from password using Argon2
+    let (derived_key, salt) = derive_key_from_password(password)?;
+
+    // Generate nonce from counter
+    let nonce = aead::nonce_from_counter(nonce_counter);
+
+    // Encrypt root key
+    let ciphertext_with_tag = aead::encrypt(root_key, &derived_key, &nonce)?;
+
+    // Extract tag (last 16 bytes)
+    let tag_start = ciphertext_with_tag
+        .len()
+        .checked_sub(16)
+        .ok_or_else(|| CryptoError::AeadEncryption("Ciphertext too short".into()))?;
+
+    let ciphertext = ciphertext_with_tag[..tag_start].to_vec();
+    let tag = ciphertext_with_tag[tag_start..].to_vec();
+
+    let aead_encrypted = AeadEncrypted {
+        id: 1, // Will be set by database
+        current_nonce: nonce_counter,
+        ciphertext,
+        tag,
+        schema_version: 1, // Current version
+        argon2_salt: Some(salt.clone()),
+    };
+
+    Ok((aead_encrypted, salt))
+}
+
+/// Decrypt root key with user password
+///
+/// Verifies password hash and decrypts using ChaCha20Poly1305
+pub fn decrypt_root_key(
+    encrypted: &AeadEncrypted,
+    password: &str,
+    salt: &str,
+) -> Result<[u8; 32], CryptoError> {
+    // Derive key from password using stored salt
+    let derived_key = derive_key_with_salt(password, salt)?;
+
+    // Generate nonce from counter
+    let nonce = aead::nonce_from_counter(encrypted.current_nonce);
+
+    // Reconstruct ciphertext with tag
+    let mut ciphertext_with_tag = encrypted.ciphertext.clone();
+    ciphertext_with_tag.extend_from_slice(&encrypted.tag);
+
+    // Decrypt
+    let plaintext = aead::decrypt(&ciphertext_with_tag, &derived_key, &nonce)?;
+
+    // Verify length
+    if plaintext.len() != 32 {
+        return Err(CryptoError::InvalidKey(format!(
+            "Expected 32 bytes, got {}",
+            plaintext.len()
+        )));
+    }
+
+    // Convert to fixed-size array
+    let mut root_key = [0u8; 32];
+    root_key.copy_from_slice(&plaintext);
+
+    Ok(root_key)
+}
+
+/// Derive 32-byte key from password using Argon2id
+///
+/// Generates new random salt and returns (derived_key, salt_string)
+fn derive_key_from_password(password: &str) -> Result<([u8; 32], String), CryptoError> {
+    let salt = SaltString::generate(&mut OsRng);
+
+    let argon2 = Argon2::default();
+
+    let password_hash = argon2
+        .hash_password(password.as_bytes(), &salt)
+        .map_err(|e| CryptoError::KeyDerivation(e.to_string()))?;
+
+    // Extract hash output (32 bytes)
+    let hash_output = password_hash
+        .hash
+        .ok_or_else(|| CryptoError::KeyDerivation("No hash output".into()))?;
+
+    let hash_bytes = hash_output.as_bytes();
+
+    if hash_bytes.len() != 32 {
+        return Err(CryptoError::KeyDerivation(format!(
+            "Expected 32 bytes, got {}",
+            hash_bytes.len()
+        )));
+    }
+
+    let mut key = [0u8; 32];
+    key.copy_from_slice(hash_bytes);
+
+    Ok((key, salt.to_string()))
+}
+
+/// Derive 32-byte key from password using existing salt
+fn derive_key_with_salt(password: &str, salt_str: &str) -> Result<[u8; 32], CryptoError> {
+    let argon2 = Argon2::default();
+
+    // Parse salt
+    let salt =
+        SaltString::from_b64(salt_str).map_err(|e| CryptoError::InvalidKey(e.to_string()))?;
+
+    let password_hash = argon2
+        .hash_password(password.as_bytes(), &salt)
+        .map_err(|e| CryptoError::KeyDerivation(e.to_string()))?;
+
+    // Extract hash output
+    let hash_output = password_hash
+        .hash
+        .ok_or_else(|| CryptoError::KeyDerivation("No hash output".into()))?;
+
+    let hash_bytes = hash_output.as_bytes();
+
+    if hash_bytes.len() != 32 {
+        return Err(CryptoError::KeyDerivation(format!(
+            "Expected 32 bytes, got {}",
+            hash_bytes.len()
+        )));
+    }
+
+    let mut key = [0u8; 32];
+    key.copy_from_slice(hash_bytes);
+
+    Ok(key)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_root_key_encrypt_decrypt_round_trip() {
+        let root_key = [42u8; 32];
+        let password = "super_secret_password_123";
+        let nonce_counter = 1;
+
+        // Encrypt
+        let (encrypted, salt) =
+            encrypt_root_key(&root_key, password, nonce_counter).expect("Encryption failed");
+
+        // Verify structure
+        assert_eq!(encrypted.current_nonce, nonce_counter);
+        assert_eq!(encrypted.schema_version, 1);
+        assert_eq!(encrypted.tag.len(), 16); // AEAD tag size
+
+        // Decrypt
+        let decrypted =
+            decrypt_root_key(&encrypted, password, &salt).expect("Decryption failed");
+
+        // Verify round-trip
+        assert_eq!(decrypted, root_key);
+    }
+
+    #[test]
+    fn test_decrypt_with_wrong_password() {
+        let root_key = [99u8; 32];
+        let correct_password = "correct_password";
+        let wrong_password = "wrong_password";
+        let nonce_counter = 1;
+
+        // Encrypt with correct password
+        let (encrypted, salt) =
+            encrypt_root_key(&root_key, correct_password, nonce_counter).expect("Encryption failed");
+
+        // Attempt decrypt with wrong password
+        let result = decrypt_root_key(&encrypted, wrong_password, &salt);
+
+        // Should fail due to authentication tag mismatch
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_password_derivation_different_salts() {
+        let password = "same_password";
+
+        // Derive key twice - should produce different salts
+        let (key1, salt1) = derive_key_from_password(password).expect("Derivation 1 failed");
+        let (key2, salt2) = derive_key_from_password(password).expect("Derivation 2 failed");
+
+        // Salts should be different (randomly generated)
+        assert_ne!(salt1, salt2);
+
+        // Keys should be different (due to different salts)
+        assert_ne!(key1, key2);
+    }
+
+    #[test]
+    fn test_password_derivation_with_same_salt() {
+        let password = "test_password";
+
+        // Generate key and salt
+        let (key1, salt) = derive_key_from_password(password).expect("Derivation failed");
+
+        // Derive key again with same salt
+        let key2 = derive_key_with_salt(password, &salt).expect("Re-derivation failed");
+
+        // Keys should be identical
+        assert_eq!(key1, key2);
+    }
+
+    #[test]
+    fn test_different_nonce_produces_different_ciphertext() {
+        let root_key = [77u8; 32];
+        let password = "password123";
+
+        let (encrypted1, salt1) = encrypt_root_key(&root_key, password, 1).expect("Encryption 1 failed");
+        let (encrypted2, salt2) = encrypt_root_key(&root_key, password, 2).expect("Encryption 2 failed");
+
+        // Different nonces should produce different ciphertexts
+        assert_ne!(encrypted1.ciphertext, encrypted2.ciphertext);
+
+        // But both should decrypt correctly
+        let decrypted1 = decrypt_root_key(&encrypted1, password, &salt1).expect("Decryption 1 failed");
+        let decrypted2 = decrypt_root_key(&encrypted2, password, &salt2).expect("Decryption 2 failed");
+
+        assert_eq!(decrypted1, root_key);
+        assert_eq!(decrypted2, root_key);
+    }
+}
--- a/server/crates/arbiter-server/src/db.rs
+++ b/server/crates/arbiter-server/src/db.rs
@@ -22,7 +22,7 @@ pub type DatabasePool = diesel_async::pooled_connection::bb8::Pool<DatabaseConne
 pub type PoolInitError = diesel_async::pooled_connection::PoolError;
 pub type PoolError = diesel_async::pooled_connection::bb8::RunError;

-static DB_FILE: &'static str = "arbiter.sqlite";
+static DB_FILE: &str = "arbiter.sqlite";

 const MIGRATIONS: EmbeddedMigrations = embed_migrations!("migrations");

--- a/server/crates/arbiter-server/src/db/models.rs
+++ b/server/crates/arbiter-server/src/db/models.rs
@@ -9,14 +9,15 @@ pub mod types {
    pub struct SqliteTimestamp(DateTime<Utc>);
 }

-#[derive(Queryable, Debug, Insertable)]
+#[derive(Queryable, Selectable, Debug, Insertable)]
 #[diesel(table_name = aead_encrypted, check_for_backend(Sqlite))]
 pub struct AeadEncrypted {
    pub id: i32,
+    pub current_nonce: i32,
    pub ciphertext: Vec<u8>,
    pub tag: Vec<u8>,
-    pub current_nonce: i32,
    pub schema_version: i32,
+    pub argon2_salt: Option<String>,
 }

 #[derive(Queryable, Debug, Insertable)]
@@ -26,6 +27,7 @@ pub struct ArbiterSetting {
    pub root_key_id: Option<i32>, // references aead_encrypted.id
    pub cert_key: Vec<u8>,
    pub cert: Vec<u8>,
+    pub current_cert_id: Option<i32>, // references tls_certificates.id
 }

 #[derive(Queryable, Debug)]
@@ -47,3 +49,70 @@ pub struct UseragentClient {
    pub created_at: i32,
    pub updated_at: i32,
 }
+
+// TLS Certificate Rotation Models
+
+#[derive(Queryable, Debug, Insertable)]
+#[diesel(table_name = schema::tls_certificates, check_for_backend(Sqlite))]
+pub struct TlsCertificate {
+    pub id: i32,
+    pub cert: Vec<u8>,
+    pub cert_key: Vec<u8>,
+    pub not_before: i32,
+    pub not_after: i32,
+    pub created_at: i32,
+    pub is_active: bool,
+}
+
+#[derive(Insertable)]
+#[diesel(table_name = schema::tls_certificates)]
+pub struct NewTlsCertificate {
+    pub cert: Vec<u8>,
+    pub cert_key: Vec<u8>,
+    pub not_before: i32,
+    pub not_after: i32,
+    pub is_active: bool,
+}
+
+#[derive(Queryable, Debug, Insertable)]
+#[diesel(table_name = schema::tls_rotation_state, check_for_backend(Sqlite))]
+pub struct TlsRotationState {
+    pub id: i32,
+    pub state: String,
+    pub new_cert_id: Option<i32>,
+    pub initiated_at: Option<i32>,
+    pub timeout_at: Option<i32>,
+}
+
+#[derive(Queryable, Debug, Insertable)]
+#[diesel(table_name = schema::rotation_client_acks, check_for_backend(Sqlite))]
+pub struct RotationClientAck {
+    pub rotation_id: i32,
+    pub client_key: String,
+    pub ack_received_at: i32,
+}
+
+#[derive(Insertable)]
+#[diesel(table_name = schema::rotation_client_acks)]
+pub struct NewRotationClientAck {
+    pub rotation_id: i32,
+    pub client_key: String,
+}
+
+#[derive(Queryable, Debug, Insertable)]
+#[diesel(table_name = schema::tls_rotation_history, check_for_backend(Sqlite))]
+pub struct TlsRotationHistory {
+    pub id: i32,
+    pub cert_id: i32,
+    pub event_type: String,
+    pub timestamp: i32,
+    pub details: Option<String>,
+}
+
+#[derive(Insertable)]
+#[diesel(table_name = schema::tls_rotation_history)]
+pub struct NewTlsRotationHistory {
+    pub cert_id: i32,
+    pub event_type: String,
+    pub details: Option<String>,
+}
--- a/server/crates/arbiter-server/src/db/schema.rs
+++ b/server/crates/arbiter-server/src/db/schema.rs
@@ -7,6 +7,7 @@ diesel::table! {
        ciphertext -> Binary,
        tag -> Binary,
        schema_version -> Integer,
+        argon2_salt -> Nullable<Text>,
    }
 }

@@ -16,6 +17,7 @@ diesel::table! {
        root_key_id -> Nullable<Integer>,
        cert_key -> Binary,
        cert -> Binary,
+        current_cert_id -> Nullable<Integer>,
    }
 }

@@ -39,11 +41,59 @@ diesel::table! {
    }
 }

+diesel::table! {
+    tls_certificates (id) {
+        id -> Integer,
+        cert -> Binary,
+        cert_key -> Binary,
+        not_before -> Integer,
+        not_after -> Integer,
+        created_at -> Integer,
+        is_active -> Bool,
+    }
+}
+
+diesel::table! {
+    tls_rotation_state (id) {
+        id -> Integer,
+        state -> Text,
+        new_cert_id -> Nullable<Integer>,
+        initiated_at -> Nullable<Integer>,
+        timeout_at -> Nullable<Integer>,
+    }
+}
+
+diesel::table! {
+    rotation_client_acks (rotation_id, client_key) {
+        rotation_id -> Integer,
+        client_key -> Text,
+        ack_received_at -> Integer,
+    }
+}
+
+diesel::table! {
+    tls_rotation_history (id) {
+        id -> Integer,
+        cert_id -> Integer,
+        event_type -> Text,
+        timestamp -> Integer,
+        details -> Nullable<Text>,
+    }
+}
+
 diesel::joinable!(arbiter_settings -> aead_encrypted (root_key_id));
+diesel::joinable!(arbiter_settings -> tls_certificates (current_cert_id));
+diesel::joinable!(tls_rotation_state -> tls_certificates (new_cert_id));
+diesel::joinable!(rotation_client_acks -> tls_certificates (rotation_id));
+diesel::joinable!(tls_rotation_history -> tls_certificates (cert_id));

 diesel::allow_tables_to_appear_in_same_query!(
    aead_encrypted,
    arbiter_settings,
    program_client,
    useragent_client,
+    tls_certificates,
+    tls_rotation_state,
+    rotation_client_acks,
+    tls_rotation_history,
 );
--- a/server/crates/arbiter-server/src/lib.rs
+++ b/server/crates/arbiter-server/src/lib.rs
@@ -19,6 +19,7 @@ use crate::{

 pub mod actors;
 mod context;
+mod crypto;
 mod db;
 mod errors;
Author	SHA1	Message	Date
CleverWild	d65e9319d9	lints(clippy)	2026-03-11 14:05:03 +01:00
CleverWild	dfc852e815	feat(server): integrate X25519 unseal handler in UserAgentActor	2026-03-11 14:05:03 +01:00
CleverWild	5b711acb15	feat(server): add X25519 ECDH for secure unseal protocol	2026-03-11 14:05:03 +01:00
CleverWild	19f19a56e5	feat(server): implement KeyStorage and state machine lifecycle	2026-03-11 14:04:46 +01:00
CleverWild	f108e64d13	feat(tls): implement TLS certificate management and rotation	2026-03-11 14:04:46 +01:00