fix!: protect evm_wallet integrity and bind key ciphertext to wallet address

Three independent failures allowed an offline attacker with DB write access
to sign transactions using a different wallet's private key:
1. evm_wallet had no HMAC envelope — aead_encrypted_id could be swapped silently.
2. AEAD used a static tag as AAD — any valid ciphertext decrypted as any wallet key.
3. No post-decryption check that the derived address matched the requested wallet.

Fix: sign_entity covers (address, aead_encrypted_id) in a single transaction;
CreateNew/Decrypt take caller-provided AAD (wallet address bytes); after decryption
signer.address() is verified against the requested wallet address.

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

@@ -12,6 +12,8 @@ use arbiter_server::{
 use diesel::{QueryDsl, SelectableHelper};
 use diesel_async::RunQueryDsl;
 
+const TEST_AAD: &[u8] = b"test-aad";
+
 #[tokio::test]
 #[test_log::test]
 async fn bootstrap() {
@@ -57,7 +59,7 @@ async fn create_new_before_bootstrap_fails() {
         .unwrap();
 
     let err = actor
-        .create_new(SafeCell::new(b"data".to_vec()))
+        .create_new(SafeCell::new(b"data".to_vec()), TEST_AAD.to_vec())
         .await
         .unwrap_err();
     assert!(matches!(err, Error::NotBootstrapped));
@@ -71,7 +73,7 @@ async fn decrypt_before_bootstrap_fails() {
         .await
         .unwrap();
 
-    let err = actor.decrypt(1).await.unwrap_err();
+    let err = actor.decrypt(1, TEST_AAD.to_vec()).await.unwrap_err();
     assert!(matches!(err, Error::NotBootstrapped));
 }
 
@@ -85,7 +87,7 @@ async fn new_restores_sealed_state() {
     let mut actor2 = Vault::new(db, GlobalActors::spawn_message_bus())
         .await
         .unwrap();
-    let err = actor2.decrypt(1).await.unwrap_err();
+    let err = actor2.decrypt(1, TEST_AAD.to_vec()).await.unwrap_err();
     assert!(matches!(err, Error::Sealed));
 }
 
@@ -97,7 +99,7 @@ async fn unseal_correct_password() {
 
     let plaintext = b"survive a restart";
     let aead_id = actor
-        .create_new(SafeCell::new(plaintext.to_vec()))
+        .create_new(SafeCell::new(plaintext.to_vec()), TEST_AAD.to_vec())
         .await
         .unwrap();
     drop(actor);
@@ -108,7 +110,7 @@ async fn unseal_correct_password() {
     let seal_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.try_unseal(seal_key).await.unwrap();
 
-    let mut decrypted = actor.decrypt(aead_id).await.unwrap();
+    let mut decrypted = actor.decrypt(aead_id, TEST_AAD.to_vec()).await.unwrap();
     assert_eq!(*decrypted.read(), plaintext);
 }
 
@@ -120,7 +122,7 @@ async fn unseal_wrong_then_correct_password() {
 
     let plaintext = b"important data";
     let aead_id = actor
-        .create_new(SafeCell::new(plaintext.to_vec()))
+        .create_new(SafeCell::new(plaintext.to_vec()), TEST_AAD.to_vec())
         .await
         .unwrap();
     drop(actor);
@@ -136,6 +138,6 @@ async fn unseal_wrong_then_correct_password() {
     let good_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.try_unseal(good_key).await.unwrap();
 
-    let mut decrypted = actor.decrypt(aead_id).await.unwrap();
+    let mut decrypted = actor.decrypt(aead_id, TEST_AAD.to_vec()).await.unwrap();
     assert_eq!(*decrypted.read(), plaintext);
 }