fix: reject invalid attachment salt hex instead of silent fallback

krillnotes-core/src/core/workspace/attachments.rs

@@ -421,7 +421,8 @@ impl Workspace {
         if trash_path.exists() {
             std::fs::rename(&trash_path, &enc_path)?;
         }
-        let salt_bytes = hex::decode(&meta.salt).unwrap_or_else(|_| meta.salt.as_bytes().to_vec());
+        let salt_bytes = hex::decode(&meta.salt)
+            .map_err(|_| KrillnotesError::AttachmentEncryption("invalid attachment salt hex".into()))?;
         self.storage.connection().execute(
             "INSERT OR IGNORE INTO attachments
              (id, note_id, filename, mime_type, size_bytes, hash_sha256, salt, created_at)

krillnotes-core/src/core/workspace/tests.rs

@@ -6313,3 +6313,36 @@ fn test_self_authored_ops_have_verified_by() {
         "Self-authored operations should have verified_by = identity pubkey"
     );
 }
+
+#[test]
+fn test_restore_attachment_rejects_invalid_salt_hex() {
+    let dir = tempfile::tempdir().unwrap();
+    let db_path = dir.path().join("notes.db");
+    let mut ws = Workspace::create(
+        &db_path,
+        "testpass",
+        "test-identity",
+        ed25519_dalek::SigningKey::from_bytes(&[1u8; 32]),
+        test_gate(),
+        None,
+    )
+    .unwrap();
+    let root_id = ws.list_all_notes().unwrap()[0].id.clone();
+
+    let bad_meta = AttachmentMeta {
+        id: "bad-att-id".into(),
+        note_id: root_id,
+        filename: "test.txt".into(),
+        mime_type: Some("text/plain".into()),
+        size_bytes: 0,
+        hash_sha256: "0".repeat(64),
+        salt: "not-valid-hex!!!".into(),
+        created_at: crate::core::timestamp::UnixSecs::ZERO,
+    };
+
+    let err = ws.restore_attachment(&bad_meta).unwrap_err();
+    assert!(
+        matches!(err, crate::KrillnotesError::AttachmentEncryption(_)),
+        "expected AttachmentEncryption for invalid salt hex, got: {err:?}"
+    );
+}

krillnotes-core/src/core/workspace/undo.rs

@@ -511,9 +511,8 @@ impl Workspace {
                     }
                 }
                 for att in attachments {
-                    // salt is hex-encoded in AttachmentMeta; DB stores raw bytes.
-                    let salt_bytes =
-                        hex::decode(&att.salt).unwrap_or_else(|_| att.salt.as_bytes().to_vec());
+                    let salt_bytes = hex::decode(&att.salt)
+                        .map_err(|_| KrillnotesError::AttachmentEncryption("invalid attachment salt hex".into()))?;
                     tx.execute(
                         "INSERT OR IGNORE INTO attachments
                          (id, note_id, filename, mime_type, size_bytes, hash_sha256, salt, created_at)