diff --git a/packages/backend/src/database/schema.registry.ts b/packages/backend/src/database/schema.registry.ts
index e2a6d1d..84ddaa7 100644
--- a/packages/backend/src/database/schema.registry.ts
+++ b/packages/backend/src/database/schema.registry.ts
@@ -58,7 +58,7 @@ export const tableDefinitions: TableDefinition[] = [
     },
     { name: 'audit_logs', sql: schemaSql.createAuditLogsTableSQL },
     // { name: 'api_keys', sql: schemaSql.createApiKeysTableSQL }, // Removed API Keys table from registry
-    { name: 'passkeys', sql: schemaSql.createPasskeysTableSQL },
+    // { name: 'passkeys', sql: schemaSql.createPasskeysTableSQL }, // Removed Passkeys table from registry
     { name: 'notification_settings', sql: schemaSql.createNotificationSettingsTableSQL },
     { name: 'users', sql: schemaSql.createUsersTableSQL },
 
diff --git a/packages/backend/src/utils/crypto.ts b/packages/backend/src/utils/crypto.ts
index f863805..15cf82e 100644
--- a/packages/backend/src/utils/crypto.ts
+++ b/packages/backend/src/utils/crypto.ts
@@ -1,41 +1,103 @@
 import crypto from 'crypto';
-import bcrypt from 'bcrypt';
+import bcrypt from 'bcrypt'; // Keep bcrypt import if needed elsewhere
 
-// Function to hash a password
+const algorithm = 'aes-256-gcm';
+const ivLength = 16; // GCM 推荐的 IV 长度为 12 或 16 字节
+const tagLength = 16; // GCM 认证标签长度
+
+/**
+ * Internal helper to get and validate the encryption key buffer on demand.
+ */
+const getEncryptionKeyBuffer = (): Buffer => {
+    const keyEnv = process.env.ENCRYPTION_KEY;
+    if (!keyEnv) {
+        // This should ideally not happen due to initializeEnvironment in index.ts
+        console.error('错误：ENCRYPTION_KEY 环境变量未设置！');
+        throw new Error('ENCRYPTION_KEY is not set.');
+    }
+    try {
+        const keyBuffer = Buffer.from(keyEnv, 'hex');
+        if (keyBuffer.length !== 32) {
+            console.error(`错误：加密密钥长度必须是 32 字节，当前长度为 ${keyBuffer.length}。`);
+            throw new Error('Invalid ENCRYPTION_KEY length.');
+        }
+        return keyBuffer;
+    } catch (error) {
+        console.error('错误：无法将 ENCRYPTION_KEY 从 hex 解码为 Buffer:', error);
+        throw new Error('Failed to decode ENCRYPTION_KEY.');
+    }
+};
+
+/**
+ * 加密文本 (例如连接密码)
+ * @param text - 需要加密的明文
+ * @returns Base64 编码的字符串，格式为 "iv:encrypted:tag" (Note: Original code concatenates directly)
+ */
+export const encrypt = (text: string): string => {
+    try {
+        const encryptionKey = getEncryptionKeyBuffer(); // Get key on demand
+        const iv = crypto.randomBytes(ivLength);
+        const cipher = crypto.createCipheriv(algorithm, encryptionKey, iv);
+        const encrypted = Buffer.concat([cipher.update(text, 'utf8'), cipher.final()]);
+        const tag = cipher.getAuthTag();
+        // 将 iv、密文和认证标签组合并编码 (Original concatenation method)
+        return Buffer.concat([iv, encrypted, tag]).toString('base64');
+    } catch (error) {
+        console.error('加密失败:', error);
+        throw new Error('加密过程中发生错误');
+    }
+};
+
+/**
+ * 解密文本
+ * @param encryptedText - Base64 编码的加密字符串 (Original concatenated format)
+ * @returns 解密后的明文
+ */
+export const decrypt = (encryptedText: string): string => {
+    try {
+        const encryptionKey = getEncryptionKeyBuffer(); // Get key on demand
+        const data = Buffer.from(encryptedText, 'base64');
+        if (data.length < ivLength + tagLength) {
+            throw new Error('无效的加密数据格式');
+        }
+
+        // 从组合数据中提取 iv、密文和认证标签
+        const iv = data.slice(0, ivLength);
+        const encrypted = data.slice(ivLength, data.length - tagLength);
+        const tag = data.slice(data.length - tagLength);
+
+        const decipher = crypto.createDecipheriv(algorithm, encryptionKey, iv);
+        decipher.setAuthTag(tag); // 设置认证标签以供验证
+
+        const decrypted = Buffer.concat([decipher.update(encrypted), decipher.final()]);
+        return decrypted.toString('utf8');
+    } catch (error) {
+        console.error('解密失败:', error);
+        // 在实际应用中，解密失败通常意味着数据被篡改或密钥错误
+        // 不应向客户端泄露具体错误细节
+        throw new Error('解密过程中发生错误或数据无效');
+    }
+};
+
+// --- Password Hashing (Keep if needed) ---
 export async function hashPassword(password: string): Promise<string> {
-    const saltRounds = 10; // Adjust salt rounds as needed for security/performance balance
+    const saltRounds = 10;
     return bcrypt.hash(password, saltRounds);
 }
-
-// Function to compare a password with a hash
 export async function comparePassword(password: string, hash: string): Promise<boolean> {
     return bcrypt.compare(password, hash);
 }
 
-// Function to generate a secure random string (e.g., for session secrets, tokens)
+// --- Secure Random String (Keep if needed) ---
 export function generateSecureRandomString(length: number = 32): string {
     return crypto.randomBytes(length).toString('hex');
 }
 
-// --- Added for WebAuthn ---
-
-/**
- * Converts an ArrayBuffer or Buffer to a Base64URL-encoded string.
- * @param buffer The ArrayBuffer or Buffer to convert.
- * @returns The Base64URL-encoded string.
- */
+// --- WebAuthn Base64URL Utilities (Can be removed if not needed elsewhere) ---
 export function bufferToBase64url(buffer: ArrayBuffer | Buffer): string {
     const buf = Buffer.isBuffer(buffer) ? buffer : Buffer.from(buffer);
     return buf.toString('base64url');
 }
-
-/**
- * Converts a Base64URL-encoded string back to a Buffer.
- * @param base64urlString The Base64URL-encoded string.
- * @returns The corresponding Buffer.
- */
 export function base64urlToBuffer(base64urlString: string): Buffer {
-    // Pad the string if necessary, as base64url might omit padding
-    // Node.js Buffer.from handles base64url directly
     return Buffer.from(base64urlString, 'base64url');
 }