diff --git a/src/app/lib/enc.js b/src/app/lib/enc.js
index ce608ba9..b889766b 100644
--- a/src/app/lib/enc.js
+++ b/src/app/lib/enc.js
@@ -1,8 +1,23 @@
 /**
  * data encrypt/decrypt
+ *
+ * New format (GCM):  'gcm:<iv_hex>:<salt_hex>:<authtag_hex>:<ciphertext_hex>'
+ * Legacy format:     '<ciphertext_hex>'  (pure hex, no colons — aes-192-cbc)
+ *
+ * decrypt/decryptAsync detect the format automatically via the 'gcm:' prefix,
+ * so old data encrypted with the static IV/salt continues to work without migration.
  */
 
-const algorithmDefault = 'aes-192-cbc'
+const algorithmDefault = 'aes-256-gcm'
+
+// Legacy constants — kept only for decrypting old data (aes-192-cbc)
+const LEGACY_ALGORITHM = 'aes-192-cbc'
+const LEGACY_IV = Buffer.alloc(16, 0)
+const LEGACY_SALT = 'salt'
+const LEGACY_KEY_LENGTH = 24
+const IV_LENGTH = 12 // 12 bytes is recommended for GCM
+const SALT_LENGTH = 16
+const KEY_LENGTH = 32 // aes-256 requires a 32-byte key
 
 function scryptAsync (...args) {
   const crypto = require('crypto')
@@ -19,29 +34,42 @@ function scryptAsync (...args) {
 exports.encrypt = function (
   str = '',
   password,
-  algorithm = algorithmDefault,
-  iv = Buffer.alloc(16, 0)
+  algorithm = algorithmDefault
 ) {
   const crypto = require('crypto')
-  const key = crypto.scryptSync(password, 'salt', 24)
-  // Use `crypto.randomBytes` to generate a random iv instead of the static iv
+  const iv = crypto.randomBytes(IV_LENGTH)
+  const salt = crypto.randomBytes(SALT_LENGTH)
+  const key = crypto.scryptSync(password, salt, KEY_LENGTH)
   const cipher = crypto.createCipheriv(algorithm, key, iv)
   let encrypted = cipher.update(str, 'utf8', 'hex')
   encrypted += cipher.final('hex')
-  return encrypted
+  const authTag = cipher.getAuthTag()
+  return 'gcm:' + iv.toString('hex') + ':' + salt.toString('hex') + ':' + authTag.toString('hex') + ':' + encrypted
 }
 
 exports.decrypt = function (
   encrypted = '',
   password,
-  algorithm = algorithmDefault,
-  iv = Buffer.alloc(16, 0)
+  algorithm = algorithmDefault
 ) {
   const crypto = require('crypto')
-  // Use the async `crypto.scrypt()` instead.
-  const key = crypto.scryptSync(password, 'salt', 24)
-  const decipher = crypto.createDecipheriv(algorithm, key, iv)
-  // Encrypted using same algorithm, key and iv.
+  if (encrypted.startsWith('gcm:')) {
+    // New format: gcm:iv_hex:salt_hex:authtag_hex:ciphertext_hex
+    const parts = encrypted.split(':')
+    const iv = Buffer.from(parts[1], 'hex')
+    const salt = Buffer.from(parts[2], 'hex')
+    const authTag = Buffer.from(parts[3], 'hex')
+    const ciphertext = parts[4]
+    const key = crypto.scryptSync(password, salt, KEY_LENGTH)
+    const decipher = crypto.createDecipheriv(algorithm, key, iv)
+    decipher.setAuthTag(authTag)
+    let decrypted = decipher.update(ciphertext, 'hex', 'utf8')
+    decrypted += decipher.final('utf8')
+    return decrypted
+  }
+  // Legacy format: aes-192-cbc with static IV and salt
+  const key = crypto.scryptSync(password, LEGACY_SALT, LEGACY_KEY_LENGTH)
+  const decipher = crypto.createDecipheriv(LEGACY_ALGORITHM, key, LEGACY_IV)
   let decrypted = decipher.update(encrypted, 'hex', 'utf8')
   decrypted += decipher.final('utf8')
   return decrypted
@@ -50,29 +78,42 @@ exports.decrypt = function (
 exports.encryptAsync = async function (
   str = '',
   password,
-  algorithm = algorithmDefault,
-  iv = Buffer.alloc(16, 0)
+  algorithm = algorithmDefault
 ) {
   const crypto = require('crypto')
-  const key = await scryptAsync(password, 'salt', 24)
-  // Use `crypto.randomBytes` to generate a random iv instead of the static iv
+  const iv = crypto.randomBytes(IV_LENGTH)
+  const salt = crypto.randomBytes(SALT_LENGTH)
+  const key = await scryptAsync(password, salt, KEY_LENGTH)
   const cipher = crypto.createCipheriv(algorithm, key, iv)
   let encrypted = cipher.update(str, 'utf8', 'hex')
   encrypted += cipher.final('hex')
-  return encrypted
+  const authTag = cipher.getAuthTag()
+  return 'gcm:' + iv.toString('hex') + ':' + salt.toString('hex') + ':' + authTag.toString('hex') + ':' + encrypted
 }
 
 exports.decryptAsync = async function (
   encrypted = '',
   password,
-  algorithm = algorithmDefault,
-  iv = Buffer.alloc(16, 0)
+  algorithm = algorithmDefault
 ) {
   const crypto = require('crypto')
-  // Use the async `crypto.scrypt()` instead.
-  const key = await scryptAsync(password, 'salt', 24)
-  const decipher = crypto.createDecipheriv(algorithm, key, iv)
-  // Encrypted using same algorithm, key and iv.
+  if (encrypted.startsWith('gcm:')) {
+    // New format: gcm:iv_hex:salt_hex:authtag_hex:ciphertext_hex
+    const parts = encrypted.split(':')
+    const iv = Buffer.from(parts[1], 'hex')
+    const salt = Buffer.from(parts[2], 'hex')
+    const authTag = Buffer.from(parts[3], 'hex')
+    const ciphertext = parts[4]
+    const key = await scryptAsync(password, salt, KEY_LENGTH)
+    const decipher = crypto.createDecipheriv(algorithm, key, iv)
+    decipher.setAuthTag(authTag)
+    let decrypted = decipher.update(ciphertext, 'hex', 'utf8')
+    decrypted += decipher.final('utf8')
+    return decrypted
+  }
+  // Legacy format: aes-192-cbc with static IV and salt
+  const key = await scryptAsync(password, LEGACY_SALT, LEGACY_KEY_LENGTH)
+  const decipher = crypto.createDecipheriv(LEGACY_ALGORITHM, key, LEGACY_IV)
   let decrypted = decipher.update(encrypted, 'hex', 'utf8')
   decrypted += decipher.final('utf8')
   return decrypted