diff --git a/static/js/crypto.js b/static/js/crypto.js
index 57d83f1..60f8406 100644
--- a/static/js/crypto.js
+++ b/static/js/crypto.js
@@ -46,7 +46,7 @@ const PasteCrypto = (function () {
         /** Generate a new, random AES-GCM 256-bit key. */
         async generateKey() {
             return window.crypto.subtle.generateKey(
-                { name: 'AES-GCM', length: 256 },
+                { name: 'AES-GCM', length: 128 },
                 true,
                 ['encrypt', 'decrypt']
             );
@@ -61,10 +61,12 @@ const PasteCrypto = (function () {
         /** Import a base64url key string into a CryptoKey for decryption. */
         async importKey(keyBase64url) {
             const keyBytes = base64urlToArrayBuffer(keyBase64url);
+            // Support both old 256-bit and new 128-bit keys automatically
+            const keyLength = keyBytes.byteLength * 8;
             return window.crypto.subtle.importKey(
                 'raw',
                 keyBytes,
-                { name: 'AES-GCM', length: 256 },
+                { name: 'AES-GCM', length: keyLength },
                 false,
                 ['decrypt']
             );