Add AES-GCM

libloki/crypto.js

@@ -17,6 +17,7 @@
   class FallBackDecryptionError extends Error {}
 
   const IV_LENGTH = 16;
+  const NONCE_LENGTH = 12;
 
   async function DHEncrypt(symmetricKey, plainText) {
     const iv = libsignal.crypto.getRandomBytes(IV_LENGTH);
@@ -33,6 +34,35 @@
     return ivAndCiphertext;
   }
 
+  async function EncryptGCM(symmetricKey, plaintext) {
+
+    const nonce = crypto.getRandomValues(new Uint8Array(NONCE_LENGTH));
+
+    const key = await crypto.subtle.importKey('raw', symmetricKey, {name: 'AES-GCM'}, false, ['encrypt']);
+
+    const ciphertext = await crypto.subtle.encrypt({name: 'AES-GCM', iv: nonce, tagLength: 128}, key, plaintext);
+
+    const ivAndCiphertext = new Uint8Array(
+      NONCE_LENGTH + ciphertext.byteLength
+    );
+
+    ivAndCiphertext.set(nonce);
+    ivAndCiphertext.set(new Uint8Array(ciphertext), nonce.byteLength);
+
+    return ivAndCiphertext;
+  }
+
+  async function DecryptGCM(symmetricKey, ivAndCiphertext) {
+
+      const nonce = ivAndCiphertext.slice(0, NONCE_LENGTH);
+      const ciphertext = ivAndCiphertext.slice(NONCE_LENGTH);
+
+      const key = await crypto.subtle.importKey('raw', symmetricKey, {name: 'AES-GCM'}, false, ['decrypt']);
+
+      return await crypto.subtle.decrypt({name: 'AES-GCM', iv: nonce}, key, ciphertext);
+
+  }
+
   async function DHDecrypt(symmetricKey, ivAndCiphertext) {
     const iv = ivAndCiphertext.slice(0, IV_LENGTH);
     const ciphertext = ivAndCiphertext.slice(IV_LENGTH);
@@ -106,11 +136,17 @@
     return Multibase.decode(`${base32zCode}${snodeAddressClean}`);
   }
 
+  function generateEphemeralKeyPair() {
+    let keys = libsignal.Curve.generateKeyPair();
+    // Signal protocol prepends with "0x05"
+    keys.pubKey = keys.pubKey.slice(1);
+    return keys;
+  }
+
   class LokiSnodeChannel {
     constructor() {
-      this._ephemeralKeyPair = libsignal.Curve.generateKeyPair();
-      // Signal protocol prepends with "0x05"
-      this._ephemeralKeyPair.pubKey = this._ephemeralKeyPair.pubKey.slice(1);
+
+      this._ephemeralKeyPair = generateEphemeralKeyPair();
       this._ephemeralPubKeyHex = StringView.arrayBufferToHex(
         this._ephemeralKeyPair.pubKey
       );
@@ -474,7 +510,9 @@
 
   window.libloki.crypto = {
     DHEncrypt,
+    EncryptGCM, // AES-GCM
     DHDecrypt,
+    DecryptGCM, // AES-GCM
     FallBackSessionCipher,
     FallBackDecryptionError,
     snodeCipher,
@@ -485,6 +523,7 @@
     validateAuthorisation,
     PairingType,
     LokiSessionCipher,
+    generateEphemeralKeyPair,
     // for testing
     _LokiSnodeChannel: LokiSnodeChannel,
     _decodeSnodeAddressToPubKey: decodeSnodeAddressToPubKey,

libtextsecure/stringview.js

@@ -26,6 +26,7 @@
                 : 0;
     },
 
+    // This is not a "standard" base64, do not use!
     base64ToBytes(sBase64, nBlocksSize) {
       const sB64Enc = sBase64.replace(/[^A-Za-z0-9+/]/g, '');
       const nInLen = sB64Enc.length;