1 files changed, 27 insertions, 2 deletions
diff --git a/src/crypto/crypto.js b/src/crypto/crypto.js
index 27bbdd20..ed950d43 100644
--- a/src/crypto/crypto.js
+++ b/src/crypto/crypto.js
@@ -26,6 +26,7 @@
 
 import publicKey from './public_key';
 import * as cipher from './cipher';
+import mode from './mode';
 import { getRandomBytes } from './random';
 import ECDHSymkey from '../type/ecdh_symkey';
 import KDFParams from '../type/kdf_params';
@@ -348,7 +349,8 @@ export async function validateParams(algo, publicParams, privateParams) {
  * @async
  */
 export async function getPrefixRandom(algo) {
-  const prefixrandom = await getRandomBytes(cipher[algo].blockSize);
+  const { blockSize } = getCipher(algo);
+  const prefixrandom = await getRandomBytes(blockSize);
   const repeat = new Uint8Array([prefixrandom[prefixrandom.length - 2], prefixrandom[prefixrandom.length - 1]]);
   return util.concat([prefixrandom, repeat]);
 }
@@ -361,5 +363,28 @@ export async function getPrefixRandom(algo) {
  * @async
  */
 export function generateSessionKey(algo) {
-  return getRandomBytes(cipher[algo].keySize);
+  const { keySize } = getCipher(algo);
+  return getRandomBytes(keySize);
+}
+
+/**
+ * Get implementation of the given AEAD mode
+ * @param {enums.aead} algo
+ * @returns {Object}
+ * @throws {Error} on invalid algo
+ */
+export function getAEADMode(algo) {
+  const algoName = enums.read(enums.aead, algo);
+  return mode[algoName];
+}
+
+/**
+ * Get implementation of the given cipher
+ * @param {enums.symmetric} algo
+ * @returns {Object}
+ * @throws {Error} on invalid algo
+ */
+export function getCipher(algo) {
+  const algoName = enums.read(enums.symmetric, algo);
+  return cipher[algoName];
 }