diff --git a/src/utils/crypto.ts b/src/utils/crypto.ts
index 62de8895b6..9e4b439aee 100644
--- a/src/utils/crypto.ts
+++ b/src/utils/crypto.ts
@@ -122,17 +122,16 @@ export function generateKeyPairFromSecret (secret: Uint8Array): SignKeyPair {
 
 /**
  * Generate a random ED25519 keypair
- * @rtype (raw: Boolean) => {publicKey: String | Buffer, secretKey: String | Buffer}
- * @param {Boolean} raw - Whether to return raw (binary) keys
- * @return {Object} Key pair
+ * @param raw Whether to return raw (binary) keys
+ * @return Key pair
  */
-export function generateKeyPair (raw = false): {
-  publicKey: string | Buffer
+export function generateKeyPair (raw?: true): { publicKey: Buffer, secretKey: Buffer }
+export function generateKeyPair (raw: false): { publicKey: EncodedData<'ak'>, secretKey: string }
+export function generateKeyPair (raw: boolean = false): {
+  publicKey: EncodedData<'ak'> | Buffer
   secretKey: string | Buffer
 } {
-  // <node>/apps/aens/test/aens_test_utils.erl
   const keyPair = nacl.sign.keyPair()
-
   const publicBuffer = Buffer.from(keyPair.publicKey)
   const secretBuffer = Buffer.from(keyPair.secretKey)
 
diff --git a/src/utils/encoder.ts b/src/utils/encoder.ts
index 3526ed6160..83f4991af4 100644
--- a/src/utils/encoder.ts
+++ b/src/utils/encoder.ts
@@ -94,7 +94,9 @@ export function decode (data: EncodedData<EncodingType>): Buffer {
  * @param {string} type Prefix of Transaction
  * @return {EncodedData<type>>} Encoded string Base58check or Base64check data
  */
-export function encode (data: Uint8Array, type: EncodingType): EncodedData<typeof type> {
+export function encode<Type extends EncodingType> (
+  data: Uint8Array, type: Type
+): EncodedData<Type> {
   const [, { encode }] = parseType(type)
   ensureValidLength(data, type)
   return `${type}_${encode(data)}`