Add KeyPair type for asym primitives

src/signature.ts

@@ -2,6 +2,7 @@ import {Result} from 'result'
 
 export type PrivKey = CryptoKey
 export type PubKey = CryptoKey
+export type KeyPair = [PrivKey, PubKey]
 
 const algorithm: EcdsaParams = {
     name: "ECDSA",
@@ -13,7 +14,7 @@ const algorithm: EcdsaParams = {
  * @param extractable if the keys must be extractable or not
  * @return [privkey, pubkey] keys
  */
-export async function gen_keypair(extractable: boolean = false) : Promise<[PrivKey, PubKey]> {
+export async function gen_keypair(extractable: boolean = false) : Promise<KeyPair> {
     let key = await window.crypto.subtle.generateKey(
         {
             name: "ECDSA",