JWT検証の実装

npm i jsonwebtoken jwks-rsa
npm i -D @types/jsonwebtoken

index.ts

import jwt, { JwtHeader, SigningKeyCallback } from "jsonwebtoken";
import jwksClient from "jwks-rsa";
var client = jwksClient({
  jwksUri:
    "https://cognito-idp.{region}.amazonaws.com/{userPoolId}/.well-known/jwks.json",
});

function getKey(header: JwtHeader, callback: SigningKeyCallback) {
  if (!header.kid) throw new Error("not found kid!");
  client.getSigningKey(header.kid, function (err, key) {
    if (err) throw err;
    callback(null, key.getPublicKey());
  });
}

const token = "{jwtToken}";

jwt.verify(token, getKey, function (err, decoded) {
  if (err) throw err;
  console.log(decoded);
});

npx ts-node index.ts

キャッシュについて

毎回Cognitoのjwksにアクセスしなくて良いように、デフォルトでキャッシュ有効になってます。便利！
https://github.com/auth0/node-jwks-rsa#caching

AmplifyでのJWTの取り方

import { Auth } from "aws-amplify";
.....
const session = await Auth.currentSession()
const jwt = session.getAccessToken().getJwtToken()
console.log(jwt);

JWTってJSON Web Tokenの略だから、このメソッド名Token被ってない！？