Sign in With Apple token verification fails on occassion

[akmarinov]

Issue Description

The JWT tokens that Apple issues on the client side vary with regards to the used kid, for example they can be:

  "kid": "86D88Kf",
  "kid": "eXaunmL",
  "kid": "AIDOPK1",

The code at the apple.js queries the Apple API on valid public keys and respective kids, which at this time returns

{
  "keys": [
    {
      "kty": "RSA",
      "kid": "86D88Kf",
      "use": "sig",
      "alg": "RS256",
      "n": "iGaLqP6y-SJCCBq5Hv6pGDbG_SQ11MNjH7rWHcCFYz4hGwHC4lcSurTlV8u3avoVNM8jXevG1Iu1SY11qInqUvjJur--hghr1b56OPJu6H1iKulSxGjEIyDP6c5BdE1uwprYyr4IO9th8fOwCPygjLFrh44XEGbDIFeImwvBAGOhmMB2AD1n1KviyNsH0bEB7phQtiLk-ILjv1bORSRl8AK677-1T8isGfHKXGZ_ZGtStDe7Lu0Ihp8zoUt59kx2o9uWpROkzF56ypresiIl4WprClRCjz8x6cPZXU2qNWhu71TQvUFwvIvbkE1oYaJMb0jcOTmBRZA2QuYw-zHLwQ",
      "e": "AQAB"
    },
    {
      "kty": "RSA",
      "kid": "eXaunmL",
      "use": "sig",
      "alg": "RS256",
      "n": "4dGQ7bQK8LgILOdLsYzfZjkEAoQeVC_aqyc8GC6RX7dq_KvRAQAWPvkam8VQv4GK5T4ogklEKEvj5ISBamdDNq1n52TpxQwI2EqxSk7I9fKPKhRt4F8-2yETlYvye-2s6NeWJim0KBtOVrk0gWvEDgd6WOqJl_yt5WBISvILNyVg1qAAM8JeX6dRPosahRVDjA52G2X-Tip84wqwyRpUlq2ybzcLh3zyhCitBOebiRWDQfG26EH9lTlJhll-p_Dg8vAXxJLIJ4SNLcqgFeZe4OfHLgdzMvxXZJnPp_VgmkcpUdRotazKZumj6dBPcXI_XID4Z4Z3OM1KrZPJNdUhxw",
      "e": "AQAB"
    },
    {
      "kty": "RSA",
      "kid": "AIDOPK1",
      "use": "sig",
      "alg": "RS256",
      "n": "lxrwmuYSAsTfn-lUu4goZSXBD9ackM9OJuwUVQHmbZo6GW4Fu_auUdN5zI7Y1dEDfgt7m7QXWbHuMD01HLnD4eRtY-RNwCWdjNfEaY_esUPY3OVMrNDI15Ns13xspWS3q-13kdGv9jHI28P87RvMpjz_JCpQ5IM44oSyRnYtVJO-320SB8E2Bw92pmrenbp67KRUzTEVfGU4-obP5RZ09OxvCr1io4KJvEOjDJuuoClF66AT72WymtoMdwzUmhINjR0XSqK6H0MdWsjw7ysyd_JhmqX5CAaT9Pgi0J8lU_pcl215oANqjy7Ob-VMhug9eGyxAWVfu_1u6QJKePlE-w",
      "e": "AQAB"
    }
  ]
}

The current implementation (commit 4620926) of the token verification only fetches the first key, sent by Apple

const key = data.keys[0];

Thus failing verification every time a token with a different kid than the first one is returned.

Steps to reproduce

1. Grab an id token from Sign in with Apple

2. Verify that its kid is different from the first element of the array that apple returns from this API - Apple API

3. Use the current Parse Server version to verify it code

Expected Results

The token should be verified, regardless of the provided kid

Actual Outcome

The token verification fails, even though the token is valid

Environment Setup

• Server
  • parse-server version: 3.10.0
  • Operating System: macOS

Logs/Trace

[parse-github-assistant]

The label type:feature cannot be used in combination with type:improvement.