title: Validating access token with at_hash
body: <p>I'm trying to validate access tokens against at_hash. Token header is like this</p>
  
  <p><code>{
    "typ": "JWT",
    "alg": "RS256",
    "x5t": "MclQ7Vmu-1e5_rvdSfBShLe82eY",
    "kid": "MclQ7Vmu-1e5_rvdSfBShLe82eY"
  }</code></p>
  
  <p>How do I get from my access token to the Base64 encoded at_hash claim value that is in the id token? Is there an online tool that could help me with this? Is SHA256 hash calculator not a correct tool for this?</p>
  
  <p>Thanks</p>