title: How can I decrypt a HMAC?
body: <p>I can make an HMAC using the following:</p>
  
  <pre><code>var encrypt = crypto.createHmac("SHA256", secret).update(string).digest('base64');
  </code></pre>
  
  <p>I am trying to decrypt an encoded HMAC with the secret:</p>
  
  <pre><code>var decrypt = crypto.createDecipher("SHA256", secret).update(string).final("ascii");
  </code></pre>
  
  <p>The following was unsuccessful. How can I decrypt a HMAC with the key?</p>
  
  <p>I get the following error:</p>
  
  <pre><code>node-crypto : Unknown cipher SHA256
  
  crypto.js:155
    return (new Decipher).init(cipher, password);
                          ^
  Error: DecipherInit error
  </code></pre>