title: Verify key is correct using pyCrypto AES decryption
body: <p>How do I verify the correct key is being used to decrypt AES encrypted data using pyCrypto AES?</p>
  
  <pre><code>cipher = AES.new(key, AES.MODE_CFB)
  cipher.decrypt(s)
  </code></pre>
  
  <p>If an incorrect key is used, it still attempts to decrypt the data, obfuscating it more. Is there any test I can do to prove the data is being decrypted to the original state?</p>