title: CBC-MAC decryption, how MAC works in encryption
body: <p>I just figured out Triple DES encryption and decryption for credit card. Can any one tell me how to de-crypt CBC-MAC...CBC-MAC at the end would give a 4 byte MAC. From MAC to Encryption, how exactly does it work? What is MAC doing? </p>
  
  <p>Once there is an encryption done through CBC-MAC, how can we de-crypt them? Triple-DES would not work for my case.</p>
  
  <p><strong>Another question here</strong>. have you all heard of any decryption algorithm that involves:</p>
  
  <ul>
  <li>DUKPT</li>
  <li>TDES, and</li>
  <li>MAC variant (versus PIN variant)</li>
  </ul>
  
  <p>I have good understanding of TDES and DUKPT, but how  would MAC variant play a role in the decryption algorithm? </p>
  
  <p>How is MAC variant different from PIN variant? </p>
  
  <p>Thank you!</p>