title: For AES128 using CCCrypt() can the key be longer than 128 bits?
body: <p>I am using the <a href="https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/CCCrypt.3cc.html" rel="nofollow noreferrer"><code>CCCrypt</code></a> method.</p>
  
  <p>Can I use a longer key than than 128bit? Can it be arbitrarily long? Or perhaps multiples of 128?</p>
  
  <p>If so how would I do this?</p>
  
  <p>I didn't think this woas possible but I found this text: <a href="http://download.oracle.com/javase/6/docs/technotes/guides/security/crypto/CryptoSpec.html" rel="nofollow noreferrer">here</a></p>
  
  <blockquote>
    <p><strong>Some algorithms such as AES and RSA allow for keys of different lengths</strong>, but others are fixed, such as DES and 3DES. Encryption using a longer key generally implies a stronger resistance to message recovery. As usual, there is a trade off between security and time, so choose the key length appropriately.</p>
  </blockquote>
  
  <p>How does AES allow for different lengths, does it ignore the bits higher than 128?</p>
  
  <p>I'm pulling my hair out over this.</p>