title: What's the best encryption algorithm for the iPhone in terms of speed and security?
body: <p>The iPhone supports the following encryption algorithms</p>
  
  <pre><code>enum {
      kCCAlgorithmAES128 = 0,
      kCCAlgorithmDES,            
      kCCAlgorithm3DES,           
      kCCAlgorithmCAST,           
      kCCAlgorithmRC4,
      kCCAlgorithmRC2 
  };
  </code></pre>
  
  <p>I want to use only symmetric algorithm since asymmetric encryptions requires more computation overhead.</p>
  
  <p>So I want to know which of the ones listed is the best algorithm and also what is the key-length in order to avoid excessive computation overhead.</p>