title: PHP AES 128 bit CBC Encryption gives a size warning
body: <p>i am using the AES ALgo with 128 bit  with CBC cipher mode encryption, below is the code:</p>
  
  <pre><code>$cc = 'my secret text';
  $key = '3aa22e01c04c7059778c54d122b0273689fba00f4a166a66d15f7ba6a8ba8743';
  $iv =  '1234567890123456';
  $length = strlen($cc);
  
  $cipher = mcrypt_module_open(MCRYPT_RIJNDAEL_128,'','cbc','');
  
  mcrypt_generic_init($cipher, $key, $iv);
  $encrypted = base64_encode(mcrypt_generic($cipher,$cc));
  mcrypt_generic_deinit($cipher);
  
  mcrypt_generic_init($cipher, $key, $iv);
  $decrypted = mdecrypt_generic($cipher,base64_decode($encrypted));
  mcrypt_generic_deinit($cipher);
  
  echo "encrypted: " . $encrypted;
  echo "\n";
  echo "decrypted: " . substr($decrypted, 0, $length) . "\n";
  </code></pre>
  
  <p>But this gives me a warning with output as :</p>
  
  <blockquote>
    <p>Warning: mcrypt_generic_init(): Key size too large; supplied length:
    64, max: 32 in /var/www/cipher.php on line 10 Warning:
    mcrypt_generic_init(): Key size too large; supplied length: 64, max:
    32 in /var/www/cipher.php on line 14 encrypted:
    vM/XVYSjs/QApdCUEQ8bdQ== decrypted: my secret text</p>
  </blockquote>
  
  <p>Now can someone guide me on why I am facing the size issue and how I can eradicate the issue of size without changing the key...</p>