WAEncrypt method for PHP

function WAEncrypt($src, $key){
  $pkey = $key;
  while (strlen($pkey)<16)
    $pkey .= '0';
  $chars = 'abdefhiknrstyzABDEFGHKNQRSTYZ23456789';
  $numChars = strlen($chars);
  $iv = '';
  for ($i = 0; $i < 16; $i++) {
    $iv .= substr($chars, rand(1, $numChars) - 1, 1);
  }
  $block = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, 'cbc');
  $pad = $block - (strlen($src) % $block);
  $src .= str_repeat(chr($pad), $pad);  
  $enc = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $pkey, $src, MCRYPT_MODE_CBC, $iv);
  return $iv.'|'.base64_encode($enc);
}