首先,要对你需要即兴创作的输入做PKCS#5填充：

// source: http://php.net/manual/en/ref.mcrypt.php#69782

function pkcs5_pad($text, $blocksize)

{

$pad = $blocksize - (strlen($text) % $blocksize);

return $text . str_repeat(chr($pad), $pad);

}

然后选择你的算法并生成IV：

$alg = MCRYPT_RIJNDAEL_128; // AES

$mode = MCRYPT_MODE_ECB; // not recommended unless used with OTP

$iv_size = mcrypt_get_iv_size($alg, $mode);

$block_size = mcrypt_get_block_size($alg, $mode);

$iv = mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM); // pull from /dev/urandom

初始化加密密钥：

$key = "This is a very secret key";

将填充应用于输入并加密

$input = pkcs5_pad($input, $block_size);

$crypttext = mcrypt_encrypt($alg, $key, $input, $mode, $iv);