Encryption and Decrytion for PHP

EncryptDecrypt.php

<?php
/**
 * Encrypts a string using Rijndael with a 256-bit (32 character) salt.
 *
 * @param string $text The text to encrypt.
 * @param string $key The encryption key to use.
 * @param string $iv The optional initialization vector to use.
 *
 * @return string Base64 encoded encrypted text.
 */
public function encrypt($text, $key, $iv = NULL) {
	assert(TRUE === is_string(base64_encode($text)));
	assert(TRUE === is_string(base64_encode($key)));
	assert(TRUE === is_null($iv) || TRUE === is_string(base64_encode($iv)));
	$return = $text;
	if (FALSE === isset($iv)) {
		$iv = mhash(MHASH_SHA256, $key);
	}
	$cipher = mcrypt_module_open(MCRYPT_RIJNDAEL_256, '', MCRYPT_MODE_CBC, '');
	$key = substr(pad($key, mcrypt_enc_get_key_size($cipher)), 0, mcrypt_enc_get_key_size($cipher));
	$iv = substr(pad($iv, mcrypt_enc_get_iv_size($cipher)), 0, mcrypt_enc_get_iv_size($cipher));
	if (mcrypt_generic_init($cipher, $key, $iv) !== -1) {
		$return = mcrypt_generic($cipher, $text);
		mcrypt_generic_deinit($cipher);
		$return = base64_encode($return);
	}
	return $return;
}

/**
 * Decrypts a Base64 encoded string that was encrypted by "encrypt".
 *
 * @param string $text The Base64 text to decrypt.
 * @param string $key The encryption key to use.
 * @param string $iv The initialization vector to use.
 *
 * @return string Decrypted text or binary string.
 */
public function decrypt($text, $key, $iv = NULL) {
	assert(TRUE === is_string($text));
	assert(TRUE === is_string(base64_encode($key)));
	assert(TRUE === is_NULL($iv) || TRUE === is_string(base64_encode($iv)));
	$return = $text;
	if (FALSE === isset($iv)) {
		$iv = mhash(MHASH_SHA256, $key);
	}
	$text = base64_decode($text);
	$cipher = mcrypt_module_open(MCRYPT_RIJNDAEL_256, '', MCRYPT_MODE_CBC, '');
	$key = substr(pad($key, mcrypt_enc_get_key_size($cipher)), 0, mcrypt_enc_get_key_size($cipher));
	$iv = substr(pad($iv, mcrypt_enc_get_iv_size($cipher)), 0, mcrypt_enc_get_iv_size($cipher));
	if (mcrypt_generic_init($cipher, $key, $iv) !== -1) {
		$return = mdecrypt_generic($cipher, $text);
		mcrypt_generic_deinit($cipher);
	}
	return trim($return);
}

/**
 * Pads or trims a string to the specified number of characters.
 *
 * @param string $text String or binary string to pad.
 * @param int $length The number of characters to return.
 * @param string $char Optionally, the character used to pad the string.
 *
 * @return string The padded or trimmed string.
 */
private function pad($text, $length, $char = ' ') {
	assert(TRUE === is_string(base64_encode($text)));
	assert(TRUE === is_int($length));
	assert(TRUE === is_string($char));
	$return = $text;
	if (mb_strlen($text) < $length) {
		$return = mb_str_pad($text, $length, $char);
	}
	if (mb_strlen($text) > $length) {
		$return = mb_substr($text, 0, $length);
	}
	return $return;
}