我想制作一个应该有一些密钥的加密函数。类似于以下内容：
function encrypt($string) {
$key = "mastermind";
$enc = encryptfunc($string, $key);
return $enc;
}
同样的事情应该适用于解密。
【问题讨论】：
标签： php encryption
这里是AES-256 CBC 模式下简单但安全的加密实现，它使用 PBKDF2 从纯文本密码创建加密密钥，并使用 HMAC 对加密消息进行身份验证。
它适用于 PHP 5.3 及更高版本。
/**
* Implements AES-256 encryption/decryption in CBC mode.
*
* PBKDF2 is used for creation of encryption key.
* HMAC is used to authenticate the encrypted message.
*
* Requires PHP 5.3 and higher
*
* Gist: https://gist.github.com/eugef/3d44b2e0a8a891432c65
*/
class McryptCipher
{
const PBKDF2_HASH_ALGORITHM = 'SHA256';
const PBKDF2_ITERATIONS = 64000;
const PBKDF2_SALT_BYTE_SIZE = 32;
// 32 is the maximum supported key size for the MCRYPT_RIJNDAEL_128
const PBKDF2_HASH_BYTE_SIZE = 32;
/**
* @var string
*/
private $password;
/**
* @var string
*/
private $secureEncryptionKey;
/**
* @var string
*/
private $secureHMACKey;
/**
* @var string
*/
private $pbkdf2Salt;
public function __construct($password)
{
$this->password = $password;
}
/**
* Compares two strings.
*
* This method implements a constant-time algorithm to compare strings.
* Regardless of the used implementation, it will leak length information.
*
* @param string $knownHash The string of known length to compare against
* @param string $userHash The string that the user can control
*
* @return bool true if the two strings are the same, false otherwise
*
* @see https://github.com/symfony/security-core/blob/master/Util/StringUtils.php
*/
private function equalHashes($knownHash, $userHash)
{
if (function_exists('hash_equals')) {
return hash_equals($knownHash, $userHash);
}
$knownLen = strlen($knownHash);
$userLen = strlen($userHash);
if ($userLen !== $knownLen) {
return false;
}
$result = 0;
for ($i = 0; $i < $knownLen; $i++) {
$result |= (ord($knownHash[$i]) ^ ord($userHash[$i]));
}
// They are only identical strings if $result is exactly 0...
return 0 === $result;
}
/**
* PBKDF2 key derivation function as defined by RSA's PKCS #5: https://www.ietf.org/rfc/rfc2898.txt
*
* Test vectors can be found here: https://www.ietf.org/rfc/rfc6070.txt
* This implementation of PBKDF2 was originally created by https://defuse.ca
* With improvements by http://www.variations-of-shadow.com
*
* @param string $algorithm The hash algorithm to use. Recommended: SHA256
* @param string $password The password
* @param string $salt A salt that is unique to the password
* @param int $count Iteration count. Higher is better, but slower. Recommended: At least 1000
* @param int $key_length The length of the derived key in bytes
* @param bool $raw_output If true, the key is returned in raw binary format. Hex encoded otherwise
* @return string A $key_length-byte key derived from the password and salt
*
* @see https://defuse.ca/php-pbkdf2.htm
*/
private function pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false)
{
$algorithm = strtolower($algorithm);
if (!in_array($algorithm, hash_algos(), true)) {
trigger_error('PBKDF2 ERROR: Invalid hash algorithm.', E_USER_ERROR);
}
if ($count <= 0 || $key_length <= 0) {
trigger_error('PBKDF2 ERROR: Invalid parameters.', E_USER_ERROR);
}
if (function_exists('hash_pbkdf2')) {
// The output length is in NIBBLES (4-bits) if $raw_output is false!
if (!$raw_output) {
$key_length *= 2;
}
return hash_pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output);
}
$hash_length = strlen(hash($algorithm, '', true));
$block_count = ceil($key_length / $hash_length);
$output = '';
for ($i = 1; $i <= $block_count; $i++) {
// $i encoded as 4 bytes, big endian.
$last = $salt . pack('N', $i);
// first iteration
$last = $xorsum = hash_hmac($algorithm, $last, $password, true);
// perform the other $count - 1 iterations
for ($j = 1; $j < $count; $j++) {
$xorsum ^= ($last = hash_hmac($algorithm, $last, $password, true));
}
$output .= $xorsum;
}
if ($raw_output) {
return substr($output, 0, $key_length);
} else {
return bin2hex(substr($output, 0, $key_length));
}
}
/**
* Creates secure PBKDF2 derivatives out of the password.
*
* @param null $pbkdf2Salt
*/
private function derivateSecureKeys($pbkdf2Salt = null)
{
if ($pbkdf2Salt) {
$this->pbkdf2Salt = $pbkdf2Salt;
}
else {
$this->pbkdf2Salt = mcrypt_create_iv(self::PBKDF2_SALT_BYTE_SIZE, MCRYPT_DEV_URANDOM);
}
list($this->secureEncryptionKey, $this->secureHMACKey) = str_split(
$this->pbkdf2(self::PBKDF2_HASH_ALGORITHM, $this->password, $this->pbkdf2Salt, self::PBKDF2_ITERATIONS, self::PBKDF2_HASH_BYTE_SIZE * 2, true),
self::PBKDF2_HASH_BYTE_SIZE
);
}
/**
* Calculates HMAC for the message.
*
* @param string $message
* @return string
*/
private function hmac($message)
{
return hash_hmac(self::PBKDF2_HASH_ALGORITHM, $message, $this->secureHMACKey, true);
}
/**
* Encrypts the input text
*
* @param string $input
* @return string Format: hmac:pbkdf2Salt:iv:encryptedText
*/
public function encrypt($input)
{
$this->derivateSecureKeys();
$mcryptIvSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
// By default mcrypt_create_iv() function uses /dev/random as a source of random values.
// If server has low entropy this source could be very slow.
// That is why here /dev/urandom is used.
$iv = mcrypt_create_iv($mcryptIvSize, MCRYPT_DEV_URANDOM);
$encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $this->secureEncryptionKey, $input, MCRYPT_MODE_CBC, $iv);
$hmac = $this->hmac($this->pbkdf2Salt . $iv . $encrypted);
return implode(':', array(
base64_encode($hmac),
base64_encode($this->pbkdf2Salt),
base64_encode($iv),
base64_encode($encrypted)
));
}
/**
* Decrypts the input text.
*
* @param string $input Format: hmac:pbkdf2Salt:iv:encryptedText
* @return string
*/
public function decrypt($input)
{
list($hmac, $pbkdf2Salt, $iv, $encrypted) = explode(':', $input);
$hmac = base64_decode($hmac);
$pbkdf2Salt = base64_decode($pbkdf2Salt);
$iv = base64_decode($iv);
$encrypted = base64_decode($encrypted);
$this->derivateSecureKeys($pbkdf2Salt);
$calculatedHmac = $this->hmac($pbkdf2Salt . $iv . $encrypted);
if (!$this->equalHashes($calculatedHmac, $hmac)) {
trigger_error('HMAC ERROR: Invalid HMAC.', E_USER_ERROR);
}
// mcrypt_decrypt() pads the *RETURN STRING* with nulls ('\0') to fill out to n * blocksize.
// rtrim() is used to delete them.
return rtrim(
mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $this->secureEncryptionKey, $encrypted, MCRYPT_MODE_CBC, $iv),
"\0"
);
}
}
用法：
$c = new McryptCipher('secret key goes here');
$encrypted = $c->encrypt('secret message');
$decrypted = $c->decrypt($encrypted);
关于性能的通知
默认情况下，mcrypt_create_iv() 函数使用 /dev/random 作为随机值的来源。如果服务器具有低熵，则此源可能非常慢。这就是使用 /dev/urandom 的原因。
这里很好地解释了它们之间的区别http://www.onkarjoshi.com/blog/191/device-dev-random-vs-urandom/
因此，如果您不将这种加密用于关键的事情（我希望您不这样做），那么您可以使用 /dev/urandom 来提高加密性能，否则只需将 MCRYPT_DEV_URANDOM 替换为 MCRYPT_DEV_RANDOM。
重要的安全更新 #1
感谢@HerrK，他指出使用简单的哈希来创建加密密钥不够安全 - 现在使用 PBKDF2 算法（阅读有关 PBKDF2 的更多信息http://en.wikipedia.org/wiki/PBKDF2）。
PBKDF2算法的实现抄自https://defuse.ca/php-pbkdf2.htm。
重要的安全更新 #2
感谢@Scott 注意到加密消息应该经过身份验证 - 现在使用 HMAC 来验证消息没有被更改。
【讨论】：
安全警告：Encryption without authentication 容易受到称为选择密文攻击的攻击。请参阅 Eugene's answer 了解提供经过身份验证的加密的解决方案。
如果您使用的是 PHP >= 5.3，新的 openssl_encrypt 可能会对您有所帮助：它允许使用多种密码方法对数据进行加密。
这些数据稍后可以使用openssl_decrypt 解密，显然，这恰恰相反。
如果您想知道可以使用哪些密码函数，openssl_get_cipher_methods 会很有帮助；-)
好像还挺多的吧^^
这是我前段时间在我的博客上发布的部分代码，应该可以演示这三个函数的用法：
$methods = openssl_get_cipher_methods();
var_dump($methods);
$textToEncrypt = "he who doesn't do anything, doesn't go wrong -- Zeev Suraski";
$secretKey = "glop";
echo '<pre>';
foreach ($methods as $method) {
$encrypted = openssl_encrypt($textToEncrypt, $method, $secretKey);
$decrypted = openssl_decrypt($encrypted, $method, $secretKey);
echo $method . ': ' . $encrypted . ' ; ' . $decrypted . "\n";
}
echo '</pre>';
我写这篇文章时得到的输出是这样的：
bf-ecb: /nyRYCzQPE1sunxSBclxXBd7p7gl1fUnE80gBCS1NM4s3wS1Eho6rFHOOR73V9UtnolYW+flbiCwIKa/DYh5CQ== ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
bf-ofb: M9wwf140zhwHo98k8sj2MEXdogqXEQ+TjN81pebs2tmhNOsfU3jvMy91MBM76dWM7GVjeh95p8oDybDt ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
cast5-cbc: xKgdC1y654PFYW1rIjdevu8MsQOegvJoZx0KmMwb8aCHFmznxIQVy1yvAWR3bZztvGCGrM84WkpbG33pZcxUiQ== ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
cast5-cfb: t8ABR9mPvocRikrX0Kblq2rUXHiVnA/OnjR/mDJDq8+/nn6Z9yfPbpcpRat0lYqfVAcwlypT4A4KNq4S ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
cast5-ecb: xKgdC1y654NIzRl9gJqbhYKtmJoXBoFpgLhwgdtPtYB7VZ1tRHLX0MjErtfREMJBAonp48zngSiTKlsKV0/WhQ== ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
cast5-ofb: t8ABR9mPvofCv9+AKTcRO4Q0doYlavn8zRzLvV3dZk0niO7l20KloA4nUll4VN1B5n89T/IuGh9piPte ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
des-cbc: WrCiOVPU1ipF+0trwXyVZ/6cxiNVft+TK2+vAP0E57b9smf9x/cZlQQ4531aDX778S3YJeP/5/YulADXoHT/+Q== ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
des-cfb: cDDlaifQN+hGOnGJ2xvGna7y8+qRxwQG+1DJBwQm/4abKgdZYUczC4+aOPGesZM1nKXjgoqB4+KTxGNo ; he who doesn't do anything, doesn't go wrong -- Zeev Suraski
如果您不使用 PHP 5.3，您可能需要查看手册的 Mcrypt 部分，以及 mcrypt_encrypt 等函数；-)
这是 mcrypt 的接口 库，它支持各种各样的 块算法，例如 DES， TripleDES、Blowfish（默认）、3-WAY、 SAFER-SK64, SAFER-SK128, TWOFISH, TEA, CBC、OFB、CFB 和 ECB 中的 RC2 和 GOST 密码模式。
【讨论】：
我不是加密人，但我使用这种东西：
function crypt($dataToEncrypt){
$appKey = '%39d15#13P0£df458asdc%/dfr_A!8792*dskjfzaesdfpopdfo45s4dqd8d4fsd+dfd4s"Z1';
$td = mcrypt_module_open(MCRYPT_SERPENT, '', MCRYPT_MODE_CBC, '');
// Creates IV and gets key size
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);
$ks = mcrypt_enc_get_key_size($td);
// Creates key from application key
$key = substr($appKey, 0, $ks);
// Initialization
mcrypt_generic_init($td, $key, $iv);
// Crypt data
$encrypted = mcrypt_generic($td, $dataToEncrypt);
// Close
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return array($encrypted, $iv);
}
要解密字符串，您需要密钥和初始化向量 ($iv)。
function decrypt($encryptedData, $iv){
$appKey = '%39d15#13P0£df458asdc%/dfr_A!8792*dskjfzaesdfpopdfo45s4dqd8d4fsd+dfd4s"Z1';
$td = mcrypt_module_open(MCRYPT_SERPENT, '', MCRYPT_MODE_CBC, '');
// Gets key size
$ks = mcrypt_enc_get_key_size($td);
// Creates key from application key
$key = substr($appKey, 0, $ks);
// Initialization
mcrypt_generic_init($td, $key, $iv);
// Decrypt data
$decrypted = mdecrypt_generic($td, $encryptedData);
// Close
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return trim($decrypted);
}
【讨论】：
这是 Eugene Fidelin 原始代码的更新和安全版本。
请注意输出中包含 IV 和 Salt，您还需要使用解密密钥安全地存储它们。
class Cipher
{
/**
----------------------------------------------
Original Code by Eugene Fidelin
----------------------------------------------
**/
private $key;
private $salt;
private $iv;
function __construct()
{
}
function set_salt( $salt )
{
$this->salt = $salt;
}
function generate_salt()
{
$this->salt = mcrypt_create_iv( 32, MCRYPT_DEV_RANDOM ); // abuse IV function for random salt
}
function set_iv( $iv )
{
$this->iv = $iv;
}
function generate_iv()
{
$this->iv = mcrypt_create_iv( mcrypt_get_iv_size( MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC ) );
}
function generate_key( $passphrase, $iterations = 10000, $length = 32 )
{
$this->key = hash_pbkdf2 ( 'sha256', $passphrase, $this->salt, $iterations, $length );
}
function get_key()
{
echo $this->key;
}
function encrypt( $plaintext )
{
$ciphertext = mcrypt_encrypt( MCRYPT_RIJNDAEL_128, $this->key, $plaintext, MCRYPT_MODE_CBC, $this->iv );
$data_return = array();
$data_return['iv'] = base64_encode( $this->iv );
$data_return['salt'] = base64_encode( $this->salt );
$data_return['ciphertext'] = base64_encode( $ciphertext );
return json_encode( $data_return );
}
function decrypt( $data_enciphered, $passphrase )
{
$data_decoded = json_decode( $data_enciphered, TRUE );
$this->set_iv( base64_decode( $data_decoded['iv'] ) );
$this->set_salt( base64_decode( $data_decoded['salt'] ) );
$this->generate_key( $passphrase );
$ciphertext = base64_decode( $data_decoded['ciphertext'] );
return trim( mcrypt_decrypt( MCRYPT_RIJNDAEL_128, $this->key, $ciphertext, MCRYPT_MODE_CBC, $this->iv ) );
}
}
$cipher = new Cipher();
$cipher->generate_salt();
$cipher->generate_iv();
$cipher->generate_key( '123' ); // the key will be generated from the passphrase "123"
// echo $cipher->get_key();
$data_encrypted = $cipher->encrypt( 'hello' );
echo 'encrypted:';
echo '<pre>';
print_r( $data_encrypted );
echo '</pre>';
unset( $cipher );
echo 'decrypted:';
$cipher = new Cipher();
$decrypted = $cipher->decrypt( $data_encrypted, '123' );
echo '<pre>';
print_r( $decrypted );
echo '</pre>';
die();
【讨论】：
这是一个很好的 PHP 库，可以帮助您加密和解密字符串 - 可通过 Composer 获得并且也易于使用：
https://github.com/CoreProc/crypto-guard
这是一个示例：
<?php
require 'vendor/autoload.php';
use Coreproc\CryptoGuard\CryptoGuard;
// This passphrase should be consistent and will be used as your key to encrypt/decrypt
// your string
$passphrase = 'whatever-you-want';
// Instantiate the CryptoGuard class
$cryptoGuard = new CryptoGuard($passphrase);
$stringToEncrypt = 'test';
// This will spit out the encrypted text
$encryptedText = $cryptoGuard->encrypt($stringToEncrypt);
// This should give you back the string you encrypted
echo $cryptoGuard->decrypt($encryptedText);
【讨论】：