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yii2/framework/base/Security.php

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<?php
/**
* @link http://www.yiiframework.com/
* @copyright Copyright (c) 2008 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
namespace yii\base;
use yii\helpers\StringHelper;
use Yii;
/**
* Security provides a set of methods to handle common security-related tasks.
*
* In particular, Security supports the following features:
*
* - Encryption/decryption: [[encrypt()]] and [[decrypt()]]
* - Data tampering prevention: [[hashData()]] and [[validateData()]]
* - Password validation: [[generatePasswordHash()]] and [[validatePassword()]]
*
* Additionally, Security provides [[getSecretKey()]] to support generating
* named secret keys. These secret keys, once generated, will be stored in a file
* and made available in future requests.
*
* This component provides several configuration parameters, which allow tuning your own balance
* between high security and high performance.
*
* > Tip: you may add several `Security` components with different configurations to your application,
* this allows usage of different encryption strategies for different use cases or migrate encrypted data
* from outdated strategy to the new one.
*
* > Note: this class requires 'mcrypt' PHP extension. For the highest security level PHP version >= 5.5.0 is recommended.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @author Tom Worster <fsb@thefsb.org>
* @author Klimov Paul <klimov.paul@gmail.com>
* @since 2.0
*/
class Security extends Component
{
/**
* @var integer crypt block size in bytes.
* For AES-128, AES-192, block size is 128-bit (16 bytes).
* For AES-256, block size is 256-bit (32 bytes).
* Recommended value: 32
*/
public $cryptBlockSize = 32;
/**
* @var integer crypt key size in bytes.
* For AES-192, key size is 192-bit (24 bytes).
* For AES-256, key size is 256-bit (32 bytes).
* Recommended value: 32
*/
public $cryptKeySize = 32;
/**
* @var string derivation hash algorithm name.
* Recommended value: 'sha256'
*/
public $derivationHash = 'sha256';
/**
* @var integer derivation iterations count.
* Recommended value: 1000000
*/
public $derivationIterations = 1000000;
/**
* @var string strategy, which should be used to derive a key for encryption.
* Available strategies:
* - 'pbkdf2' - PBKDF2 key derivation. This option is recommended, but it requires PHP version >= 5.5.0
* - 'hmac' - HMAC hash key derivation.
*/
public $deriveKeyStrategy = 'hmac';
/**
* @var string strategy, which should be used to generate password hash.
* Available strategies:
* - 'password_hash' - use of PHP `password_hash()` function with PASSWORD_DEFAULT algorithm. This option is recommended,
* but it requires PHP version >= 5.5.0
* - 'crypt' - use PHP `crypt()` function.
*/
public $passwordHashStrategy = 'crypt';
/**
* @var boolean whether to generate unique salt while deriving encryption key.
* If enabled (recommended) this option increases encrypted text length, but provide more security.
* If disabled this option reduces encrypted text length, but also reduces security.
*/
public $useDeriveKeyUniqueSalt = true;
/**
* @var string the path or alias of a file that stores the secret keys automatically generated by [[getSecretKey()]].
* The file must be writable by Web server process. It contains a JSON hash of key names and key values.
*/
public $secretKeyFile = '@runtime/keys.json';
/**
* Encrypts data.
* @param string $data data to be encrypted.
* @param string $password the encryption password
* @return string the encrypted data
* @throws Exception if PHP Mcrypt extension is not loaded or failed to be initialized
* @see decrypt()
*/
public function encrypt($data, $password)
{
$module = $this->openCryptModule();
$data = $this->addPadding($data);
$ivSize = mcrypt_enc_get_iv_size($module);
$iv = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM);
if ($this->useDeriveKeyUniqueSalt) {
$keySalt = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM);
$encrypted = $keySalt;
} else {
$keySalt = $iv;
$encrypted = '';
}
$key = $this->deriveKey($password, $keySalt);
mcrypt_generic_init($module, $key, $iv);
$encrypted .= $iv . mcrypt_generic($module, $data);
mcrypt_generic_deinit($module);
mcrypt_module_close($module);
return $encrypted;
}
/**
* Decrypts data
* @param string $data data to be decrypted.
* @param string $password the decryption password
* @return string the decrypted data
* @throws Exception if PHP Mcrypt extension is not loaded or failed to be initialized
* @see encrypt()
*/
public function decrypt($data, $password)
{
if ($data === null) {
return null;
}
$module = $this->openCryptModule();
$ivSize = mcrypt_enc_get_iv_size($module);
$iv = StringHelper::byteSubstr($data, 0, $ivSize);
$keySalt = $iv;
$encrypted = StringHelper::byteSubstr($data, $ivSize, StringHelper::byteLength($data));
if ($this->useDeriveKeyUniqueSalt) {
$iv = StringHelper::byteSubstr($encrypted, 0, $ivSize);
$encrypted = StringHelper::byteSubstr($encrypted, $ivSize, StringHelper::byteLength($encrypted));
}
$key = $this->deriveKey($password, $keySalt);
mcrypt_generic_init($module, $key, $iv);
$decrypted = mdecrypt_generic($module, $encrypted);
mcrypt_generic_deinit($module);
mcrypt_module_close($module);
return $this->stripPadding($decrypted);
}
/**
* Adds a padding to the given data (PKCS #7).
* @param string $data the data to pad
* @return string the padded data
*/
protected function addPadding($data)
{
$pad = $this->cryptBlockSize - (StringHelper::byteLength($data) % $this->cryptBlockSize);
return $data . str_repeat(chr($pad), $pad);
}
/**
* Strips the padding from the given data.
* @param string $data the data to trim
* @return string the trimmed data
*/
protected function stripPadding($data)
{
$end = StringHelper::byteSubstr($data, -1, null);
$last = ord($end);
$n = StringHelper::byteLength($data) - $last;
if (StringHelper::byteSubstr($data, $n, null) === str_repeat($end, $last)) {
return StringHelper::byteSubstr($data, 0, $n);
}
return false;
}
/**
* Derives a key from the given password (PBKDF2).
* @param string $password the source password
* @param string $salt the random salt
* @throws InvalidConfigException if unsupported derive key strategy is configured.
* @return string the derived key
*/
protected function deriveKey($password, $salt)
{
switch ($this->deriveKeyStrategy) {
case 'pbkdf2':
return $this->deriveKeyPbkdf2($password, $salt);
case 'hmac':
return $this->deriveKeyHmac($password, $salt);
default:
throw new InvalidConfigException("Unknown derive key strategy '{$this->deriveKeyStrategy}'");
}
}
/**
* Derives a key from the given password using PBKDF2.
* @param string $password the source password
* @param string $salt the random salt
* @throws InvalidConfigException if environment does not allows PBKDF2.
* @return string the derived key
*/
protected function deriveKeyPbkdf2($password, $salt)
{
if (function_exists('hash_pbkdf2')) {
return hash_pbkdf2($this->derivationHash, $password, $salt, $this->derivationIterations, $this->cryptKeySize, true);
} else {
throw new InvalidConfigException('Security::$deriveKeyStrategy is set to "pbkdf2", which requires PHP >= 5.5.0. Either upgrade your run-time environment or use another strategy.');
}
}
/**
* Derives a key from the given password using HMAC.
* @param string $password the source password
* @param string $salt the random salt
* @return string the derived key
*/
protected function deriveKeyHmac($password, $salt)
{
$hmac = hash_hmac($this->derivationHash, $salt . pack('N', 1), $password, true);
$xorsum = $hmac;
for ($i = 1; $i < $this->derivationIterations; $i++) {
$hmac = hash_hmac($this->derivationHash, $hmac, $password, true);
$xorsum ^= $hmac;
}
return substr($xorsum, 0, $this->cryptKeySize);
}
/**
* Prefixes data with a keyed hash value so that it can later be detected if it is tampered.
* @param string $data the data to be protected
* @param string $key the secret key to be used for generating hash
* @param string $algorithm the hashing algorithm (e.g. "md5", "sha1", "sha256", etc.). Call PHP "hash_algos()"
* function to see the supported hashing algorithms on your system.
* @return string the data prefixed with the keyed hash
* @see validateData()
* @see getSecretKey()
*/
public function hashData($data, $key, $algorithm = 'sha256')
{
return hash_hmac($algorithm, $data, $key) . $data;
}
/**
* Validates if the given data is tampered.
* @param string $data the data to be validated. The data must be previously
* generated by [[hashData()]].
* @param string $key the secret key that was previously used to generate the hash for the data in [[hashData()]].
* @param string $algorithm the hashing algorithm (e.g. "md5", "sha1", "sha256", etc.). Call PHP "hash_algos()"
* function to see the supported hashing algorithms on your system. This must be the same
* as the value passed to [[hashData()]] when generating the hash for the data.
* @return string the real data with the hash stripped off. False if the data is tampered.
* @see hashData()
*/
public function validateData($data, $key, $algorithm = 'sha256')
{
$hashSize = StringHelper::byteLength(hash_hmac($algorithm, 'test', $key));
$n = StringHelper::byteLength($data);
if ($n >= $hashSize) {
$hash = StringHelper::byteSubstr($data, 0, $hashSize);
$pureData = StringHelper::byteSubstr($data, $hashSize, $n - $hashSize);
$calculatedHash = hash_hmac($algorithm, $pureData, $key);
if ($this->compareString($hash, $calculatedHash)) {
return $pureData;
} else {
return false;
}
} else {
return false;
}
}
private $_keys;
/**
* Returns a secret key associated with the specified name.
* If the secret key does not exist, it will be automatically generated and saved in [[secretKeyFile]].
* @param string $name the name that is associated with the secret key
* @param integer $length the length of the key that should be generated if not exists
* @param boolean $regenerate whether to regenerate a secret if it already exists
* @return string the secret key associated with the specified name
*/
public function getSecretKey($name, $length = 32, $regenerate = false)
{
$keyFile = Yii::getAlias($this->secretKeyFile);
if ($this->_keys === null) {
$this->_keys = is_file($keyFile) ? json_decode(file_get_contents($keyFile), true) : [];
}
if (!isset($this->_keys[$name]) || $regenerate) {
$this->_keys[$name] = $this->generateRandomKey($length);
file_put_contents($keyFile, json_encode($this->_keys));
}
return $this->_keys[$name];
}
/**
* Generates specified number of random bytes.
* Note that output may not be ASCII.
* @see generateRandomKey() if you need a string.
*
* @param integer $length the number of bytes to generate
* @throws Exception on failure.
* @return string the generated random bytes
*/
public function generateRandomBytes($length = 32)
{
if (!extension_loaded('mcrypt')) {
throw new InvalidConfigException('The mcrypt PHP extension is not installed.');
}
$bytes = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
if ($bytes === false) {
throw new Exception('Unable to generate random bytes.');
}
return $bytes;
}
/**
* Generates a random string of specified length.
* The string generated matches [A-Za-z0-9_.-]+
*
* @param integer $length the length of the key in characters
* @throws Exception Exception on failure.
* @return string the generated random key
*/
public function generateRandomKey($length = 32)
{
$bytes = $this->generateRandomBytes($length);
return strtr(StringHelper::byteSubstr(base64_encode($bytes), 0, $length), '+/=', '_-.');
}
/**
* Opens the mcrypt module.
* @return resource the mcrypt module handle.
* @throws InvalidConfigException if mcrypt extension is not installed
* @throws Exception if mcrypt initialization fails
*/
protected function openCryptModule()
{
if (!extension_loaded('mcrypt')) {
throw new InvalidConfigException('The mcrypt PHP extension is not installed.');
}
// AES version depending on crypt block size
$algorithmName = 'rijndael-' . ($this->cryptBlockSize * 8);
$module = @mcrypt_module_open($algorithmName, '', 'cbc', '');
if ($module === false) {
throw new Exception('Failed to initialize the mcrypt module.');
}
return $module;
}
/**
* Generates a secure hash from a password and a random salt.
*
* The generated hash can be stored in database (e.g. `CHAR(64) CHARACTER SET latin1` on MySQL).
* Later when a password needs to be validated, the hash can be fetched and passed
* to [[validatePassword()]]. For example,
*
* ~~~
* // generates the hash (usually done during user registration or when the password is changed)
* $hash = Yii::$app->getSecurity()->generatePasswordHash($password);
* // ...save $hash in database...
*
* // during login, validate if the password entered is correct using $hash fetched from database
* if (Yii::$app->getSecurity()->validatePassword($password, $hash) {
* // password is good
* } else {
* // password is bad
* }
* ~~~
*
* @param string $password The password to be hashed.
* @param integer $cost Cost parameter used by the Blowfish hash algorithm.
* The higher the value of cost,
* the longer it takes to generate the hash and to verify a password against it. Higher cost
* therefore slows down a brute-force attack. For best protection against brute for attacks,
* set it to the highest value that is tolerable on production servers. The time taken to
* compute the hash doubles for every increment by one of $cost. So, for example, if the
* hash takes 1 second to compute when $cost is 14 then then the compute time varies as
* 2^($cost - 14) seconds.
* @throws Exception on bad password parameter or cost parameter
* @return string The password hash string, ASCII and not longer than 64 characters.
* @see validatePassword()
*/
public function generatePasswordHash($password, $cost = 13)
{
switch ($this->passwordHashStrategy) {
case 'password_hash':
if (!function_exists('password_hash')) {
throw new InvalidConfigException('Password hash key strategy "password_hash" requires PHP >= 5.5.0, either upgrade your environment or use another strategy.');
}
return password_hash($password, PASSWORD_DEFAULT, ['cost' => $cost]);
case 'crypt':
$salt = $this->generateSalt($cost);
$hash = crypt($password, $salt);
if (!is_string($hash) || strlen($hash) < 32) {
throw new Exception('Unknown error occurred while generating hash.');
}
return $hash;
default:
throw new InvalidConfigException("Unknown password hash strategy '{$this->passwordHashStrategy}'");
}
}
/**
* Verifies a password against a hash.
* @param string $password The password to verify.
* @param string $hash The hash to verify the password against.
* @return boolean whether the password is correct.
* @throws InvalidParamException on bad password or hash parameters or if crypt() with Blowfish hash is not available.
* @throws InvalidConfigException on unsupported password hash strategy is configured.
* @see generatePasswordHash()
*/
public function validatePassword($password, $hash)
{
if (!is_string($password) || $password === '') {
throw new InvalidParamException('Password must be a string and cannot be empty.');
}
if (!preg_match('/^\$2[axy]\$(\d\d)\$[\.\/0-9A-Za-z]{22}/', $hash, $matches) || $matches[1] < 4 || $matches[1] > 30) {
throw new InvalidParamException('Hash is invalid.');
}
switch ($this->passwordHashStrategy) {
case 'password_hash':
if (!function_exists('password_verify')) {
throw new InvalidConfigException('Password hash key strategy "password_hash" requires PHP >= 5.5.0, either upgrade your environment or use another strategy.');
}
return password_verify($password, $hash);
case 'crypt':
$test = crypt($password, $hash);
$n = strlen($test);
if ($n < 32 || $n !== strlen($hash)) {
return false;
}
return $this->compareString($test, $hash);
default:
throw new InvalidConfigException("Unknown password hash strategy '{$this->passwordHashStrategy}'");
}
}
/**
* Generates a salt that can be used to generate a password hash.
*
* The PHP [crypt()](http://php.net/manual/en/function.crypt.php) built-in function
* requires, for the Blowfish hash algorithm, a salt string in a specific format:
* "$2a$", "$2x$" or "$2y$", a two digit cost parameter, "$", and 22 characters
* from the alphabet "./0-9A-Za-z".
*
* @param integer $cost the cost parameter
* @return string the random salt value.
* @throws InvalidParamException if the cost parameter is not between 4 and 31
*/
protected function generateSalt($cost = 13)
{
$cost = (int)$cost;
if ($cost < 4 || $cost > 31) {
throw new InvalidParamException('Cost must be between 4 and 31.');
}
// Get 20 * 8bits of random entropy
$rand = $this->generateRandomBytes(20);
// Add the microtime for a little more entropy.
$rand .= microtime(true);
// Mix the bits cryptographically into a 20-byte binary string.
$rand = sha1($rand, true);
// Form the prefix that specifies Blowfish algorithm and cost parameter.
$salt = sprintf("$2y$%02d$", $cost);
// Append the random salt data in the required base64 format.
$salt .= str_replace('+', '.', substr(base64_encode($rand), 0, 22));
return $salt;
}
/**
* Performs string comparison using timing attack resistant approach.
* @see http://codereview.stackexchange.com/questions/13512
* @param string $expected string to compare.
* @param string $actual string to compare.
* @return boolean whether strings are equal.
*/
protected function compareString($expected, $actual)
{
// timing attack resistant approach:
$diff = 0;
for ($i = 0; $i < StringHelper::byteLength($actual); $i++) {
$diff |= (ord($actual[$i]) ^ ord($expected[$i]));
}
return $diff === 0;
}
}