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<?php
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/**
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* @link http://www.yiiframework.com/
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* @copyright Copyright (c) 2008 Yii Software LLC
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* @license http://www.yiiframework.com/license/
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*/
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namespace yii\base;
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use yii\helpers\StringHelper;
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use Yii;
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/**
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* Security provides a set of methods to handle common security-related tasks.
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*
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* In particular, Security supports the following features:
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*
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* - Encryption/decryption: [[encrypt()]] and [[decrypt()]]
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* - Data tampering prevention: [[hashData()]] and [[validateData()]]
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* - Password validation: [[generatePasswordHash()]] and [[validatePassword()]]
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*
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* Additionally, Security provides [[getSecretKey()]] to support generating
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* named secret keys. These secret keys, once generated, will be stored in a file
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* and made available in future requests.
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*
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* @author Qiang Xue <qiang.xue@gmail.com>
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* @author Tom Worster <fsb@thefsb.org>
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* @author Klimov Paul <klimov.paul@gmail.com>
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* @since 2.0
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*/
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class Security extends Component
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{
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/**
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* @var integer crypt block size in bytes.
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* For AES-128, AES-192, block size is 128-bit (16 bytes).
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* For AES-256, block size is 256-bit (32 bytes).
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* Recommended value: 32
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*/
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public $cryptBlockSize = 32;
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/**
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* @var integer crypt key size in bytes.
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* For AES-192, key size is 192-bit (24 bytes).
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* For AES-256, key size is 256-bit (32 bytes).
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* Recommended value: 32
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*/
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public $cryptKeySize = 32;
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/**
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* @var string derivation hash algorithm name.
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* Recommended value: 'sha256'
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*/
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public $derivationHash = 'sha256';
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/**
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* @var integer derivation iterations count.
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* Recommended value: 1000000
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*/
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public $derivationIterations = 1000000;
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/**
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* @var string strategy, which should be used to derive a key for encryption.
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* Available strategies:
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* - 'pbkdf2' - PBKDF2 key derivation, this option is recommended, but it requires PHP version >= 5.5.0
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* - 'hmac' - HMAC hash key derivation.
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*/
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public $deriveKeyStrategy = 'hmac';
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/**
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* Encrypts data.
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* @param string $data data to be encrypted.
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* @param string $password the encryption password
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* @return string the encrypted data
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* @throws Exception if PHP Mcrypt extension is not loaded or failed to be initialized
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* @see decrypt()
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*/
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public function encrypt($data, $password)
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{
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$module = $this->openCryptModule();
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$data = $this->addPadding($data);
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$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($module), MCRYPT_DEV_URANDOM);
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$key = $this->deriveKey($password, $iv);
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mcrypt_generic_init($module, $key, $iv);
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$encrypted = $iv . mcrypt_generic($module, $data);
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mcrypt_generic_deinit($module);
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mcrypt_module_close($module);
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return $encrypted;
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}
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/**
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* Decrypts data
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* @param string $data data to be decrypted.
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* @param string $password the decryption password
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* @return string the decrypted data
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* @throws Exception if PHP Mcrypt extension is not loaded or failed to be initialized
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* @see encrypt()
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*/
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public function decrypt($data, $password)
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{
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if ($data === null) {
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return null;
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}
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$module = $this->openCryptModule();
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$ivSize = mcrypt_enc_get_iv_size($module);
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$iv = StringHelper::byteSubstr($data, 0, $ivSize);
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$key = $this->deriveKey($password, $iv);
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mcrypt_generic_init($module, $key, $iv);
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$decrypted = mdecrypt_generic($module, StringHelper::byteSubstr($data, $ivSize, StringHelper::byteLength($data)));
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mcrypt_generic_deinit($module);
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mcrypt_module_close($module);
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return $this->stripPadding($decrypted);
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}
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/**
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* Adds a padding to the given data (PKCS #7).
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* @param string $data the data to pad
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* @return string the padded data
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*/
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protected function addPadding($data)
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{
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$pad = $this->cryptBlockSize - (StringHelper::byteLength($data) % $this->cryptBlockSize);
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return $data . str_repeat(chr($pad), $pad);
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}
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/**
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* Strips the padding from the given data.
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* @param string $data the data to trim
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* @return string the trimmed data
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*/
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protected function stripPadding($data)
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{
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$end = StringHelper::byteSubstr($data, -1, null);
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$last = ord($end);
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$n = StringHelper::byteLength($data) - $last;
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if (StringHelper::byteSubstr($data, $n, null) == str_repeat($end, $last)) {
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return StringHelper::byteSubstr($data, 0, $n);
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}
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return false;
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}
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/**
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* Derives a key from the given password (PBKDF2).
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* @param string $password the source password
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* @param string $salt the random salt
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* @throws InvalidConfigException if unsupported derive key strategy is configured.
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* @return string the derived key
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*/
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protected function deriveKey($password, $salt)
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{
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switch ($this->deriveKeyStrategy) {
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case 'pbkdf2':
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return $this->deriveKeyPbkdf2($password, $salt);
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case 'hmac':
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return $this->deriveKeyHmac($password, $salt);
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default:
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throw new InvalidConfigException("Unknown Derive key strategy '{$this->deriveKeyStrategy}'");
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}
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}
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/**
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* Derives a key from the given password using PBKDF2.
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* @param string $password the source password
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* @param string $salt the random salt
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* @throws InvalidConfigException if environment does not allows PBKDF2.
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* @return string the derived key
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*/
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protected function deriveKeyPbkdf2($password, $salt)
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{
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if (function_exists('hash_pbkdf2')) {
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return hash_pbkdf2($this->derivationHash, $password, $salt, $this->derivationIterations, $this->cryptKeySize, true);
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} else {
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throw new InvalidConfigException('Derive key strategy "pbkdf2" requires PHP >= 5.5.0, either upgrade your environment or use another strategy.');
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}
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}
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/**
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* Derives a key from the given password using HMAC.
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* @param string $password the source password
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* @param string $salt the random salt
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* @return string the derived key
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*/
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protected function deriveKeyHmac($password, $salt)
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{
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$hmac = hash_hmac($this->derivationHash, $salt . pack('N', 1), $password, true);
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$xorsum = $hmac;
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for ($i = 1; $i < $this->derivationIterations; $i++) {
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$hmac = hash_hmac($this->derivationHash, $hmac, $password, true);
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$xorsum ^= $hmac;
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}
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return substr($xorsum, 0, $this->cryptKeySize);
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}
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/**
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* Prefixes data with a keyed hash value so that it can later be detected if it is tampered.
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* @param string $data the data to be protected
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* @param string $key the secret key to be used for generating hash
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* @param string $algorithm the hashing algorithm (e.g. "md5", "sha1", "sha256", etc.). Call PHP "hash_algos()"
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* function to see the supported hashing algorithms on your system.
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* @return string the data prefixed with the keyed hash
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* @see validateData()
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* @see getSecretKey()
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*/
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public function hashData($data, $key, $algorithm = 'sha256')
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{
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return hash_hmac($algorithm, $data, $key) . $data;
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}
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/**
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* Validates if the given data is tampered.
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* @param string $data the data to be validated. The data must be previously
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* generated by [[hashData()]].
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* @param string $key the secret key that was previously used to generate the hash for the data in [[hashData()]].
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* @param string $algorithm the hashing algorithm (e.g. "md5", "sha1", "sha256", etc.). Call PHP "hash_algos()"
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* function to see the supported hashing algorithms on your system. This must be the same
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* as the value passed to [[hashData()]] when generating the hash for the data.
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* @return string the real data with the hash stripped off. False if the data is tampered.
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* @see hashData()
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*/
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public function validateData($data, $key, $algorithm = 'sha256')
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{
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$hashSize = StringHelper::byteLength(hash_hmac($algorithm, 'test', $key));
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$n = StringHelper::byteLength($data);
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if ($n >= $hashSize) {
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$hash = StringHelper::byteSubstr($data, 0, $hashSize);
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$pureData = StringHelper::byteSubstr($data, $hashSize, $n - $hashSize);
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$calculatedHash = hash_hmac($algorithm, $pureData, $key);
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if ($this->compareString($hash, $calculatedHash)) {
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return $pureData;
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} else {
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return false;
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}
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} else {
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return false;
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}
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}
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/**
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* Returns a secret key associated with the specified name.
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* If the secret key does not exist, a random key will be generated
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* and saved in the file "keys.json" under the application's runtime directory
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* so that the same secret key can be returned in future requests.
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* @param string $name the name that is associated with the secret key
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* @param integer $length the length of the key that should be generated if not exists
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* @return string the secret key associated with the specified name
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*/
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public function getSecretKey($name, $length = 32)
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{
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static $keys;
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$keyFile = Yii::$app->getRuntimePath() . '/keys.json';
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if ($keys === null) {
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$keys = [];
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if (is_file($keyFile)) {
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$keys = json_decode(file_get_contents($keyFile), true);
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}
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}
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if (!isset($keys[$name])) {
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$keys[$name] = $this->generateRandomKey($length);
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file_put_contents($keyFile, json_encode($keys));
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}
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return $keys[$name];
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}
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/**
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* Generates a random key. The key may contain uppercase and lowercase latin letters, digits, underscore, dash and dot.
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* Note: for delivering high security key, this method requires PHP 'mcrypt' extension.
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* @param integer $length the length of the key that should be generated
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* @return string the generated random key
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*/
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public function generateRandomKey($length = 32)
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{
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if (function_exists('mcrypt_create_iv')) {
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return mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
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}
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$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-.';
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return substr(str_shuffle(str_repeat($chars, 5)), 0, $length);
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}
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/**
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* Opens the mcrypt module.
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* @return resource the mcrypt module handle.
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* @throws InvalidConfigException if mcrypt extension is not installed
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* @throws Exception if mcrypt initialization fails
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*/
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protected function openCryptModule()
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{
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if (!extension_loaded('mcrypt')) {
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throw new InvalidConfigException('The mcrypt PHP extension is not installed.');
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}
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// AES version depending on crypt block size
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$algorithmName = 'rijndael-' . ($this->cryptBlockSize * 8);
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$module = @mcrypt_module_open($algorithmName, '', 'cbc', '');
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if ($module === false) {
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throw new Exception('Failed to initialize the mcrypt module.');
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}
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return $module;
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}
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/**
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* Generates a secure hash from a password and a random salt.
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*
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* The generated hash can be stored in database (e.g. `CHAR(64) CHARACTER SET latin1` on MySQL).
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* Later when a password needs to be validated, the hash can be fetched and passed
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* to [[validatePassword()]]. For example,
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*
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* ~~~
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* // generates the hash (usually done during user registration or when the password is changed)
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* $hash = Yii::$app->getSecurity()->generatePasswordHash($password);
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* // ...save $hash in database...
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*
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* // during login, validate if the password entered is correct using $hash fetched from database
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* if (Yii::$app->getSecurity()->validatePassword($password, $hash) {
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* // password is good
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* } else {
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* // password is bad
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* }
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* ~~~
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*
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* @param string $password The password to be hashed.
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* @param integer $cost Cost parameter used by the Blowfish hash algorithm.
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* The higher the value of cost,
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* the longer it takes to generate the hash and to verify a password against it. Higher cost
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* therefore slows down a brute-force attack. For best protection against brute for attacks,
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* set it to the highest value that is tolerable on production servers. The time taken to
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* compute the hash doubles for every increment by one of $cost. So, for example, if the
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* hash takes 1 second to compute when $cost is 14 then then the compute time varies as
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* 2^($cost - 14) seconds.
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* @throws Exception on bad password parameter or cost parameter
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* @return string The password hash string, ASCII and not longer than 64 characters.
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* @see validatePassword()
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*/
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public function generatePasswordHash($password, $cost = 13)
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{
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$salt = $this->generateSalt($cost);
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$hash = crypt($password, $salt);
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if (!is_string($hash) || strlen($hash) < 32) {
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throw new Exception('Unknown error occurred while generating hash.');
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}
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return $hash;
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}
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/**
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* Verifies a password against a hash.
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* @param string $password The password to verify.
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* @param string $hash The hash to verify the password against.
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* @return boolean whether the password is correct.
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* @throws InvalidParamException on bad password or hash parameters or if crypt() with Blowfish hash is not available.
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* @see generatePasswordHash()
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*/
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public function validatePassword($password, $hash)
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{
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if (!is_string($password) || $password === '') {
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throw new InvalidParamException('Password must be a string and cannot be empty.');
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}
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|
|
|
|
|
|
|
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.');
|
|
|
|
}
|
|
|
|
|
|
|
|
$test = crypt($password, $hash);
|
|
|
|
$n = strlen($test);
|
|
|
|
if ($n < 32 || $n !== strlen($hash)) {
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
|
|
|
return $this->compareString($test, $hash);
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* 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->generateRandomKey(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;
|
|
|
|
}
|
|
|
|
}
|