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505 lines
20 KiB
505 lines
20 KiB
<?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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* This component provides several configuration parameters, which allow tuning your own balance |
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* between high security and high performance. |
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* |
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* > Tip: you may add several `Security` components with different configurations to your application, |
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* this allows usage of different encryption strategies for different use cases or migrate encrypted data |
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* from outdated strategy to the new one. |
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* |
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* > Note: this class requires 'mcrypt' PHP extension. For the highest security level PHP version >= 5.5.0 is recommended. |
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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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* @var string strategy, which should be used to generate password hash. |
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* Available strategies: |
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* - 'password_hash' - use of PHP `password_hash()` function with PASSWORD_DEFAULT algorithm. This option is recommended, |
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* but it requires PHP version >= 5.5.0 |
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* - 'crypt' - use PHP `crypt()` function. |
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*/ |
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public $passwordHashStrategy = 'crypt'; |
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/** |
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* @var boolean whether to generate unique salt while deriving encryption key. |
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* If enabled (recommended) this option increases encrypted text length, but provide more security. |
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* If disabled this option reduces encrypted text length, but also reduces security. |
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*/ |
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public $useDeriveKeyUniqueSalt = true; |
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/** |
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* @var string the path or alias of a file that stores the secret keys automatically generated by [[getSecretKey()]]. |
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* The file must be writable by Web server process. It contains a JSON hash of key names and key values. |
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*/ |
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public $secretKeyFile = '@runtime/keys.json'; |
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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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$ivSize = mcrypt_enc_get_iv_size($module); |
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$iv = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM); |
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if ($this->useDeriveKeyUniqueSalt) { |
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$keySalt = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM); |
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$encrypted = $keySalt; |
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} else { |
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$keySalt = $iv; |
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$encrypted = ''; |
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} |
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$key = $this->deriveKey($password, $keySalt); |
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mcrypt_generic_init($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, $ivSize); |
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$keySalt = $iv; |
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$encrypted = StringHelper::byteSubstr($data, $ivSize, StringHelper::byteLength($data)); |
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if ($this->useDeriveKeyUniqueSalt) { |
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$iv = StringHelper::byteSubstr($encrypted, 0, $ivSize); |
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$encrypted = StringHelper::byteSubstr($encrypted, $ivSize, StringHelper::byteLength($encrypted)); |
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} |
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$key = $this->deriveKey($password, $keySalt); |
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mcrypt_generic_init($module, $key, $iv); |
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$decrypted = mdecrypt_generic($module, $encrypted); |
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mcrypt_generic_deinit($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, $this->cryptKeySize, true); |
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} else { |
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throw new InvalidConfigException('Security::$deriveKeyStrategy is set to "pbkdf2", which requires PHP >= 5.5.0. Either upgrade your run-time 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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private $_keys; |
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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, it will be automatically generated and saved in [[secretKeyFile]]. |
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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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* @param boolean $regenerate whether to regenerate a secret if it already exists |
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* @return string the secret key associated with the specified name |
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*/ |
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public function getSecretKey($name, $length = 32, $regenerate = false) |
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{ |
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$keyFile = Yii::getAlias($this->secretKeyFile); |
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if ($this->_keys === null) { |
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$this->_keys = is_file($keyFile) ? json_decode(file_get_contents($keyFile), true) : []; |
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} |
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if (!isset($this->_keys[$name]) || $regenerate) { |
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$this->_keys[$name] = $this->generateRandomKey($length); |
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file_put_contents($keyFile, json_encode($this->_keys)); |
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} |
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return $this->_keys[$name]; |
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} |
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/** |
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* Generates specified number of random bytes. |
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* Note that output may not be ASCII. |
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* @see generateRandomKey() if you need a string. |
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* |
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* @param integer $length the number of bytes to generate |
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* @throws Exception on failure. |
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* @return string the generated random bytes |
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*/ |
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public function generateRandomBytes($length = 32) |
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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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$bytes = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM); |
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if ($bytes === false) { |
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throw new Exception('Unable to generate random bytes.'); |
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} |
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return $bytes; |
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} |
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/** |
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* Generates a random string of specified length. |
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* The string generated matches [A-Za-z0-9_.-]+ |
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* |
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* @param integer $length the length of the key in characters |
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* @throws Exception Exception on failure. |
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* @return string the generated random key |
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*/ |
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public function generateRandomKey($length = 32) |
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{ |
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$bytes = $this->generateRandomBytes($length); |
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return strtr(StringHelper::byteSubstr(base64_encode($bytes), 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, $cost = 13) |
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{ |
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switch ($this->passwordHashStrategy) { |
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case 'password_hash': |
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if (!function_exists('password_hash')) { |
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throw new InvalidConfigException('Password hash key strategy "password_hash" requires PHP >= 5.5.0, either upgrade your environment or use another strategy.'); |
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} |
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return password_hash($password, PASSWORD_DEFAULT, ['cost' => $cost]); |
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case 'crypt': |
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$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 $hash; |
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default: |
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throw new InvalidConfigException("Unknown password hash strategy '{$this->passwordHashStrategy}'"); |
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} |
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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 $hash The hash to verify the password against. |
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* @return boolean whether the password is correct. |
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* @throws InvalidParamException on bad password or hash parameters or if crypt() with Blowfish hash is not available. |
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* @throws InvalidConfigException on unsupported password hash strategy is configured. |
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* @see generatePasswordHash() |
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*/ |
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public function validatePassword($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 || $matches[1] > 30) { |
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throw new InvalidParamException('Hash is invalid.'); |
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} |
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switch ($this->passwordHashStrategy) { |
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case 'password_hash': |
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if (!function_exists('password_verify')) { |
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throw new InvalidConfigException('Password hash key strategy "password_hash" requires PHP >= 5.5.0, either upgrade your environment or use another strategy.'); |
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} |
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return password_verify($password, $hash); |
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case 'crypt': |
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$test = crypt($password, $hash); |
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$n = strlen($test); |
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if ($n < 32 || $n !== strlen($hash)) { |
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return false; |
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} |
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return $this->compareString($test, $hash); |
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default: |
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throw new InvalidConfigException("Unknown password hash strategy '{$this->passwordHashStrategy}'"); |
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} |
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} |
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/** |
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* Generates a salt that can be used to generate a password hash. |
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* |
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* The PHP [crypt()](http://php.net/manual/en/function.crypt.php) built-in function |
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* requires, for the Blowfish hash algorithm, a salt string in a specific format: |
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* "$2a$", "$2x$" or "$2y$", a two digit cost parameter, "$", and 22 characters |
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* from the alphabet "./0-9A-Za-z". |
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* |
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* @param integer $cost the cost parameter |
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* @return string the random salt value. |
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* @throws InvalidParamException if the cost parameter is not between 4 and 31 |
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*/ |
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protected function generateSalt($cost = 13) |
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{ |
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$cost = (int)$cost; |
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if ($cost < 4 || $cost > 31) { |
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throw new InvalidParamException('Cost must be between 4 and 31.'); |
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} |
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// Get 20 * 8bits of random entropy |
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$rand = $this->generateRandomBytes(20); |
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// Add the microtime for a little more entropy. |
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$rand .= microtime(true); |
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// Mix the bits cryptographically into a 20-byte binary string. |
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$rand = sha1($rand, true); |
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// Form the prefix that specifies Blowfish algorithm and cost parameter. |
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$salt = sprintf("$2y$%02d$", $cost); |
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// Append the random salt data in the required base64 format. |
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$salt .= str_replace('+', '.', substr(base64_encode($rand), 0, 22)); |
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return $salt; |
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} |
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/** |
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* Performs string comparison using timing attack resistant approach. |
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* @see http://codereview.stackexchange.com/questions/13512 |
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* @param string $expected string to compare. |
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* @param string $actual string to compare. |
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* @return boolean whether strings are equal. |
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*/ |
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protected function compareString($expected, $actual) |
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{ |
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// timing attack resistant approach: |
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$diff = 0; |
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for ($i = 0; $i < StringHelper::byteLength($actual); $i++) { |
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$diff |= (ord($actual[$i]) ^ ord($expected[$i])); |
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} |
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return $diff === 0; |
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} |
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}
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