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<?php |
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namespace Coreproc\CryptoGuard; |
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use Coreproc\CryptoGuard\Exceptions\InvalidPayloadException; |
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use Exception; |
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class CryptoGuard |
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{ |
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private $passphrase; |
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private $key; |
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private $salt; |
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private $iv; |
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public function __construct($passphrase) |
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{ |
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$this->passphrase = $passphrase; |
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} |
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/** |
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* Encrypt a string |
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* |
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* @param string $plaintext |
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* @return string |
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*/ |
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public function encrypt($plaintext) |
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{ |
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$this->generateSalt(); |
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$this->generateIv(); |
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$this->generateKey($this->passphrase); |
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$ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $this->key, $plaintext, MCRYPT_MODE_CBC, $this->iv); |
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$dataReturn = array(); |
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$dataReturn['iv'] = base64_encode($this->iv); |
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$dataReturn['salt'] = base64_encode($this->salt); |
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$dataReturn['ciphertext'] = base64_encode($ciphertext); |
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$dataReturn['sig'] = base64_encode($this->hmacSign($ciphertext . $this->salt, $this->iv)); |
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return base64_encode(json_encode($dataReturn)); |
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} |
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/** |
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* Decrypt the encrypted string |
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* |
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* @param $dataEnciphered |
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* @return string |
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* @throws Exception |
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*/ |
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public function decrypt($dataEnciphered) |
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{ |
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$dataDecoded = json_decode(base64_decode($dataEnciphered), true); |
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$this->setIv(base64_decode($dataDecoded['iv'])); |
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$this->setSalt(base64_decode($dataDecoded['salt'])); |
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$this->generateKey($this->passphrase); |
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$ciphertext = base64_decode($dataDecoded['ciphertext']); |
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$originalSignature = base64_decode($dataDecoded['sig']); |
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// Attempt to verify signature |
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if ($this->hmacVerify($originalSignature . $ciphertext . $this->salt, $this->iv) == false) { |
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throw new InvalidPayloadException(); |
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} |
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return trim(mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $this->key, $ciphertext, MCRYPT_MODE_CBC, $this->iv)); |
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} |
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private function setSalt($salt) |
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{ |
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$this->salt = $salt; |
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} |
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private function generateSalt() |
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{ |
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$this->salt = mcrypt_create_iv(32, MCRYPT_DEV_RANDOM); // abuse IV function for random salt |
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} |
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private function setIv($iv) |
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{ |
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$this->iv = $iv; |
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} |
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private function generateIv() |
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{ |
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$this->iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC)); |
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} |
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private function generateKey($passphrase, $iterations = 10000, $length = 32) |
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{ |
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$this->key = hash_pbkdf2('sha256', $passphrase, $this->salt, $iterations, $length); |
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} |
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private function hmacSign($ciphertext, $key) |
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{ |
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return hash_hmac('sha256', $ciphertext, $key); |
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} |
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/** |
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* @param $bundle |
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* @param $key |
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* @return bool |
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*/ |
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private function hmacVerify($bundle, $key) |
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{ |
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$msgMAC = mb_substr($bundle, 0, 64, '8bit'); |
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$message = mb_substr($bundle, 64, null, '8bit'); |
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return hash_equals( |
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hash_hmac('sha256', $message, $key), |
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$msgMAC |
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); |
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} |
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} |
CoreProc /
crypto-guard
