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<?php |
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|
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namespace FluentForm\Framework\Encryption; |
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|
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use RuntimeException; |
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use FluentForm\Framework\Foundation\App; |
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use FluentForm\Framework\Encryption\EncryptException; |
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use FluentForm\Framework\Encryption\DecryptException; |
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|
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class Encrypter |
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{ |
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/** |
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* The encryption key. |
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* |
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* @var string |
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*/ |
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protected $key; |
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|
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/** |
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* The algorithm used for encryption. |
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* |
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* @var string |
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*/ |
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protected $cipher; |
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|
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/** |
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* The plugin slug key. |
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* |
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* @var string |
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*/ |
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protected $slug; |
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|
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/** |
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* The supported cipher algorithms and their properties. |
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* |
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* @var array |
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*/ |
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private static $supportedCiphers = [ |
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'aes-128-cbc' => ['size' => 16, 'aead' => false], |
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'aes-256-cbc' => ['size' => 32, 'aead' => false], |
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'aes-128-gcm' => ['size' => 16, 'aead' => true], |
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'aes-256-gcm' => ['size' => 32, 'aead' => true], |
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]; |
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|
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/** |
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* Create a new encrypter instance. |
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* |
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* @param string $key |
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* @param string $cipher |
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* @return void |
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* |
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* @throws \RuntimeException |
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*/ |
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public function __construct($key = null, $cipher = 'aes-128-cbc') |
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{ |
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$this->cipher = $cipher; |
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|
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$this->slug = $this->getSlug(); |
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|
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$key = $key ?: $this->getKey(); |
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|
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if (!static::supported($key, $this->cipher)) { |
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$ciphers = implode(', ', array_keys(self::$supportedCiphers)); |
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|
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throw new RuntimeException("Unsupported cipher or incorrect key length. Supported ciphers are: {$ciphers}."); |
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} |
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|
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$this->key = $key; |
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} |
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|
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/** |
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* Determine if the given key and cipher combination is valid. |
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* |
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* @param string $key |
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* @param string $cipher |
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* @return bool |
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*/ |
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public static function supported($key, $cipher) |
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{ |
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if (!isset(self::$supportedCiphers[strtolower($cipher)])) { |
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return false; |
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} |
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|
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return mb_strlen( |
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$key, '8bit' |
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) === self::$supportedCiphers[strtolower($cipher)]['size']; |
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} |
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|
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/** |
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* Create a new encryption key for the given cipher. |
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* |
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* @param string $cipher |
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* @return string |
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*/ |
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public static function generateKey($cipher) |
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{ |
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return random_bytes( |
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self::$supportedCiphers[strtolower($cipher)]['size'] ?? 32 |
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); |
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} |
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|
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/** |
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* Encrypt the given value. |
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* |
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* @param mixed $value |
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* @param bool $serialize |
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* @return string |
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* |
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* @throws \FluentForm\Framework\Encryption\EncryptException |
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*/ |
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public function encrypt($value, $serialize = true) |
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{ |
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$iv = random_bytes(openssl_cipher_iv_length(strtolower($this->cipher))); |
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|
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$value = \openssl_encrypt( |
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$serialize ? serialize($value) : $value, |
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strtolower($this->cipher), $this->key, 0, $iv, $tag |
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); |
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|
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if ($value === false) { |
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throw new EncryptException('Could not encrypt the data.'); |
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} |
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|
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$iv = base64_encode($iv); |
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$tag = base64_encode($tag ?? ''); |
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|
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$mac = self::$supportedCiphers[strtolower($this->cipher)]['aead'] |
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? '' // For AEAD-algorithms, the tag / MAC is returned by openssl_encrypt... |
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: $this->hash($iv, $value, $this->key); |
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|
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$json = json_encode(compact('iv', 'value', 'mac', 'tag'), JSON_UNESCAPED_SLASHES); |
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|
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if (json_last_error() !== JSON_ERROR_NONE) { |
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throw new EncryptException('Could not encrypt the data.'); |
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} |
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|
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return base64_encode($json); |
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} |
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|
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/** |
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* Encrypt a string without serialization. |
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* |
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* @param string $value |
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* @return string |
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* |
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* @throws \FluentForm\Framework\Encryption\EncryptException |
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*/ |
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public function encryptString($value) |
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{ |
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return $this->encrypt($value, false); |
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} |
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|
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/** |
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* Decrypt the given value. |
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* |
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* @param string $payload |
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* @param bool $unserialize |
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* @return mixed |
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* |
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* @throws \FluentForm\Framework\Encryption\DecryptException |
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*/ |
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public function decrypt($payload, $unserialize = true) |
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{ |
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$payload = $this->getJsonPayload($payload); |
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|
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$iv = base64_decode($payload['iv']); |
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|
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$this->ensureTagIsValid( |
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$tag = empty($payload['tag']) ? null : base64_decode($payload['tag']) |
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); |
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|
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$foundValidMac = false; |
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|
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// Here we will decrypt the value. If we are able to successfully decrypt it |
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// we will then unserialize it and return it out to the caller. If we are |
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// unable to decrypt this value we will throw out an exception message. |
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foreach ($this->getAllKeys() as $key) { |
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if ( |
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$this->shouldValidateMac() && |
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!($foundValidMac = $foundValidMac || $this->validMacForKey($payload, $key)) |
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) { |
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continue; |
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} |
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|
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$decrypted = \openssl_decrypt( |
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$payload['value'], strtolower($this->cipher), $key, 0, $iv, $tag ?? '' |
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); |
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|
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if ($decrypted !== false) { |
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break; |
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} |
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} |
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|
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if ($this->shouldValidateMac() && !$foundValidMac) { |
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throw new DecryptException('The MAC is invalid.'); |
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} |
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|
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if (($decrypted ?? false) === false) { |
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throw new DecryptException('Could not decrypt the data.'); |
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} |
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|
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return $unserialize ? unserialize($decrypted) : $decrypted; |
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} |
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|
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/** |
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* Decrypt the given string without unserialization. |
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* |
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* @param string $payload |
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* @return string |
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* |
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* @throws \FluentForm\Framework\Encryption\DecryptException |
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*/ |
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public function decryptString($payload) |
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{ |
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return $this->decrypt($payload, false); |
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} |
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|
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/** |
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* Create a MAC for the given value. |
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* |
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* @param string $iv |
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* @param mixed $value |
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* @param string $key |
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* @return string |
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*/ |
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protected function hash($iv, $value, $key) |
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{ |
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return hash_hmac('sha256', $iv.$value, $key); |
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} |
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|
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/** |
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* Get the JSON array from the given payload. |
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* |
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* @param string $payload |
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* @return array |
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* |
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* @throws \FluentForm\Framework\Encryption\DecryptException |
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*/ |
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protected function getJsonPayload($payload) |
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{ |
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if (!is_string($payload)) { |
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throw new DecryptException('The payload is invalid.'); |
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} |
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|
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$payload = json_decode(base64_decode($payload), true); |
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|
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// If the payload is not valid JSON or does not have the proper keys set we will |
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// assume it is invalid and bail out of the routine since we will not be able |
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// to decrypt the given value. We'll also check the MAC for this encryption. |
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if (!$this->validPayload($payload)) { |
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throw new DecryptException('The payload is invalid.'); |
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} |
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|
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return $payload; |
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} |
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|
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/** |
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* Verify that the encryption payload is valid. |
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* |
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* @param mixed $payload |
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* @return bool |
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*/ |
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protected function validPayload($payload) |
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{ |
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if (!is_array($payload)) { |
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return false; |
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} |
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|
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foreach (['iv', 'value', 'mac'] as $item) { |
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if (!isset($payload[$item]) || !is_string($payload[$item])) { |
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return false; |
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} |
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} |
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|
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if (isset($payload['tag']) && !is_string($payload['tag'])) { |
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return false; |
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} |
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|
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return strlen(base64_decode($payload['iv'], true)) === openssl_cipher_iv_length(strtolower($this->cipher)); |
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} |
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|
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/** |
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* Determine if the MAC for the given payload is valid for the primary key. |
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* |
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* @param array $payload |
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* @return bool |
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*/ |
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protected function validMac(array $payload) |
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{ |
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return $this->validMacForKey($payload, $this->key); |
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} |
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|
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/** |
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* Determine if the MAC is valid for the given payload and key. |
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* |
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* @param array $payload |
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* @param string $key |
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* @return bool |
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*/ |
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protected function validMacForKey($payload, $key) |
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{ |
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return hash_equals( |
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$this->hash($payload['iv'], $payload['value'], $key), $payload['mac'] |
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); |
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} |
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|
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/** |
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* Ensure the given tag is a valid tag given the selected cipher. |
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* |
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* @param string $tag |
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* @return void |
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*/ |
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protected function ensureTagIsValid($tag) |
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{ |
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if (self::$supportedCiphers[strtolower($this->cipher)]['aead'] && strlen($tag) !== 16) { |
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throw new DecryptException('Could not decrypt the data.'); |
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} |
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|
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if (!self::$supportedCiphers[strtolower($this->cipher)]['aead'] && is_string($tag)) { |
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throw new DecryptException('Unable to use tag because the cipher algorithm does not support AEAD.'); |
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} |
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} |
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|
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/** |
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* Determine if we should validate the MAC while decrypting. |
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* |
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* @return bool |
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*/ |
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protected function shouldValidateMac() |
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{ |
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return !self::$supportedCiphers[strtolower($this->cipher)]['aead']; |
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} |
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|
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/** |
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* Get the application encryption key. |
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* |
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* Developers may override the database key name using the filter: |
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* `{slug}.encryption.option_key` |
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* |
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* @return string |
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*/ |
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public function getSlug() |
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{ |
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$slug = App::config()->get('app.slug'); |
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|
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$default = $slug . '_enc_key'; |
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|
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/** |
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* Allow developer to override the encryption key option name. |
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* |
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* @param string $default Default option key name. |
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*/ |
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return App::applyFilters($slug . '.encryption.option_key', $default); |
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} |
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|
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/** |
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* Get the encryption key that the encrypter is currently using. |
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* |
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* @return string |
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*/ |
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public function getKey() |
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{ |
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if (!$key = get_option($this->slug)) { |
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|
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add_option($this->slug, base64_encode( |
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$this->generateKey($this->cipher) |
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)); |
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|
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$key = get_option($this->slug); |
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} |
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|
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return base64_decode($key); |
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} |
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|
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/** |
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* Get the current encryption key and all previous encryption keys. |
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* |
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* This is useful for key rotation, allowing decryption of data |
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* encrypted with older keys. |
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* |
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* @return array Array of binary encryption keys. |
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*/ |
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public function getAllKeys() |
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{ |
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$keys = [$this->key]; |
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|
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// Get the old keys option name, allowing override via filter |
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$oldKeysOption = App::applyFilters( |
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$this->slug . '.encryption.old_keys_option', |
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$this->slug . '_old_enc_key' |
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); |
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|
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$oldKeys = get_option($oldKeysOption, []); |
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|
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foreach ($oldKeys as $encodedKey) { |
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$decoded = base64_decode($encodedKey, true); |
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if ($decoded !== false) { |
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$keys[] = $decoded; |
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} |
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} |
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|
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return $keys; |
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} |
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|
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/** |
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* Rotate the encryption key. |
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* |
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* This method archives the current key in the old keys list, |
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* generates a new encryption key, stores it in the database, |
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* and updates the encrypter instance with the new key. |
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* |
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* @return void |
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*/ |
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public function rotateKey() |
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{ |
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$currentEncoded = base64_encode($this->key); |
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|
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// Get the old keys option name, allowing override via filter |
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$oldKeysOption = App::applyFilters( |
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$this->slug . '.encryption.old_keys_option', |
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$this->slug . '_old_enc_key' |
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); |
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|
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$oldKeys = get_option($oldKeysOption, []); |
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|
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// Add current key to old list if not already present |
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if (!in_array($currentEncoded, $oldKeys, true)) { |
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$oldKeys[] = $currentEncoded; |
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update_option($oldKeysOption, $oldKeys); |
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} |
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|
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// Generate and store new key |
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$newKey = base64_encode(static::generateKey($this->cipher)); |
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update_option($this->slug, $newKey); |
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|
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// Update instance property with decoded new key |
| 437 |
$this->key = base64_decode($newKey); |
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} |
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} |
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|
