| 1 |
<?php |
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|
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namespace FluentForm\Framework\Encryption; |
| 4 |
|
| 5 |
use RuntimeException; |
| 6 |
use FluentForm\Framework\Foundation\App; |
| 7 |
use FluentForm\Framework\Encryption\EncryptException; |
| 8 |
use FluentForm\Framework\Encryption\DecryptException; |
| 9 |
|
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class Encrypter |
| 11 |
{ |
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/** |
| 13 |
* The encryption key. |
| 14 |
* |
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* @var string |
| 16 |
*/ |
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protected $key; |
| 18 |
|
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/** |
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* The algorithm used for encryption. |
| 21 |
* |
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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 $cipher |
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* @return string |
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* |
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* @throws \RuntimeException If the cipher is not in the supported list. |
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*/ |
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public static function generateKey($cipher) |
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{ |
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$cipher = strtolower($cipher); |
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|
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if (!isset(self::$supportedCiphers[$cipher])) { |
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$ciphers = implode(', ', array_keys(self::$supportedCiphers)); |
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|
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throw new RuntimeException( |
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"Unsupported cipher '{$cipher}'. Supported ciphers are: {$ciphers}." |
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); |
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} |
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|
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return random_bytes(self::$supportedCiphers[$cipher]['size']); |
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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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$foundValidMac = false; |
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|
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// Try each key (current + rotated) in turn. For non-AEAD ciphers, |
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// the MAC must be validated against THIS specific key — not a |
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// previous iteration's. Once a key passes its MAC check, attempt |
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// decryption with the same key. |
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foreach ($this->getAllKeys() as $key) { |
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if ($this->shouldValidateMac() && !$this->validMacForKey($payload, $key)) { |
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continue; |
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} |
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|
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$foundValidMac = true; |
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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 $item) { |
| 280 |
if (!isset($payload[$item]) || !is_string($payload[$item])) { |
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return false; |
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} |
| 283 |
} |
| 284 |
|
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if (isset($payload['tag']) && !is_string($payload['tag'])) { |
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return false; |
| 287 |
} |
| 288 |
|
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return strlen(base64_decode($payload['iv'], true)) === openssl_cipher_iv_length(strtolower($this->cipher)); |
| 290 |
} |
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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. |
| 294 |
* |
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* @param array $payload |
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* @return bool |
| 297 |
*/ |
| 298 |
protected function validMac(array $payload) |
| 299 |
{ |
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return $this->validMacForKey($payload, $this->key); |
| 301 |
} |
| 302 |
|
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/** |
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* Determine if the MAC is valid for the given payload and key. |
| 305 |
* |
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* @param array $payload |
| 307 |
* @param string $key |
| 308 |
* @return bool |
| 309 |
*/ |
| 310 |
protected function validMacForKey($payload, $key) |
| 311 |
{ |
| 312 |
return hash_equals( |
| 313 |
$this->hash($payload['iv'], $payload['value'], $key), $payload['mac'] |
| 314 |
); |
| 315 |
} |
| 316 |
|
| 317 |
/** |
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* Ensure the given tag is a valid tag given the selected cipher. |
| 319 |
* |
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* @param string $tag |
| 321 |
* @return void |
| 322 |
*/ |
| 323 |
protected function ensureTagIsValid($tag) |
| 324 |
{ |
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if (self::$supportedCiphers[strtolower($this->cipher)]['aead'] && strlen($tag) !== 16) { |
| 326 |
throw new DecryptException('Could not decrypt the data.'); |
| 327 |
} |
| 328 |
|
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if (!self::$supportedCiphers[strtolower($this->cipher)]['aead'] && is_string($tag)) { |
| 330 |
throw new DecryptException('Unable to use tag because the cipher algorithm does not support AEAD.'); |
| 331 |
} |
| 332 |
} |
| 333 |
|
| 334 |
/** |
| 335 |
* Determine if we should validate the MAC while decrypting. |
| 336 |
* |
| 337 |
* @return bool |
| 338 |
*/ |
| 339 |
protected function shouldValidateMac() |
| 340 |
{ |
| 341 |
return !self::$supportedCiphers[strtolower($this->cipher)]['aead']; |
| 342 |
} |
| 343 |
|
| 344 |
/** |
| 345 |
* Get the application encryption key. |
| 346 |
* |
| 347 |
* Developers may override the database key name using the filter: |
| 348 |
* `{slug}.encryption.option_key` |
| 349 |
* |
| 350 |
* @return string |
| 351 |
*/ |
| 352 |
public function getSlug() |
| 353 |
{ |
| 354 |
// Defensive: framework not bootstrapped (bare PHP, plugin |
| 355 |
// activation pre-init, early CLI). Fall back to a generic slug |
| 356 |
// so the constructor can still build a working encrypter. |
| 357 |
$app = App::getInstance(); |
| 358 |
|
| 359 |
if (!$app) { |
| 360 |
return 'wpfluent_enc_key'; |
| 361 |
} |
| 362 |
|
| 363 |
$slug = $app->config->get('app.slug'); |
| 364 |
|
| 365 |
$default = $slug . '_enc_key'; |
| 366 |
|
| 367 |
/** |
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* Allow developer to override the encryption key option name. |
| 369 |
* |
| 370 |
* @param string $default Default option key name. |
| 371 |
*/ |
| 372 |
return $app->applyFilters($slug . '.encryption.option_key', $default); |
| 373 |
} |
| 374 |
|
| 375 |
/** |
| 376 |
* Get the encryption key that the encrypter is currently using. |
| 377 |
* |
| 378 |
* @return string |
| 379 |
*/ |
| 380 |
public function getKey() |
| 381 |
{ |
| 382 |
if (!$key = get_option($this->slug)) { |
| 383 |
|
| 384 |
add_option($this->slug, base64_encode( |
| 385 |
$this->generateKey($this->cipher) |
| 386 |
)); |
| 387 |
|
| 388 |
$key = get_option($this->slug); |
| 389 |
} |
| 390 |
|
| 391 |
return base64_decode($key); |
| 392 |
} |
| 393 |
|
| 394 |
/** |
| 395 |
* Get the current encryption key and all previous encryption keys. |
| 396 |
* |
| 397 |
* This is useful for key rotation, allowing decryption of data |
| 398 |
* encrypted with older keys. |
| 399 |
* |
| 400 |
* @return array Array of binary encryption keys. |
| 401 |
*/ |
| 402 |
public function getAllKeys() |
| 403 |
{ |
| 404 |
$keys = [$this->key]; |
| 405 |
|
| 406 |
$oldKeysOption = $this->oldKeysOptionName(); |
| 407 |
|
| 408 |
$oldKeys = get_option($oldKeysOption, []); |
| 409 |
|
| 410 |
foreach ($oldKeys as $encodedKey) { |
| 411 |
$decoded = base64_decode($encodedKey, true); |
| 412 |
|
| 413 |
// Skip corrupted base64 and any key whose length doesn't match |
| 414 |
// the active cipher (otherwise it'd silently fail in the |
| 415 |
// decrypt loop, hiding the real cause). |
| 416 |
if ($decoded === false || !static::supported($decoded, $this->cipher)) { |
| 417 |
continue; |
| 418 |
} |
| 419 |
|
| 420 |
$keys[] = $decoded; |
| 421 |
} |
| 422 |
|
| 423 |
return $keys; |
| 424 |
} |
| 425 |
|
| 426 |
/** |
| 427 |
* Resolve the option name that stores rotated old keys. |
| 428 |
* Honors the {slug}.encryption.old_keys_option filter when the |
| 429 |
* framework App is bootstrapped; otherwise uses the default. |
| 430 |
* |
| 431 |
* @return string |
| 432 |
*/ |
| 433 |
protected function oldKeysOptionName() |
| 434 |
{ |
| 435 |
$default = $this->slug . '_old_enc_key'; |
| 436 |
|
| 437 |
$app = App::getInstance(); |
| 438 |
|
| 439 |
if (!$app) { |
| 440 |
return $default; |
| 441 |
} |
| 442 |
|
| 443 |
return $app->applyFilters( |
| 444 |
$this->slug . '.encryption.old_keys_option', |
| 445 |
$default |
| 446 |
); |
| 447 |
} |
| 448 |
|
| 449 |
/** |
| 450 |
* Rotate the encryption key. |
| 451 |
* |
| 452 |
* This method archives the current key in the old keys list, |
| 453 |
* generates a new encryption key, stores it in the database, |
| 454 |
* and updates the encrypter instance with the new key. |
| 455 |
* |
| 456 |
* @return void |
| 457 |
*/ |
| 458 |
public function rotateKey() |
| 459 |
{ |
| 460 |
$currentEncoded = base64_encode($this->key); |
| 461 |
|
| 462 |
$oldKeysOption = $this->oldKeysOptionName(); |
| 463 |
|
| 464 |
$oldKeys = get_option($oldKeysOption, []); |
| 465 |
|
| 466 |
// Add current key to old list if not already present |
| 467 |
if (!in_array($currentEncoded, $oldKeys, true)) { |
| 468 |
$oldKeys[] = $currentEncoded; |
| 469 |
} |
| 470 |
|
| 471 |
// Cap retention so the array doesn't grow unbounded across many |
| 472 |
// rotations. Keeps the MOST RECENT $cap entries; trimmed-out keys |
| 473 |
// mean any data still encrypted under them becomes undecryptable — |
| 474 |
// that's the documented contract of any retention policy. |
| 475 |
$cap = $this->oldKeysMax(); |
| 476 |
if (count($oldKeys) > $cap) { |
| 477 |
$oldKeys = array_values(array_slice($oldKeys, -$cap)); |
| 478 |
} |
| 479 |
|
| 480 |
update_option($oldKeysOption, $oldKeys); |
| 481 |
|
| 482 |
// Generate and store new key |
| 483 |
$newKey = base64_encode(static::generateKey($this->cipher)); |
| 484 |
update_option($this->slug, $newKey); |
| 485 |
|
| 486 |
// Update instance property with decoded new key |
| 487 |
$this->key = base64_decode($newKey); |
| 488 |
} |
| 489 |
|
| 490 |
/** |
| 491 |
* Maximum number of rotated keys to retain. |
| 492 |
* |
| 493 |
* Honors the {slug}.encryption.old_keys_max filter when the framework |
| 494 |
* App is bootstrapped. Default is 10, which covers ~10 weeks of weekly |
| 495 |
* rotation or ~10 years of annual rotation; bump the filter to keep |
| 496 |
* more historical keys around. |
| 497 |
* |
| 498 |
* @return int |
| 499 |
*/ |
| 500 |
protected function oldKeysMax() |
| 501 |
{ |
| 502 |
$default = 10; |
| 503 |
|
| 504 |
$app = App::getInstance(); |
| 505 |
|
| 506 |
if (!$app) { |
| 507 |
return $default; |
| 508 |
} |
| 509 |
|
| 510 |
return (int) $app->applyFilters( |
| 511 |
$this->slug . '.encryption.old_keys_max', |
| 512 |
$default |
| 513 |
); |
| 514 |
} |
| 515 |
} |
| 516 |
|
