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<?php |
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declare(strict_types = 1); |
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namespace Sop\JWX\JWE\EncryptionAlgorithm; |
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use Sop\GCM\Cipher\Cipher; |
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use Sop\GCM\Exception\AuthenticationException as GCMAuthException; |
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use Sop\GCM\GCM; |
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use Sop\JWX\JWE\ContentEncryptionAlgorithm; |
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use Sop\JWX\JWE\Exception\AuthenticationException; |
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use Sop\JWX\JWT\Parameter\EncryptionAlgorithmParameter; |
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/** |
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* Base class for algorithms implementing AES in Galois/Counter mode. |
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* |
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* @see https://tools.ietf.org/html/rfc7518#section-5.3 |
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*/ |
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abstract class AESGCMAlgorithm implements ContentEncryptionAlgorithm |
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{ |
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/** |
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* {@inheritdoc} |
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*/ |
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public function encrypt(string $plaintext, string $key, string $iv, |
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string $aad): array |
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{ |
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$this->_validateKey($key); |
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$this->_validateIV($iv); |
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[$ciphertext, $auth_tag] = $this->_getGCM() |
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->encrypt($plaintext, $aad, $key, $iv); |
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return [$ciphertext, $auth_tag]; |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function decrypt(string $ciphertext, string $key, string $iv, |
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string $aad, string $auth_tag): string |
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{ |
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$this->_validateKey($key); |
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$this->_validateIV($iv); |
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try { |
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$plaintext = $this->_getGCM() |
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->decrypt($ciphertext, $auth_tag, $aad, $key, $iv); |
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} catch (GCMAuthException $e) { |
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throw new AuthenticationException('Message authentication failed.'); |
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} |
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return $plaintext; |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function ivSize(): int |
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{ |
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return 12; |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function headerParameters(): array |
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{ |
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return [EncryptionAlgorithmParameter::fromAlgorithm($this)]; |
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} |
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/** |
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* Get GCM Cipher instance. |
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* |
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* @return Cipher |
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*/ |
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abstract protected function _getGCMCipher(): Cipher; |
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/** |
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* Get GCM instance. |
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* |
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* @return GCM |
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*/ |
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final protected function _getGCM(): GCM |
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{ |
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return new GCM($this->_getGCMCipher(), 16); |
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} |
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/** |
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* Check that key is valid. |
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* |
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* @param string $key |
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* |
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* @throws \RuntimeException |
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*/ |
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final protected function _validateKey(string $key): void |
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{ |
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if (strlen($key) !== $this->keySize()) { |
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throw new \RuntimeException('Invalid key size.'); |
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} |
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} |
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/** |
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* Check that IV is valid. |
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* |
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* @param string $iv |
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* |
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* @throws \RuntimeException |
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*/ |
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final protected function _validateIV(string $iv): void |
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{ |
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if (strlen($iv) !== $this->ivSize()) { |
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throw new \RuntimeException('Invalid IV length.'); |
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} |
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} |
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} |
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sop /
jwx
