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<?php |
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declare(strict_types = 1); |
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namespace Sop\JWX\JWE; |
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use Sop\JWX\JWE\CompressionAlgorithm\CompressionFactory; |
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use Sop\JWX\JWE\EncryptionAlgorithm\EncryptionAlgorithmFactory; |
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use Sop\JWX\JWE\KeyAlgorithm\KeyAlgorithmFactory; |
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use Sop\JWX\JWK\JWK; |
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use Sop\JWX\JWK\JWKSet; |
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use Sop\JWX\JWT\Header\Header; |
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use Sop\JWX\JWT\Header\JOSE; |
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use Sop\JWX\Util\Base64; |
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/** |
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* Class to represent JWE structure. |
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* |
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* @see https://tools.ietf.org/html/rfc7516#section-3 |
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*/ |
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class JWE |
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{ |
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/** |
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* Protected header. |
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* |
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* @var Header |
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*/ |
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protected $_protectedHeader; |
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/** |
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* Encrypted key. |
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* |
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* @var string |
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*/ |
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protected $_encryptedKey; |
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/** |
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* Initialization vector. |
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* |
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* @var string |
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*/ |
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protected $_iv; |
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/** |
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* Additional authenticated data. |
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* |
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* @var null|string |
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*/ |
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protected $_aad; |
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/** |
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* Ciphertext. |
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* |
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* @var string |
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*/ |
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protected $_ciphertext; |
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/** |
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* Authentication tag. |
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* |
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* @var string |
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*/ |
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protected $_authenticationTag; |
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/** |
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* Constructor. |
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* |
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* @param Header $protected_header JWE Protected Header |
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* @param string $encrypted_key Encrypted key |
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* @param string $iv Initialization vector |
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* @param string $ciphertext Ciphertext |
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* @param string $auth_tag Authentication tag |
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* @param null|string $aad Additional authenticated data |
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*/ |
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public function __construct(Header $protected_header, string $encrypted_key, |
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string $iv, string $ciphertext, string $auth_tag, ?string $aad = null) |
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{ |
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$this->_protectedHeader = $protected_header; |
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$this->_encryptedKey = $encrypted_key; |
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$this->_iv = $iv; |
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$this->_aad = $aad; |
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$this->_ciphertext = $ciphertext; |
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$this->_authenticationTag = $auth_tag; |
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} |
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/** |
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* Convert JWE to string. |
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* |
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* @return string |
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*/ |
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public function __toString(): string |
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{ |
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return $this->toCompact(); |
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} |
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/** |
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* Initialize from compact serialization. |
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* |
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* @param string $data |
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* |
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* @return self |
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*/ |
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public static function fromCompact(string $data): self |
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{ |
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return self::fromParts(explode('.', $data)); |
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} |
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/** |
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* Initialize from parts of compact serialization. |
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* |
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* @param array $parts |
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* |
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* @throws \UnexpectedValueException |
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* |
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* @return self |
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*/ |
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public static function fromParts(array $parts): self |
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{ |
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if (5 !== count($parts)) { |
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throw new \UnexpectedValueException( |
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'Invalid JWE compact serialization.'); |
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} |
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$header = Header::fromJSON(Base64::urlDecode($parts[0])); |
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$encrypted_key = Base64::urlDecode($parts[1]); |
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$iv = Base64::urlDecode($parts[2]); |
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$ciphertext = Base64::urlDecode($parts[3]); |
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$auth_tag = Base64::urlDecode($parts[4]); |
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return new self($header, $encrypted_key, $iv, $ciphertext, $auth_tag); |
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} |
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/** |
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* Initialize by encrypting the given payload. |
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* |
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* @param string $payload Payload |
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* @param KeyManagementAlgorithm $key_algo Key management algorithm |
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* @param ContentEncryptionAlgorithm $enc_algo Content encryption algorithm |
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* @param null|CompressionAlgorithm $zip_algo Optional compression algorithm |
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* @param null|Header $header Optional desired header. |
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* Algorithm specific parameters are |
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* automatically added. |
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* @param null|string $cek Optional content encryption key. |
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* Randomly enerated if not set. |
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* @param null|string $iv Optional initialization vector. |
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* Randomly generated if not set. |
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* |
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* @throws \RuntimeException If encrypt fails |
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* |
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* @return self |
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*/ |
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public static function encrypt(string $payload, |
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KeyManagementAlgorithm $key_algo, ContentEncryptionAlgorithm $enc_algo, |
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?CompressionAlgorithm $zip_algo = null, ?Header $header = null, |
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?string $cek = null, ?string $iv = null): self |
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{ |
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// if header was not given, initialize empty |
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if (!isset($header)) { |
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$header = new Header(); |
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} |
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// generate random CEK |
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if (!isset($cek)) { |
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$cek = $key_algo->cekForEncryption($enc_algo->keySize()); |
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} |
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// generate random IV |
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if (!isset($iv)) { |
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$iv = openssl_random_pseudo_bytes($enc_algo->ivSize()); |
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} |
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// compress |
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if (isset($zip_algo)) { |
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$payload = $zip_algo->compress($payload); |
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$header = $header->withParameters(...$zip_algo->headerParameters()); |
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} |
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return self::_encryptContent($payload, $cek, $iv, |
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$key_algo, $enc_algo, $header); |
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} |
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/** |
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* Decrypt the content using explicit algorithms. |
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* |
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* @param KeyManagementAlgorithm $key_algo Key management algorithm |
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* @param ContentEncryptionAlgorithm $enc_algo Content encryption algorithm |
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* |
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* @throws \RuntimeException If decrypt fails |
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* |
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* @return string Plaintext payload |
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*/ |
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public function decrypt(KeyManagementAlgorithm $key_algo, |
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ContentEncryptionAlgorithm $enc_algo): string |
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{ |
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// check that key management algorithm matches |
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if ($key_algo->algorithmParamValue() !== $this->algorithmName()) { |
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throw new \UnexpectedValueException( |
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'Invalid key management algorithm.'); |
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} |
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// check that encryption algorithm matches |
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if ($enc_algo->encryptionAlgorithmParamValue() !== $this->encryptionAlgorithmName()) { |
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throw new \UnexpectedValueException('Invalid encryption algorithm.'); |
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} |
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$header = $this->header(); |
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// decrypt content encryption key |
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$cek = $key_algo->decrypt($this->_encryptedKey, $header); |
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// decrypt payload |
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$aad = Base64::urlEncode($this->_protectedHeader->toJSON()); |
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$payload = $enc_algo->decrypt($this->_ciphertext, $cek, |
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$this->_iv, $aad, $this->_authenticationTag); |
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// decompress |
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if ($header->hasCompressionAlgorithm()) { |
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$payload = CompressionFactory::algoByHeader($header)->decompress($payload); |
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} |
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return $payload; |
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} |
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/** |
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* Decrypt content using given JWK. |
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* |
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* Key management and content encryption algorithms are determined from the |
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* header. |
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* |
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* @param JWK $jwk JSON Web Key |
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* |
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* @throws \RuntimeException If algorithm initialization fails |
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* |
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* @return string Plaintext payload |
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*/ |
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public function decryptWithJWK(JWK $jwk): string |
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{ |
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$header = $this->header(); |
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$key_algo = KeyManagementAlgorithm::fromJWK($jwk, $header); |
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$enc_algo = EncryptionAlgorithmFactory::algoByHeader($header); |
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return $this->decrypt($key_algo, $enc_algo); |
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} |
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/** |
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* Decrypt content using a key from the given JWK set. |
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* |
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* Correct key shall be sought by the key ID indicated by the header. |
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* |
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* @param JWKSet $set Set of JSON Web Keys |
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* |
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* @throws \RuntimeException If algorithm initialization fails |
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* |
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* @return string Plaintext payload |
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*/ |
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public function decryptWithJWKSet(JWKSet $set): string |
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{ |
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if (!count($set)) { |
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throw new \RuntimeException('No keys.'); |
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} |
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$header = $this->header(); |
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$factory = new KeyAlgorithmFactory($header); |
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$key_algo = $factory->algoByKeys($set); |
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$enc_algo = EncryptionAlgorithmFactory::algoByHeader($header); |
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return $this->decrypt($key_algo, $enc_algo); |
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} |
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/** |
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* Get JOSE header. |
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* |
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* @return JOSE |
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*/ |
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public function header(): JOSE |
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{ |
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return new JOSE($this->_protectedHeader); |
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} |
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/** |
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* Get the name of the key management algorithm. |
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* |
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* @return string |
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*/ |
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public function algorithmName(): string |
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{ |
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return $this->header()->algorithm()->value(); |
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} |
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/** |
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* Get the name of the encryption algorithm. |
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* |
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* @return string |
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*/ |
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public function encryptionAlgorithmName(): string |
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{ |
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return $this->header()->encryptionAlgorithm()->value(); |
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} |
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/** |
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* Get encrypted CEK. |
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* |
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* @return string |
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*/ |
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public function encryptedKey(): string |
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{ |
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return $this->_encryptedKey; |
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} |
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/** |
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* Get initialization vector. |
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* |
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* @return string |
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*/ |
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public function initializationVector(): string |
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{ |
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return $this->_iv; |
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} |
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/** |
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* Get ciphertext. |
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* |
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* @return string |
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*/ |
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public function ciphertext(): string |
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{ |
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return $this->_ciphertext; |
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} |
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/** |
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* Get authentication tag. |
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* |
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* @return string |
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*/ |
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public function authenticationTag(): string |
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{ |
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return $this->_authenticationTag; |
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} |
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/** |
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* Convert to compact serialization. |
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* |
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* @return string |
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*/ |
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public function toCompact(): string |
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{ |
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return Base64::urlEncode($this->_protectedHeader->toJSON()) . '.' . |
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Base64::urlEncode($this->_encryptedKey) . '.' . |
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Base64::urlEncode($this->_iv) . '.' . |
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Base64::urlEncode($this->_ciphertext) . '.' . |
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Base64::urlEncode($this->_authenticationTag); |
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} |
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/** |
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* Encrypt content with explicit parameters. |
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* |
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* @param string $plaintext Plaintext content to encrypt |
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* @param string $cek Content encryption key |
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* @param string $iv Initialization vector |
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* @param KeyManagementAlgorithm $key_algo Key management algorithm |
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* @param ContentEncryptionAlgorithm $enc_algo Content encryption algorithm |
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* @param Header $header Header |
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* |
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* @throws \UnexpectedValueException |
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* |
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* @return self |
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*/ |
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16 |
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private static function _encryptContent(string $plaintext, string $cek, |
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string $iv, KeyManagementAlgorithm $key_algo, |
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ContentEncryptionAlgorithm $enc_algo, Header $header): self |
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{ |
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// check that content encryption key has correct size |
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if (strlen($cek) !== $enc_algo->keySize()) { |
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throw new \UnexpectedValueException('Invalid key size.'); |
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} |
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// check that initialization vector has correct size |
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if (strlen($iv) !== $enc_algo->ivSize()) { |
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throw new \UnexpectedValueException('Invalid IV size.'); |
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} |
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// add key and encryption algorithm parameters to the header |
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$header = $header->withParameters(...$key_algo->headerParameters()) |
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->withParameters(...$enc_algo->headerParameters()); |
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// encrypt the content encryption key |
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$encrypted_key = $key_algo->encrypt($cek, $header); |
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// sanity check that header wasn't unset via reference |
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14 |
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if (!$header instanceof Header) { |
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throw new \RuntimeException('Broken key algorithm.'); |
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} |
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// additional authenticated data |
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13 |
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$aad = Base64::urlEncode($header->toJSON()); |
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// encrypt |
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13 |
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[$ciphertext, $auth_tag] = $enc_algo->encrypt($plaintext, $cek, $iv, $aad); |
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// TODO: should aad be passed |
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13 |
|
return new self($header, $encrypted_key, $iv, $ciphertext, $auth_tag); |
380
|
|
|
} |
381
|
|
|
} |
382
|
|
|
|