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<?php |
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|
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namespace Firebase\JWT; |
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|
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use DomainException; |
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use UnexpectedValueException; |
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|
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/** |
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* JSON Web Key implementation, based on this spec: |
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* https://tools.ietf.org/html/draft-ietf-jose-json-web-key-41 |
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* |
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* PHP version 5 |
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* |
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* @category Authentication |
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* @package Authentication_JWT |
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* @author Bui Sy Nguyen <nguyenbs@gmail.com> |
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* @license http://opensource.org/licenses/BSD-3-Clause 3-clause BSD |
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* @link https://github.com/firebase/php-jwt |
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*/ |
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class JWK |
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{ |
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/** |
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* Parse a set of JWK keys |
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* |
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* @param array $jwks The JSON Web Key Set as an associative array |
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* |
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* @return array An associative array that represents the set of keys |
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* |
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* @throws InvalidArgumentException Provided JWK Set is empty |
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* @throws UnexpectedValueException Provided JWK Set was invalid |
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* @throws DomainException OpenSSL failure |
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* |
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* @uses parseKey |
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*/ |
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public static function parseKeySet(array $jwks) |
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{ |
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$keys = array(); |
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|
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if (!isset($jwks['keys'])) { |
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throw new UnexpectedValueException('"keys" member must exist in the JWK Set'); |
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} |
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if (empty($jwks['keys'])) { |
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throw new InvalidArgumentException('JWK Set did not contain any keys'); |
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} |
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|
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foreach ($jwks['keys'] as $k => $v) { |
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$kid = isset($v['kid']) ? $v['kid'] : $k; |
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if ($key = self::parseKey($v)) { |
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$keys[$kid] = $key; |
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} |
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} |
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|
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if (0 === \count($keys)) { |
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throw new UnexpectedValueException('No supported algorithms found in JWK Set'); |
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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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* Parse a JWK key |
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* |
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* @param array $jwk An individual JWK |
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* |
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* @return resource|array An associative array that represents the key |
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* |
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* @throws InvalidArgumentException Provided JWK is empty |
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* @throws UnexpectedValueException Provided JWK was invalid |
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* @throws DomainException OpenSSL failure |
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* |
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* @uses createPemFromModulusAndExponent |
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*/ |
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private static function parseKey(array $jwk) |
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{ |
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if (empty($jwk)) { |
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throw new InvalidArgumentException('JWK must not be empty'); |
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} |
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if (!isset($jwk['kty'])) { |
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throw new UnexpectedValueException('JWK must contain a "kty" parameter'); |
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} |
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|
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switch ($jwk['kty']) { |
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case 'RSA': |
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if (\array_key_exists('d', $jwk)) { |
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throw new UnexpectedValueException('RSA private keys are not supported'); |
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} |
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if (!isset($jwk['n']) || !isset($jwk['e'])) { |
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throw new UnexpectedValueException('RSA keys must contain values for both "n" and "e"'); |
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} |
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|
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$pem = self::createPemFromModulusAndExponent($jwk['n'], $jwk['e']); |
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$publicKey = \openssl_pkey_get_public($pem); |
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if (false === $publicKey) { |
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throw new DomainException( |
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'OpenSSL error: ' . \openssl_error_string() |
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); |
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} |
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return $publicKey; |
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default: |
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// Currently only RSA is supported |
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break; |
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} |
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} |
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|
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/** |
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* Create a public key represented in PEM format from RSA modulus and exponent information |
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* |
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* @param string $n The RSA modulus encoded in Base64 |
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* @param string $e The RSA exponent encoded in Base64 |
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* |
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* @return string The RSA public key represented in PEM format |
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* |
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* @uses encodeLength |
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*/ |
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private static function createPemFromModulusAndExponent($n, $e) |
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{ |
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$modulus = JWT::urlsafeB64Decode($n); |
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$publicExponent = JWT::urlsafeB64Decode($e); |
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|
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$components = array( |
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'modulus' => \pack('Ca*a*', 2, self::encodeLength(\strlen($modulus)), $modulus), |
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'publicExponent' => \pack('Ca*a*', 2, self::encodeLength(\strlen($publicExponent)), $publicExponent) |
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); |
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|
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$rsaPublicKey = \pack( |
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'Ca*a*a*', |
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48, |
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self::encodeLength(\strlen($components['modulus']) + \strlen($components['publicExponent'])), |
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$components['modulus'], |
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$components['publicExponent'] |
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); |
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|
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// sequence(oid(1.2.840.113549.1.1.1), null)) = rsaEncryption. |
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$rsaOID = \pack('H*', '300d06092a864886f70d0101010500'); // hex version of MA0GCSqGSIb3DQEBAQUA |
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$rsaPublicKey = \chr(0) . $rsaPublicKey; |
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$rsaPublicKey = \chr(3) . self::encodeLength(\strlen($rsaPublicKey)) . $rsaPublicKey; |
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|
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$rsaPublicKey = \pack( |
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'Ca*a*', |
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48, |
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self::encodeLength(\strlen($rsaOID . $rsaPublicKey)), |
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$rsaOID . $rsaPublicKey |
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); |
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|
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$rsaPublicKey = "-----BEGIN PUBLIC KEY-----\r\n" . |
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\chunk_split(\base64_encode($rsaPublicKey), 64) . |
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'-----END PUBLIC KEY-----'; |
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|
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return $rsaPublicKey; |
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} |
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|
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/** |
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* DER-encode the length |
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* |
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* DER supports lengths up to (2**8)**127, however, we'll only support lengths up to (2**8)**4. See |
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* {@link http://itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf#p=13 X.690 paragraph 8.1.3} for more information. |
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* |
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* @param int $length |
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* @return string |
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*/ |
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private static function encodeLength($length) |
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{ |
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if ($length <= 0x7F) { |
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return \chr($length); |
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} |
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|
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$temp = \ltrim(\pack('N', $length), \chr(0)); |
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|
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return \pack('Ca*', 0x80 | \strlen($temp), $temp); |
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} |
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} |
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