<?php

namespace Google\Site_Kit_Dependencies\Firebase\JWT;

use DomainException;
use UnexpectedValueException;
/**
 * JSON Web Key implementation, based on this spec:
 * https://tools.ietf.org/html/draft-ietf-jose-json-web-key-41
 *
 * PHP version 5
 *
 * @category Authentication
 * @package  Authentication_JWT
 * @author   Bui Sy Nguyen <nguyenbs@gmail.com>
 * @license  http://opensource.org/licenses/BSD-3-Clause 3-clause BSD
 * @link     https://github.com/firebase/php-jwt
 */
class JWK
{
    /**
     * Parse a set of JWK keys
     *
     * @param array $jwks The JSON Web Key Set as an associative array
     *
     * @return array An associative array that represents the set of keys
     *
     * @throws InvalidArgumentException     Provided JWK Set is empty
     * @throws UnexpectedValueException     Provided JWK Set was invalid
     * @throws DomainException              OpenSSL failure
     *
     * @uses parseKey
     */
    public static function parseKeySet(array $jwks)
    {
        $keys = array();
        if (!isset($jwks['keys'])) {
            throw new \UnexpectedValueException('"keys" member must exist in the JWK Set');
        }
        if (empty($jwks['keys'])) {
            throw new \Google\Site_Kit_Dependencies\Firebase\JWT\InvalidArgumentException('JWK Set did not contain any keys');
        }
        foreach ($jwks['keys'] as $k => $v) {
            $kid = isset($v['kid']) ? $v['kid'] : $k;
            if ($key = self::parseKey($v)) {
                $keys[$kid] = $key;
            }
        }
        if (0 === \count($keys)) {
            throw new \UnexpectedValueException('No supported algorithms found in JWK Set');
        }
        return $keys;
    }
    /**
     * Parse a JWK key
     *
     * @param array $jwk An individual JWK
     *
     * @return resource|array An associative array that represents the key
     *
     * @throws InvalidArgumentException     Provided JWK is empty
     * @throws UnexpectedValueException     Provided JWK was invalid
     * @throws DomainException              OpenSSL failure
     *
     * @uses createPemFromModulusAndExponent
     */
    private static function parseKey(array $jwk)
    {
        if (empty($jwk)) {
            throw new \Google\Site_Kit_Dependencies\Firebase\JWT\InvalidArgumentException('JWK must not be empty');
        }
        if (!isset($jwk['kty'])) {
            throw new \UnexpectedValueException('JWK must contain a "kty" parameter');
        }
        switch ($jwk['kty']) {
            case 'RSA':
                if (\array_key_exists('d', $jwk)) {
                    throw new \UnexpectedValueException('RSA private keys are not supported');
                }
                if (!isset($jwk['n']) || !isset($jwk['e'])) {
                    throw new \UnexpectedValueException('RSA keys must contain values for both "n" and "e"');
                }
                $pem = self::createPemFromModulusAndExponent($jwk['n'], $jwk['e']);
                $publicKey = \openssl_pkey_get_public($pem);
                if (\false === $publicKey) {
                    throw new \DomainException('OpenSSL error: ' . \openssl_error_string());
                }
                return $publicKey;
            default:
                // Currently only RSA is supported
                break;
        }
    }
    /**
     * Create a public key represented in PEM format from RSA modulus and exponent information
     *
     * @param string $n The RSA modulus encoded in Base64
     * @param string $e The RSA exponent encoded in Base64
     *
     * @return string The RSA public key represented in PEM format
     *
     * @uses encodeLength
     */
    private static function createPemFromModulusAndExponent($n, $e)
    {
        $modulus = \Google\Site_Kit_Dependencies\Firebase\JWT\JWT::urlsafeB64Decode($n);
        $publicExponent = \Google\Site_Kit_Dependencies\Firebase\JWT\JWT::urlsafeB64Decode($e);
        $components = array('modulus' => \pack('Ca*a*', 2, self::encodeLength(\strlen($modulus)), $modulus), 'publicExponent' => \pack('Ca*a*', 2, self::encodeLength(\strlen($publicExponent)), $publicExponent));
        $rsaPublicKey = \pack('Ca*a*a*', 48, self::encodeLength(\strlen($components['modulus']) + \strlen($components['publicExponent'])), $components['modulus'], $components['publicExponent']);
        // sequence(oid(1.2.840.113549.1.1.1), null)) = rsaEncryption.
        $rsaOID = \pack('H*', '300d06092a864886f70d0101010500');
        // hex version of MA0GCSqGSIb3DQEBAQUA
        $rsaPublicKey = \chr(0) . $rsaPublicKey;
        $rsaPublicKey = \chr(3) . self::encodeLength(\strlen($rsaPublicKey)) . $rsaPublicKey;
        $rsaPublicKey = \pack('Ca*a*', 48, self::encodeLength(\strlen($rsaOID . $rsaPublicKey)), $rsaOID . $rsaPublicKey);
        $rsaPublicKey = "-----BEGIN PUBLIC KEY-----\r\n" . \chunk_split(\base64_encode($rsaPublicKey), 64) . '-----END PUBLIC KEY-----';
        return $rsaPublicKey;
    }
    /**
     * DER-encode the length
     *
     * DER supports lengths up to (2**8)**127, however, we'll only support lengths up to (2**8)**4.  See
     * {@link http://itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf#p=13 X.690 paragraph 8.1.3} for more information.
     *
     * @param int $length
     * @return string
     */
    private static function encodeLength($length)
    {
        if ($length <= 0x7f) {
            return \chr($length);
        }
        $temp = \ltrim(\pack('N', $length), \chr(0));
        return \pack('Ca*', 0x80 | \strlen($temp), $temp);
    }
}
