<?php

namespace Firebase\JWT;

use DomainException;
use InvalidArgumentException;
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
{

>     private const OID = '1.2.840.10045.2.1';
    /**
>     private const ASN1_OBJECT_IDENTIFIER = 0x06;
     * Parse a set of JWK keys
>     private const ASN1_SEQUENCE = 0x10; // also defined in JWT
     *
>     private const ASN1_BIT_STRING = 0x03;
     * @param array $jwks The JSON Web Key Set as an associative array
>     private const EC_CURVES = [
     *
>         'P-256' => '1.2.840.10045.3.1.7', // Len: 64
     * @return array<string, Key> An associative array of key IDs (kid) to Key objects
>         'secp256k1' => '1.3.132.0.10', // Len: 64
     *
>         // 'P-384' => '1.3.132.0.34', // Len: 96 (not yet supported)
     * @throws InvalidArgumentException     Provided JWK Set is empty
>         // 'P-521' => '1.3.132.0.35', // Len: 132 (not supported)
     * @throws UnexpectedValueException     Provided JWK Set was invalid
>     ];
     * @throws DomainException              OpenSSL failure
> 



<      * @param array $jwks The JSON Web Key Set as an associative array



>      * @param array<mixed> $jwks The JSON Web Key Set as an associative array
>      * @param string       $defaultAlg The algorithm for the Key object if "alg" is not set in the
>      *                                 JSON Web Key Set


     * @uses parseKey
     */

<     public static function parseKeySet(array $jwks)



>     public static function parseKeySet(array $jwks, string $defaultAlg = null): array


    {

<         $keys = array();



>         $keys = [];



        if (!isset($jwks['keys'])) {
            throw new UnexpectedValueException('"keys" member must exist in the JWK Set');
        }

> 


        if (empty($jwks['keys'])) {
            throw new 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 ($key = self::parseKey($v, $defaultAlg)) {
>                 $keys[(string) $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



>      * @param array<mixed> $jwk An individual JWK
>      * @param string       $defaultAlg The algorithm for the Key object if "alg" is not set in the
>      *                                 JSON Web Key Set


     *
     * @return Key The key object for the JWK
     *
     * @throws InvalidArgumentException     Provided JWK is empty
     * @throws UnexpectedValueException     Provided JWK was invalid
     * @throws DomainException              OpenSSL failure
     *
     * @uses createPemFromModulusAndExponent
     */

<     public static function parseKey(array $jwk)



>     public static function parseKey(array $jwk, string $defaultAlg = null): ?Key


    {
        if (empty($jwk)) {
            throw new InvalidArgumentException('JWK must not be empty');
        }

> 


        if (!isset($jwk['kty'])) {
            throw new UnexpectedValueException('JWK must contain a "kty" parameter');
        }

> 


        if (!isset($jwk['alg'])) {

<             // The "alg" parameter is optional in a KTY, but is required for parsing in
<             // this library. Add it manually to your JWK array if it doesn't already exist.



>             if (\is_null($defaultAlg)) {
>                 // The "alg" parameter is optional in a KTY, but an algorithm is required
>                 // for parsing in this library. Use the $defaultAlg parameter when parsing the
>                 // key set in order to prevent this error.


            // @see https://datatracker.ietf.org/doc/html/rfc7517#section-4.4
            throw new UnexpectedValueException('JWK must contain an "alg" parameter');
        }

>             $jwk['alg'] = $defaultAlg;

>         }


        switch ($jwk['kty']) {
            case 'RSA':
                if (!empty($jwk['d'])) {
                    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 === $publicKey) {
                    throw new DomainException(
                        'OpenSSL error: ' . \openssl_error_string()
                    );
                }
                return new Key($publicKey, $jwk['alg']);

>             case 'EC':
            default:
>                 if (isset($jwk['d'])) {
                // Currently only RSA is supported
>                     // The key is actually a private key
                break;
>                     throw new UnexpectedValueException('Key data must be for a public key');
        }
>                 }
    }
> 

>                 if (empty($jwk['crv'])) {
    /**
>                     throw new UnexpectedValueException('crv not set');
     * Create a public key represented in PEM format from RSA modulus and exponent information
>                 }
     *
> 
     * @param string $n The RSA modulus encoded in Base64
>                 if (!isset(self::EC_CURVES[$jwk['crv']])) {
     * @param string $e The RSA exponent encoded in Base64
>                     throw new DomainException('Unrecognised or unsupported EC curve');
     *
>                 }
     * @return string The RSA public key represented in PEM format
> 
     *
>                 if (empty($jwk['x']) || empty($jwk['y'])) {
     * @uses encodeLength
>                     throw new UnexpectedValueException('x and y not set');
     */
>                 }
    private static function createPemFromModulusAndExponent($n, $e)
> 
    {
>                 $publicKey = self::createPemFromCrvAndXYCoordinates($jwk['crv'], $jwk['x'], $jwk['y']);
        $modulus = JWT::urlsafeB64Decode($n);
>                 return new Key($publicKey, $jwk['alg']);


        $publicExponent = JWT::urlsafeB64Decode($e);

> 

>         return null;
        $components = array(
>     }
            'modulus' => \pack('Ca*a*', 2, self::encodeLength(\strlen($modulus)), $modulus),
> 
            'publicExponent' => \pack('Ca*a*', 2, self::encodeLength(\strlen($publicExponent)), $publicExponent)
>     /**
        );
>      * Converts the EC JWK values to pem format.

>      *
        $rsaPublicKey = \pack(
>      * @param   string  $crv The EC curve (only P-256 is supported)
            'Ca*a*a*',
>      * @param   string  $x   The EC x-coordinate
            48,
>      * @param   string  $y   The EC y-coordinate
            self::encodeLength(\strlen($components['modulus']) + \strlen($components['publicExponent'])),
>      *
            $components['modulus'],
>      * @return  string
            $components['publicExponent']
>      */
        );
>     private static function createPemFromCrvAndXYCoordinates(string $crv, string $x, string $y): string

>     {
        // sequence(oid(1.2.840.113549.1.1.1), null)) = rsaEncryption.
>         $pem =
        $rsaOID = \pack('H*', '300d06092a864886f70d0101010500'); // hex version of MA0GCSqGSIb3DQEBAQUA
>             self::encodeDER(
        $rsaPublicKey = \chr(0) . $rsaPublicKey;
>                 self::ASN1_SEQUENCE,
        $rsaPublicKey = \chr(3) . self::encodeLength(\strlen($rsaPublicKey)) . $rsaPublicKey;
>                 self::encodeDER(

>                     self::ASN1_SEQUENCE,
        $rsaPublicKey = \pack(
>                     self::encodeDER(
            'Ca*a*',
>                         self::ASN1_OBJECT_IDENTIFIER,
            48,
>                         self::encodeOID(self::OID)
            self::encodeLength(\strlen($rsaOID . $rsaPublicKey)),
>                     )
            $rsaOID . $rsaPublicKey
>                     . self::encodeDER(
        );
>                         self::ASN1_OBJECT_IDENTIFIER,

>                         self::encodeOID(self::EC_CURVES[$crv])
        $rsaPublicKey = "-----BEGIN PUBLIC KEY-----\r\n" .
>                     )
            \chunk_split(\base64_encode($rsaPublicKey), 64) .
>                 ) .
            '-----END PUBLIC KEY-----';
>                 self::encodeDER(

>                     self::ASN1_BIT_STRING,
        return $rsaPublicKey;
>                     \chr(0x00) . \chr(0x04)
    }
>                     . JWT::urlsafeB64Decode($x)

>                     . JWT::urlsafeB64Decode($y)
    /**
>                 )
     * DER-encode the length
>             );
     *
> 
     * DER supports lengths up to (2**8)**127, however, we'll only support lengths up to (2**8)**4.  See
>         return sprintf(
     * {@link http://itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf#p=13 X.690 paragraph 8.1.3} for more information.
>             "-----BEGIN PUBLIC KEY-----\n%s\n-----END PUBLIC KEY-----\n",
     *
>             wordwrap(base64_encode($pem), 64, "\n", true)
     * @param int $length
>         );



<     private static function createPemFromModulusAndExponent($n, $e)
<     {
<         $modulus = JWT::urlsafeB64Decode($n);
<         $publicExponent = JWT::urlsafeB64Decode($e);



>     private static function createPemFromModulusAndExponent(
>         string $n,
>         string $e
>     ): string {
>         $mod = JWT::urlsafeB64Decode($n);
>         $exp = JWT::urlsafeB64Decode($e);



<         $components = array(
<             'modulus' => \pack('Ca*a*', 2, self::encodeLength(\strlen($modulus)), $modulus),
<             'publicExponent' => \pack('Ca*a*', 2, self::encodeLength(\strlen($publicExponent)), $publicExponent)
<         );



>         $modulus = \pack('Ca*a*', 2, self::encodeLength(\strlen($mod)), $mod);
>         $publicExponent = \pack('Ca*a*', 2, self::encodeLength(\strlen($exp)), $exp);



<             self::encodeLength(\strlen($components['modulus']) + \strlen($components['publicExponent'])),
<             $components['modulus'],
<             $components['publicExponent']



>             self::encodeLength(\strlen($modulus) + \strlen($publicExponent)),
>             $modulus,
>             $publicExponent



<         $rsaPublicKey = "-----BEGIN PUBLIC KEY-----\r\n" .



>         return "-----BEGIN PUBLIC KEY-----\r\n" .



< 
<         return $rsaPublicKey;



<     private static function encodeLength($length)



>     private static function encodeLength(int $length): string



>     }
> 
>     /**
>      * Encodes a value into a DER object.
>      * Also defined in Firebase\JWT\JWT
>      *
>      * @param   int     $type DER tag
>      * @param   string  $value the value to encode
>      * @return  string  the encoded object
>      */
>     private static function encodeDER(int $type, string $value): string
>     {
>         $tag_header = 0;
>         if ($type === self::ASN1_SEQUENCE) {
>             $tag_header |= 0x20;
>         }
> 
>         // Type
>         $der = \chr($tag_header | $type);
> 
>         // Length
>         $der .= \chr(\strlen($value));
> 
>         return $der . $value;
>     }
> 
>     /**
>      * Encodes a string into a DER-encoded OID.
>      *
>      * @param   string $oid the OID string
>      * @return  string the binary DER-encoded OID
>      */
>     private static function encodeOID(string $oid): string
>     {
>         $octets = explode('.', $oid);
> 
>         // Get the first octet
>         $first = (int) array_shift($octets);
>         $second = (int) array_shift($octets);
>         $oid = \chr($first * 40 + $second);
> 
>         // Iterate over subsequent octets
>         foreach ($octets as $octet) {
>             if ($octet == 0) {
>                 $oid .= \chr(0x00);
>                 continue;
>             }
>             $bin = '';
> 
>             while ($octet) {
>                 $bin .= \chr(0x80 | ($octet & 0x7f));
>                 $octet >>= 7;
>             }
>             $bin[0] = $bin[0] & \chr(0x7f);
> 
>             // Convert to big endian if necessary
>             if (pack('V', 65534) == pack('L', 65534)) {
>                 $oid .= strrev($bin);
>             } else {
>                 $oid .= $bin;
>             }
>         }
> 
>         return $oid;