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<?php
namespace LP\Firebase\JWT;
use \DomainException;
use \InvalidArgumentException;
use \UnexpectedValueException;
use \DateTime;
/**
* JSON Web Token implementation, based on this spec:
* https://tools.ietf.org/html/rfc7519
*
* PHP version 5
*
* @category Authentication
* @package Authentication_JWT
* @author Neuman Vong <neuman@twilio.com>
* @author Anant Narayanan <anant@php.net>
* @license http://opensource.org/licenses/BSD-3-Clause 3-clause BSD
* @link https://github.com/firebase/php-jwt
*/
class JWT {
/**
* When checking nbf, iat or expiration times,
* we want to provide some extra leeway time to
* account for clock skew.
*/
public static $leeway = 0;
/**
* Allow the current timestamp to be specified.
* Useful for fixing a value within unit testing.
*
* Will default to PHP time() value if null.
*/
public static $timestamp = null;
public static $supported_algs = array(
'HS256' => array( 'hash_hmac', 'SHA256' ),
'HS512' => array( 'hash_hmac', 'SHA512' ),
'HS384' => array( 'hash_hmac', 'SHA384' ),
'RS256' => array( 'openssl', 'SHA256' ),
'RS384' => array( 'openssl', 'SHA384' ),
'RS512' => array( 'openssl', 'SHA512' ),
);
/**
* Decodes a JWT string into a PHP object.
*
* @param string $jwt The JWT
* @param string|array $key The key, or map of keys.
* If the algorithm used is asymmetric, this is the public key
* @param array $allowed_algs List of supported verification algorithms
* Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'
*
* @return object The JWT's payload as a PHP object
*
* @throws UnexpectedValueException Provided JWT was invalid
* @throws SignatureInvalidException Provided JWT was invalid because the signature verification failed
* @throws BeforeValidException Provided JWT is trying to be used before it's eligible as defined by 'nbf'
* @throws BeforeValidException Provided JWT is trying to be used before it's been created as defined by 'iat'
* @throws ExpiredException Provided JWT has since expired, as defined by the 'exp' claim
*
* @uses jsonDecode
* @uses urlsafeB64Decode
*/
public static function decode( $jwt, $key, array $allowed_algs = array() ) {
$timestamp = is_null( static::$timestamp ) ? time() : static::$timestamp;
if ( empty( $key ) ) {
throw new InvalidArgumentException( 'Key may not be empty' );
}
$tks = explode( '.', $jwt );
if ( count( $tks ) != 3 ) {
throw new UnexpectedValueException( 'Wrong number of segments' );
}
list($headb64, $bodyb64, $cryptob64) = $tks;
if ( null === ( $header = static::jsonDecode( static::urlsafeB64Decode( $headb64 ) ) ) ) {
throw new UnexpectedValueException( 'Invalid header encoding' );
}
if ( null === $payload = static::jsonDecode( static::urlsafeB64Decode( $bodyb64 ) ) ) {
throw new UnexpectedValueException( 'Invalid claims encoding' );
}
if ( false === ( $sig = static::urlsafeB64Decode( $cryptob64 ) ) ) {
throw new UnexpectedValueException( 'Invalid signature encoding' );
}
if ( empty( $header->alg ) ) {
throw new UnexpectedValueException( 'Empty algorithm' );
}
if ( empty( static::$supported_algs[ $header->alg ] ) ) {
throw new UnexpectedValueException( 'Algorithm not supported' );
}
if ( ! in_array( $header->alg, $allowed_algs ) ) {
throw new UnexpectedValueException( 'Algorithm not allowed' );
}
if ( is_array( $key ) || $key instanceof \ArrayAccess ) {
if ( isset( $header->kid ) ) {
if ( ! isset( $key[ $header->kid ] ) ) {
throw new UnexpectedValueException( '"kid" invalid, unable to lookup correct key' );
}
$key = $key[ $header->kid ];
} else {
throw new UnexpectedValueException( '"kid" empty, unable to lookup correct key' );
}
}
// Check the signature
if ( ! static::verify( "$headb64.$bodyb64", $sig, $key, $header->alg ) ) {
throw new SignatureInvalidException( 'Signature verification failed' );
}
// Check if the nbf if it is defined. This is the time that the
// token can actually be used. If it's not yet that time, abort.
if ( isset( $payload->nbf ) && $payload->nbf > ( $timestamp + static::$leeway ) ) {
throw new BeforeValidException(
'Cannot handle token prior to ' . date( DateTime::ISO8601, $payload->nbf )
);
}
// Check that this token has been created before 'now'. This prevents
// using tokens that have been created for later use (and haven't
// correctly used the nbf claim).
if ( isset( $payload->iat ) && $payload->iat > ( $timestamp + static::$leeway ) ) {
throw new BeforeValidException(
'Cannot handle token prior to ' . date( DateTime::ISO8601, $payload->iat )
);
}
// Check if this token has expired.
if ( isset( $payload->exp ) && ( $timestamp - static::$leeway ) >= $payload->exp ) {
throw new ExpiredException( 'Expired token' );
}
return $payload;
}
/**
* Converts and signs a PHP object or array into a JWT string.
*
* @param object|array $payload PHP object or array
* @param string $key The secret key.
* If the algorithm used is asymmetric, this is the private key
* @param string $alg The signing algorithm.
* Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'
* @param mixed $keyId
* @param array $head An array with header elements to attach
*
* @return string A signed JWT
*
* @uses jsonEncode
* @uses urlsafeB64Encode
*/
public static function encode( $payload, $key, $alg = 'HS256', $keyId = null, $head = null ) {
$header = array(
'typ' => 'JWT',
'alg' => $alg,
);
if ( $keyId !== null ) {
$header['kid'] = $keyId;
}
if ( isset( $head ) && is_array( $head ) ) {
$header = array_merge( $head, $header );
}
$segments = array();
$segments[] = static::urlsafeB64Encode( static::jsonEncode( $header ) );
$segments[] = static::urlsafeB64Encode( static::jsonEncode( $payload ) );
$signing_input = implode( '.', $segments );
$signature = static::sign( $signing_input, $key, $alg );
$segments[] = static::urlsafeB64Encode( $signature );
return implode( '.', $segments );
}
/**
* Sign a string with a given key and algorithm.
*
* @param string $msg The message to sign
* @param string|resource $key The secret key
* @param string $alg The signing algorithm.
* Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'
*
* @return string An encrypted message
*
* @throws DomainException Unsupported algorithm was specified
*/
public static function sign( $msg, $key, $alg = 'HS256' ) {
if ( empty( static::$supported_algs[ $alg ] ) ) {
throw new DomainException( 'Algorithm not supported' );
}
list($function, $algorithm) = static::$supported_algs[ $alg ];
switch ( $function ) {
case 'hash_hmac':
return hash_hmac( $algorithm, $msg, $key, true );
case 'openssl':
$signature = '';
$success = openssl_sign( $msg, $signature, $key, $algorithm );
if ( ! $success ) {
throw new DomainException( 'OpenSSL unable to sign data' );
} else {
return $signature;
}
}
}
/**
* Verify a signature with the message, key and method. Not all methods
* are symmetric, so we must have a separate verify and sign method.
*
* @param string $msg The original message (header and body)
* @param string $signature The original signature
* @param string|resource $key For HS*, a string key works. for RS*, must be a resource of an openssl public key
* @param string $alg The algorithm
*
* @return bool
*
* @throws DomainException Invalid Algorithm or OpenSSL failure
*/
private static function verify( $msg, $signature, $key, $alg ) {
if ( empty( static::$supported_algs[ $alg ] ) ) {
throw new DomainException( 'Algorithm not supported' );
}
list($function, $algorithm) = static::$supported_algs[ $alg ];
switch ( $function ) {
case 'openssl':
$success = openssl_verify( $msg, $signature, $key, $algorithm );
if ( $success === 1 ) {
return true;
} elseif ( $success === 0 ) {
return false;
}
// returns 1 on success, 0 on failure, -1 on error.
throw new DomainException(
'OpenSSL error: ' . openssl_error_string()
);
case 'hash_hmac':
default:
$hash = hash_hmac( $algorithm, $msg, $key, true );
if ( function_exists( 'hash_equals' ) ) {
return hash_equals( $signature, $hash );
}
$len = min( static::safeStrlen( $signature ), static::safeStrlen( $hash ) );
$status = 0;
for ( $i = 0; $i < $len; $i++ ) {
$status |= ( ord( $signature[ $i ] ) ^ ord( $hash[ $i ] ) );
}
$status |= ( static::safeStrlen( $signature ) ^ static::safeStrlen( $hash ) );
return ( $status === 0 );
}
}
/**
* Decode a JSON string into a PHP object.
*
* @param string $input JSON string
*
* @return object Object representation of JSON string
*
* @throws DomainException Provided string was invalid JSON
*/
public static function jsonDecode( $input ) {
if ( version_compare( PHP_VERSION, '5.4.0', '>=' ) && ! ( defined( 'JSON_C_VERSION' ) && PHP_INT_SIZE > 4 ) ) {
/** In PHP >=5.4.0, json_decode() accepts an options parameter, that allows you
* to specify that large ints (like Steam Transaction IDs) should be treated as
* strings, rather than the PHP default behaviour of converting them to floats.
*/
$obj = json_decode( $input, false, 512, JSON_BIGINT_AS_STRING );
} else {
/** Not all servers will support that, however, so for older versions we must
* manually detect large ints in the JSON string and quote them (thus converting
*them to strings) before decoding, hence the preg_replace() call.
*/
$max_int_length = strlen( (string) PHP_INT_MAX ) - 1;
$json_without_bigints = preg_replace( '/:\s*(-?\d{' . $max_int_length . ',})/', ': "$1"', $input );
$obj = json_decode( $json_without_bigints );
}
if ( function_exists( 'json_last_error' ) && $errno = json_last_error() ) {
static::handleJsonError( $errno );
} elseif ( $obj === null && $input !== 'null' ) {
throw new DomainException( 'Null result with non-null input' );
}
return $obj;
}
/**
* Encode a PHP object into a JSON string.
*
* @param object|array $input A PHP object or array
*
* @return string JSON representation of the PHP object or array
*
* @throws DomainException Provided object could not be encoded to valid JSON
*/
public static function jsonEncode( $input ) {
$json = json_encode( $input );
if ( function_exists( 'json_last_error' ) && $errno = json_last_error() ) {
static::handleJsonError( $errno );
} elseif ( $json === 'null' && $input !== null ) {
throw new DomainException( 'Null result with non-null input' );
}
return $json;
}
/**
* Decode a string with URL-safe Base64.
*
* @param string $input A Base64 encoded string
*
* @return string A decoded string
*/
public static function urlsafeB64Decode( $input ) {
$remainder = strlen( $input ) % 4;
if ( $remainder ) {
$padlen = 4 - $remainder;
$input .= str_repeat( '=', $padlen );
}
return base64_decode( strtr( $input, '-_', '+/' ) );
}
/**
* Encode a string with URL-safe Base64.
*
* @param string $input The string you want encoded
*
* @return string The base64 encode of what you passed in
*/
public static function urlsafeB64Encode( $input ) {
return str_replace( '=', '', strtr( base64_encode( $input ), '+/', '-_' ) );
}
/**
* Helper method to create a JSON error.
*
* @param int $errno An error number from json_last_error()
*
* @return void
*/
private static function handleJsonError( $errno ) {
$messages = array(
JSON_ERROR_DEPTH => 'Maximum stack depth exceeded',
JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON',
JSON_ERROR_CTRL_CHAR => 'Unexpected control character found',
JSON_ERROR_SYNTAX => 'Syntax error, malformed JSON',
JSON_ERROR_UTF8 => 'Malformed UTF-8 characters', //PHP >= 5.3.3
);
throw new DomainException(
isset( $messages[ $errno ] )
? $messages[ $errno ]
: 'Unknown JSON error: ' . $errno
);
}
/**
* Get the number of bytes in cryptographic strings.
*
* @param string
*
* @return int
*/
private static function safeStrlen( $str ) {
if ( function_exists( 'mb_strlen' ) ) {
return mb_strlen( $str, '8bit' );
}
return strlen( $str );
}
}