SimpleJWT

SimpleJWT is a simple JSON web token library written in PHP.

Features

• JSON web token RFC7519, JSON web signatures RFC7515 and JSON web encryption RFC7516
• JSON web keys RFC7517
• Signature algorithms
  • HMAC family (HS256, HS384, HS512)
  • RSA family (RS256, RS384, RS512)
  • ECDSA family (ES256, ES384, ES512)
• Key management algorithms
  • Key agreement or direct encryption
  • RSAES-PKCS1-v1_5 (RSA1_5)
  • RSAES with OAEP (RSA-OAEP, RSA-OAEP-256)
  • AES key wrap (A128KW, A192KW, A256KW)
  • PBES2 (PBES2-HS256+A128KW, PBES2-HS384+A192KW, PBES2-HS512+A256KW)
• Content encryption algorithms
  • AES_CBC_HMAC_SHA2 family (A128CBC-HS256, A192CBC-HS384, A256CBC-HS512)
  • AES GCM family (A128GCM, A192GCM, A256GCM) - requires PHP 7.1 or later

Requirements

• PHP:
  • PHP 7.1.0 or later; or
  • PHP 5.4.0 or later
• hash extension
• openssl extension

Installation

You can install via Composer.

composer require kelvinmo/simplejwt

Usage

Key set

Keys used to sign or verify a JWT must firstly be added to a KeySet. You can add keys in the following ways:

1. By loading a JSON object formatted as a JWK Set object as per RFC7517:

$set = new SimpleJWT\Keys\KeySet();
$set->load(file_get_contents('private.json'));

2. By adding a key manually:

$set = new SimpleJWT\Keys\KeySet();

// JWK format
$key = new SimpleJWT\Keys\RSAKey(file_get_contents('jwk.json'), 'json');

// PEM format - note raw key only, no X.509 certificates
$key = new SimpleJWT\Keys\RSAKey(file_get_contents('rsa.pem'), 'pem');

$set->add($key);

3. For a secret used in HMAC signatures, directly:

$set = SimpleJWT\Keys\KeySet::createFromSecret('secret123');

// The above is a shortcut for the following:
$set = new SimpleJWT\Keys\KeySet();
$key = new SimpleJWT\Keys\SymmetricKey('secret123', 'bin');
$set->add($key);

Creating a JWT

To create a JWT, set up the desired headers and claims as separate arrays, then create a JWT object:

// Note $headers['alg'] is required
$headers = ['alg' => 'HS256', 'typ' => 'JWT'];
$claims = ['iss' => 'me', 'exp' => 1234567];
$jwt = new SimpleJWT\JWT($headers, $claims);

The JWT can then be signed and encoded:

try {
    print $jwt->encode($set);
} catch (\RuntimeException $e) {

}

By default, SimpleJWT will automatically include a kid (Key ID) header and a iat (Issued At) claim in all JWTs. If the key used to sign the JWT does not have a kid assigned (e.g. if it is imported from a PEM file), a kid is generated. You can disable this behaviour by specifying $auto_complete to false when calling SimpleJWT\JWT::encode().

Verifying a JWT

To consume and verify a JWT, use the decode function. Note that you will need to supply the expected alg parameter that has been previously agreed out-of-band.

try {
    $jwt = SimpleJWT\JWT::decode('abc.def.ghigjghr', $set, 'HS256');
} catch (SimpleJWT\InvalidTokenException $e) {

}

print $jwt->getHeader('alg');
print $jwt->getClaim('sub');

Deserialising a JWT

You can also deserialise a JWT without verifying it using the deserialise function. Note that you should not trust the contents of the data contained in a JWT without verifying them.

try {
    $result = SimpleJWT\JWT::deserialise('abc.def.ghigjghr');
} catch (SimpleJWT\InvalidTokenException $e) {

}

print $result['claims']['sub'];
print $result['signatures'][0]['headers']['alg'];
print $result['signatures'][0]['signing_input'];  // abc.def
print $result['signatures'][0]['signature'];      // ghigjghr
// Additional indices under $result['signatures'] if the JWT has more than
// one signature

Creating a JWE

To create a JWE, set up the desired header array and plaintext, then create a JWE object:

// Note $headers['alg'] and $headers['enc'] are required
$headers = ['alg' => 'PBES2-HS256+A128KW', 'enc' => 'A128CBC-HS256'];
$plaintext = 'This is the plaintext I want to encrypt.';
$jwt = new SimpleJWT\JWE($headers, $plaintext);

The JWE can then be encrypted:

try {
    print $jwt->encrypt($set);
} catch (\RuntimeException $e) {

}

Decrypting a JWE

To decrypt a JWE, use the decrypt function:

try {
    $jwt = SimpleJWT\JWE::decrypt('abc.def.ghi.klm.nop', $set, 'PBES2-HS256+A128KW');
} catch (SimpleJWT\InvalidTokenException $e) {

}

print $jwt->getHeader('alg');
print $jwt->getPlaintext();

Licence

BSD 3 clause