/**
* Detects the format of key data and returns a key object.
*
* The supported formats are:
*
* - `php` - JSON web key formatted as a PHP associative array
* - `json` - JSON web key
* - `pem` - the public or private key encoded in PEM (base64 encoded DER) format
* - `jwe` - Encrypted JSON web key
*
* @param string $data the key data
* @param string $format the format
* @param string $password the password, if the key is password protected
* @param string $alg the algorithm, if the key is password protected
* @return Key the key object
* @throws KeyException if an error occurs in reading the data
*/
public static function create($data, $format = null, $password = null, $alg = 'PBES2-HS256+A128KW')
{
// 1. Detect format
if ($format == null || $format == 'auto') {
if (is_array($data)) {
$format = 'php';
} elseif (json_decode($data, true) != null) {
$format = 'json';
} elseif (substr_count($data, '.') == 5) {
$format = 'jwe';
} elseif (preg_match('/-----([^-:]+)-----/', $data)) {
$format = 'pem';
}
}
if ($format == null || $format == 'auto') {
throw new KeyException('Cannot detect key format');
}
// 2. Decode JSON
if ($format == 'json') {
$json = json_decode($data, true);
if (isset($json['ciphertext'])) {
$format = 'jwe';
} else {
$data = $json;
$format = 'php';
}
}
// 3. JWE
if ($format == 'jwe') {
if ($password == null) {
throw new KeyException('No password for encrypted key');
} else {
$keys = KeySet::createFromSecret($password, 'bin');
try {
$jwe = JWE::decrypt($data, $keys, $alg, isset($data['ciphertext']) ? JWE::JSON_FORMAT : JWE::COMPACT_FORMAT);
$data = json_decode($jwe->getPlaintext());
$format = 'php';
} catch (CryptException $e) {
throw new KeyException('Cannot decrypt key', 0, $e);
}
}
}
// 4. PHP/JSON
if ($format == 'php') {
if ($data != null && isset($data['kty'])) {
if (isset(self::$jwk_kty_map[$data['kty']])) {
return new self::$jwk_kty_map[$data['kty']]($data, 'php');
}
}
}
// 4. PEM
if ($format == 'pem') {
if (preg_match(Key::PEM_PUBLIC, $data, $matches)) {
$der = base64_decode($matches[1]);
if ($der === FALSE) {
throw new KeyException('Cannot read PEM key');
}
$offset = 0;
$offset += ASN1::readDER($der, $offset, $value);
// SEQUENCE
$offset += ASN1::readDER($der, $offset, $value);
// SEQUENCE
$offset += ASN1::readDER($der, $offset, $algorithm);
// OBJECT IDENTIFIER - AlgorithmIdentifier
$oid = ASN1::decodeOID($algorithm);
if (isset(self::$oid_map[$oid])) {
return new self::$oid_map[$oid]($data, 'pem');
}
} else {
foreach (self::$pem_map as $regex => $cls) {
if (preg_match($regex, $data)) {
return new $cls($data, 'pem');
}
}
}
}
// 5. Symmetric key
if ($format == 'base64url' || $format == 'base64' || $format == 'bin') {
return new SymmetricKey($data, $format);
}
return null;
}
protected function getKeySet($password)
{
return \SimpleJWT\Keys\KeySet::createFromSecret($password, 'bin');
}
/**
* Returns a key as a JSON web key.
*
* If `$password` is null or if the key is a public key, an unencrypted JSON
* structure is returned.
*
* If `$password` is not null and the key is a private key, a JWE is created
* using PBES2 key encryption.
*
* @param string $password the password
* @return string the key set
*/
public function toJWK($password = null)
{
$json = json_encode($this->data);
if ($password == null || $this->isPublic()) {
return $json;
}
$keys = KeySet::createFromSecret($password, 'bin');
$headers = array('alg' => 'PBES2-HS256+A128KW', 'enc' => 'A128CBC-HS256', 'cty' => 'jwk+json');
$jwe = new JWE($headers, $json);
return $jwe->encrypt($keys);
}
/**
* Returns a key set as a JSON web key set.
*
* If `$password` is null, an unencrypted JSON structure is returned.
*
* If `$password` is not null, a JWE is created using PBES2 key encryption.
*
* @param string $password the password
* @return string the key set
*/
function toJWKS($password = null)
{
$result = array_map(function ($key) {
return $key->getKeyData();
}, $this->keys);
$json = json_encode(array('keys' => $result));
if ($password == null) {
return $json;
}
$keys = KeySet::createFromSecret($password, 'bin');
$headers = array('alg' => 'PBES2-HS256+A128KW', 'enc' => 'A128CBC-HS256', 'cty' => 'jwk-set+json');
$jwe = new JWE($headers, $json);
return $jwe->encrypt($keys);
}
protected function getKeySet($kek)
{
return \SimpleJWT\Keys\KeySet::createFromSecret($kek, 'bin');
}
