/**
* @param AppStoreInterface $appStore
* @param string $blob
* @return array
* Decoded data.
*/
public static function decode($appStore, $blob)
{
$parts = explode(Constants::PROTOCOL_DELIM, $blob, 5);
if (count($parts) != 5) {
throw new InvalidMessageException('Invalid message: insufficient parameters');
}
list($wireProt, $wireAppId, $rsaCiphertextB64, $signature, $body) = $parts;
if ($wireProt !== self::NAME) {
throw new InvalidMessageException('Invalid message: wrong protocol name');
}
$appPrivKey = $appStore->getPrivateKey($wireAppId);
if (!$appPrivKey) {
throw new InvalidMessageException('Received message intended for unknown app.');
}
$rsaCiphertext = base64_decode($rsaCiphertextB64);
if (strlen($rsaCiphertext) !== Constants::RSA_MSG_BYTES) {
throw new InvalidMessageException("RSA ciphertext has incorrect length");
}
$secret = UserError::adapt('Civi\\Cxn\\Rpc\\Exception\\InvalidMessageException', function () use($rsaCiphertext, $appPrivKey) {
return RegistrationMessage::getRsa($appPrivKey, 'private')->decrypt($rsaCiphertext);
});
if (empty($secret)) {
throw new InvalidMessageException("Invalid message: decryption produced empty secret");
}
$plaintext = AesHelper::authenticateThenDecrypt($secret, $body, $signature);
return json_decode($plaintext, TRUE);
}
/**
* @param CertificateValidatorInterface|NULL $certValidator
* @param string $blob
* @return AppMetasMessage
* Validated message.
* @throws InvalidMessageException
*/
public static function decode($certValidator, $blob)
{
$parts = explode(Constants::PROTOCOL_DELIM, $blob, 4);
if (count($parts) != 4) {
throw new InvalidMessageException('Invalid message: insufficient parameters');
}
list($wireProt, $wireCert, $wireSig, $wireEnvelope) = $parts;
if ($wireProt != self::NAME) {
throw new InvalidMessageException('Invalid message: wrong protocol name');
}
if ($certValidator !== NULL) {
$certValidator->validateCert($wireCert);
$wireCertX509 = new \File_X509();
$wireCertX509->loadX509($wireCert);
$cn = $wireCertX509->getDNProp('CN');
if (count($cn) != 1 || $cn[0] != Constants::OFFICIAL_APPMETAS_CN) {
throw new InvalidMessageException('Invalid message: signed by unauthorized party');
}
$isValid = UserError::adapt('Civi\\Cxn\\Rpc\\Exception\\InvalidMessageException', function () use($wireCertX509, $wireEnvelope, $wireSig) {
return AppMetasMessage::getRsaFromCert($wireCertX509)->verify($wireEnvelope, base64_decode($wireSig));
});
if (!$isValid) {
throw new InvalidMessageException("Invalid message: incorrect signature");
}
}
$envelope = json_decode($wireEnvelope, TRUE);
if (empty($envelope)) {
throw new InvalidMessageException("Invalid message: malformed envelope");
}
if (Time::getTime() > $envelope['ttl']) {
throw new InvalidMessageException("Invalid message: expired");
}
return new AppMetasMessage($wireCert, NULL, json_decode($envelope['r'], TRUE));
}
/**
* Validate the signature and date of the message, then
* decrypt it.
*
* @param string $secret
* @param string $body
* @param string $signature
* @return string
* Plain text.
* @throws InvalidMessageException
*/
public static function authenticateThenDecrypt($secret, $body, $signature)
{
$keys = self::deriveAesKeys($secret);
$localHmac = hash_hmac('sha256', $body, $keys['auth']);
if (!self::hash_compare($signature, $localHmac)) {
throw new InvalidMessageException("Incorrect hash");
}
list($jsonEnvelope, $jsonEncrypted) = explode(Constants::PROTOCOL_DELIM, $body, 2);
if (strlen($jsonEnvelope) > Constants::MAX_ENVELOPE_BYTES) {
throw new InvalidMessageException("Oversized envelope");
}
$envelope = json_decode($jsonEnvelope, TRUE);
if (!$envelope) {
throw new InvalidMessageException("Malformed envelope");
}
if (!is_numeric($envelope['ttl']) || Time::getTime() > $envelope['ttl']) {
throw new InvalidMessageException("Invalid TTL");
}
if (!is_string($envelope['iv']) || strlen($envelope['iv']) !== Constants::AES_BYTES * 2 || !preg_match('/^[a-f0-9]+$/', $envelope['iv'])) {
// AES_BYTES (32) ==> bin2hex ==> 2 hex digits (4-bit) per byte (8-bit)
throw new InvalidMessageException("Malformed initialization vector");
}
$jsonPlaintext = UserError::adapt('Civi\\Cxn\\Rpc\\Exception\\InvalidMessageException', function () use($jsonEncrypted, $envelope, $keys) {
$cipher = new \Crypt_AES(CRYPT_AES_MODE_CBC);
$cipher->setKeyLength(Constants::AES_BYTES);
$cipher->setKey($keys['enc']);
$cipher->setIV(BinHex::hex2bin($envelope['iv']));
return $cipher->decrypt($jsonEncrypted);
});
return $jsonPlaintext;
}
