. */ if (!defined('GNUSOCIAL')) { exit(1); } /** * Diaspora federation protocol plugin for GNU Social * * Depends on: * - OStatus plugin * - WebFinger plugin * * @package ProtocolDiasporaPlugin * @maintainer Mikael Nordfeldth */ // Depends on OStatus of course. addPlugin('OStatus'); //Since Magicsig hasn't loaded yet require_once('Crypt/AES.php'); class DiasporaPlugin extends Plugin { const REL_SEED_LOCATION = 'http://joindiaspora.com/seed_location'; const REL_GUID = 'http://joindiaspora.com/guid'; const REL_PUBLIC_KEY = 'diaspora-public-key'; public function onEndAttachPubkeyToUserXRD(Magicsig $magicsig, XML_XRD $xrd, Profile $target) { // So far we've only handled RSA keys, but it can change in the future, // so be prepared. And remember to change the statically assigned type attribute below! assert($magicsig->publicKey instanceof Crypt_RSA); $xrd->links[] = new XML_XRD_Element_Link(self::REL_PUBLIC_KEY, base64_encode($magicsig->exportPublicKey()), 'RSA'); // Instead of choosing a random string, we calculate our GUID from the public key // by fingerprint through a sha256 hash. $xrd->links[] = new XML_XRD_Element_Link(self::REL_GUID, strtolower($magicsig->toFingerprint())); } public function onMagicsigPublicKeyFromXRD(XML_XRD $xrd, &$pubkey) { // See if we have a Diaspora public key in the XRD response $link = $xrd->get(self::REL_PUBLIC_KEY, 'RSA'); if (!is_null($link)) { // If we do, decode it so we have the PKCS1 format (starts with -----BEGIN PUBLIC KEY-----) $pkcs1 = base64_decode($link->href); $magicsig = new Magicsig(Magicsig::DEFAULT_SIGALG); // Diaspora uses RSA-SHA256 (we do too) try { // Try to load the public key so we can get it in the standard Magic signature format $magicsig->loadPublicKeyPKCS1($pkcs1); // We found it and will now store it in $pubkey in a proper format! // This is how it would be found in a well implemented XRD according to the standard. $pubkey = 'data:application/magic-public-key,'.$magicsig->toString(); common_debug('magic-public-key found in diaspora-public-key: '.$pubkey); return false; } catch (ServerException $e) { common_log(LOG_WARNING, $e->getMessage()); } } return true; } public function onPluginVersion(array &$versions) { $versions[] = array('name' => 'Diaspora', 'version' => '0.1', 'author' => 'Mikael Nordfeldth', 'homepage' => 'https://gnu.io/social', // TRANS: Plugin description. 'rawdescription' => _m('Follow people across social networks that implement '. 'the Diaspora federation protocol.')); return true; } public function onStartMagicEnvelopeToXML(MagicEnvelope $magic_env, XMLStringer $xs, $flavour=null, Profile $target=null) { // Since Diaspora doesn't use a separate namespace for their "extended" // salmon slap, we'll have to resort to this workaround hack. if ($flavour !== 'diaspora') { return true; } // WARNING: This changes the $magic_env contents! Be aware of it. /** * https://wiki.diasporafoundation.org/Federation_protocol_overview * * Constructing the encryption header */ // For some reason it's supposed to be inside an $xs->elementStart('entry', array('xmlns'=>'http://www.w3.org/2005/Atom')); /** * Choose an AES key and initialization vector, suitable for the * aes-256-cbc cipher. I shall refer to this as the “inner key” * and the “inner initialization vector (iv)”. */ $inner_key = new Crypt_AES(CRYPT_AES_MODE_CBC); $inner_key->setKeyLength(256); // set length to 256 bits (could be calculated, but let's be sure) $inner_key->setKey(common_random_rawstr(32)); // 32 bytes from a (pseudo) random source $inner_key->setIV(common_random_rawstr(16)); // 16 bytes is the block length /** * Construct the following XML snippet: * * ((base64-encoded inner iv)) * ((base64-encoded inner key)) * * Alice Exampleman * acct:user@sender.example * * */ $decrypted_header = sprintf('%1$s%2$s%3$s', base64_encode($inner_key->iv), base64_encode($inner_key->key), $magic_env->getActor()->getAcctUri()); /** * Construct another AES key and initialization vector suitable * for the aes-256-cbc cipher. I shall refer to this as the * “outer key” and the “outer initialization vector (iv)”. */ $outer_key = new Crypt_AES(CRYPT_AES_MODE_CBC); $outer_key->setKeyLength(256); // set length to 256 bits (could be calculated, but let's be sure) $outer_key->setKey(common_random_rawstr(32)); // 32 bytes from a (pseudo) random source $outer_key->setIV(common_random_rawstr(16)); // 16 bytes is the block length /** * Encrypt your XML snippet using the “outer key” * and “outer iv” (using the aes-256-cbc cipher). This encrypted * blob shall be referred to as “the ciphertext”. */ $ciphertext = $outer_key->encrypt($decrypted_header); /** * Construct the following JSON object, which shall be referred to * as “the outer aes key bundle”: * { * "iv": ((base64-encoded AES outer iv)), * "key": ((base64-encoded AES outer key)) * } */ $outer_bundle = json_encode(array( 'iv' => base64_encode($outer_key->iv), 'key' => base64_encode($outer_key->key), )); /** * Encrypt the “outer aes key bundle” with Bob’s RSA public key. * I shall refer to this as the “encrypted outer aes key bundle”. */ common_debug('Diaspora creating "outer aes key bundle", will require magic-public-key'); $key_fetcher = new MagicEnvelope(); $remote_keys = $key_fetcher->getKeyPair($target, true); // actually just gets the public key $enc_outer = $remote_keys->publicKey->encrypt($outer_bundle); /** * Construct the following JSON object, which I shall refer to as * the “encrypted header json object”: * { * "aes_key": ((base64-encoded encrypted outer aes key bundle)), * "ciphertext": ((base64-encoded ciphertextm from above)) * } */ $enc_header = json_encode(array( 'aes_key' => base64_encode($enc_outer), 'ciphertext' => base64_encode($ciphertext), )); /** * Construct the xml snippet: * ((base64-encoded encrypted header json object)) */ $xs->element('encrypted_header', null, base64_encode($enc_header)); /** * In order to prepare the payload message for inclusion in your * salmon slap, you will: * * 1. Encrypt the payload message using the aes-256-cbc cipher and * the “inner encryption key” and “inner encryption iv” you * chose earlier. * 2. Base64-encode the encrypted payload message. */ $payload = $inner_key->encrypt($magic_env->getData()); //FIXME: This means we don't actually put an in the payload, // since Diaspora has its own update method! Silly me. Read up on: // https://wiki.diasporafoundation.org/Federation_Message_Semantics $magic_env->signMessage(base64_encode($payload), 'application/xml'); // Since we have to change the content of me:data we'll just write the // whole thing from scratch. We _could_ otherwise have just manipulated // that element and added the encrypted_header in the EndMagicEnvelopeToXML event. $xs->elementStart('me:env', array('xmlns:me' => MagicEnvelope::NS)); $xs->element('me:data', array('type' => $magic_env->getDataType()), $magic_env->getData()); $xs->element('me:encoding', null, $magic_env->getEncoding()); $xs->element('me:alg', null, $magic_env->getSignatureAlgorithm()); $xs->element('me:sig', null, $magic_env->getSignature()); $xs->elementEnd('me:env'); $xs->elementEnd('entry'); return false; } public function onSalmonSlap($endpoint_uri, MagicEnvelope $magic_env, Profile $target=null) { $envxml = $magic_env->toXML($target, 'diaspora'); // Diaspora wants another POST format (base64url-encoded POST variable 'xml') $headers = array('Content-Type: application/x-www-form-urlencoded'); // Another way to distinguish Diaspora from GNU social is that a POST with // $headers=array('Content-Type: application/magic-envelope+xml') would return // HTTP status code 422 Unprocessable Entity, at least as of 2015-10-04. try { $client = new HTTPClient(); $client->setBody('xml=' . Magicsig::base64_url_encode($envxml)); $response = $client->post($endpoint_uri, $headers); } catch (HTTP_Request2_Exception $e) { common_log(LOG_ERR, "Diaspora-flavoured Salmon post to $endpoint_uri failed: " . $e->getMessage()); return false; } // 200 OK is the best response // 202 Accepted is what we get from Diaspora for example if (!in_array($response->getStatus(), array(200, 202))) { common_log(LOG_ERR, sprintf('Salmon (from profile %d) endpoint %s returned status %s: %s', $magic_env->getActor()->getID(), $endpoint_uri, $response->getStatus(), $response->getBody())); return true; } // Success! return false; } }