3 * GNU Social - a federating social network
4 * Copyright (C) 2015, Free Software Foundation, Inc.
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU Affero General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU Affero General Public License for more details.
16 * You should have received a copy of the GNU Affero General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
20 if (!defined('GNUSOCIAL')) { exit(1); }
23 * Diaspora federation protocol plugin for GNU Social
29 * @package ProtocolDiasporaPlugin
30 * @maintainer Mikael Nordfeldth <mmn@hethane.se>
33 // Depends on OStatus of course.
36 //Since Magicsig hasn't loaded yet
37 require_once('Crypt/AES.php');
39 class DiasporaPlugin extends Plugin
41 const REL_SEED_LOCATION = 'http://joindiaspora.com/seed_location';
42 const REL_GUID = 'http://joindiaspora.com/guid';
43 const REL_PUBLIC_KEY = 'diaspora-public-key';
45 public function onEndAttachPubkeyToUserXRD(Magicsig $magicsig, XML_XRD $xrd, Profile $target)
47 // So far we've only handled RSA keys, but it can change in the future,
48 // so be prepared. And remember to change the statically assigned type attribute below!
49 assert($magicsig->publicKey instanceof Crypt_RSA);
50 $xrd->links[] = new XML_XRD_Element_Link(self::REL_PUBLIC_KEY,
51 base64_encode($magicsig->exportPublicKey()), 'RSA');
53 // Instead of choosing a random string, we calculate our GUID from the public key
54 // by fingerprint through a sha256 hash.
55 $xrd->links[] = new XML_XRD_Element_Link(self::REL_GUID,
56 strtolower($magicsig->toFingerprint()));
59 public function onMagicsigPublicKeyFromXRD(XML_XRD $xrd, &$pubkey)
61 // See if we have a Diaspora public key in the XRD response
62 $link = $xrd->get(self::REL_PUBLIC_KEY, 'RSA');
63 if (!is_null($link)) {
64 // If we do, decode it so we have the PKCS1 format (starts with -----BEGIN PUBLIC KEY-----)
65 $pkcs1 = base64_decode($link->href);
66 $magicsig = new Magicsig(Magicsig::DEFAULT_SIGALG); // Diaspora uses RSA-SHA256 (we do too)
68 // Try to load the public key so we can get it in the standard Magic signature format
69 $magicsig->loadPublicKeyPKCS1($pkcs1);
70 // We found it and will now store it in $pubkey in a proper format!
71 // This is how it would be found in a well implemented XRD according to the standard.
72 $pubkey = 'data:application/magic-public-key,'.$magicsig->toString();
73 common_debug('magic-public-key found in diaspora-public-key: '.$pubkey);
75 } catch (ServerException $e) {
76 common_log(LOG_WARNING, $e->getMessage());
82 public function onPluginVersion(array &$versions)
84 $versions[] = array('name' => 'Diaspora',
86 'author' => 'Mikael Nordfeldth',
87 'homepage' => 'https://gnu.io/social',
88 // TRANS: Plugin description.
89 'rawdescription' => _m('Follow people across social networks that implement '.
90 'the <a href="https://diasporafoundation.org/">Diaspora</a> federation protocol.'));
95 public function onStartMagicEnvelopeToXML(MagicEnvelope $magic_env, XMLStringer $xs, $flavour=null, Profile $target=null)
97 // Since Diaspora doesn't use a separate namespace for their "extended"
98 // salmon slap, we'll have to resort to this workaround hack.
99 if ($flavour !== 'diaspora') {
103 // WARNING: This changes the $magic_env contents! Be aware of it.
106 * https://wiki.diasporafoundation.org/Federation_protocol_overview
108 * Constructing the encryption header
111 // For some reason it's supposed to be inside an <atom:entry>
112 $xs->elementStart('entry', array('xmlns'=>'http://www.w3.org/2005/Atom'));
115 * Choose an AES key and initialization vector, suitable for the
116 * aes-256-cbc cipher. I shall refer to this as the “inner key”
117 * and the “inner initialization vector (iv)”.
119 $inner_key = new Crypt_AES(CRYPT_AES_MODE_CBC);
120 $inner_key->setKeyLength(256); // set length to 256 bits (could be calculated, but let's be sure)
121 $inner_key->setKey(common_random_rawstr(32)); // 32 bytes from a (pseudo) random source
122 $inner_key->setIV(common_random_rawstr(16)); // 16 bytes is the block length
125 * Construct the following XML snippet:
127 * <iv>((base64-encoded inner iv))</iv>
128 * <aes_key>((base64-encoded inner key))</aes_key>
130 * <name>Alice Exampleman</name>
131 * <uri>acct:user@sender.example</uri>
133 * </decrypted_header>
135 $decrypted_header = sprintf('<decrypted_header><iv>%1$s</iv><aes_key>%2$s</aes_key><author_id>%3$s</author_id></decrypted_header>',
136 base64_encode($inner_key->iv),
137 base64_encode($inner_key->key),
138 $magic_env->getActor()->getAcctUri());
141 * Construct another AES key and initialization vector suitable
142 * for the aes-256-cbc cipher. I shall refer to this as the
143 * “outer key” and the “outer initialization vector (iv)”.
145 $outer_key = new Crypt_AES(CRYPT_AES_MODE_CBC);
146 $outer_key->setKeyLength(256); // set length to 256 bits (could be calculated, but let's be sure)
147 $outer_key->setKey(common_random_rawstr(32)); // 32 bytes from a (pseudo) random source
148 $outer_key->setIV(common_random_rawstr(16)); // 16 bytes is the block length
151 * Encrypt your <decrypted_header> XML snippet using the “outer key”
152 * and “outer iv” (using the aes-256-cbc cipher). This encrypted
153 * blob shall be referred to as “the ciphertext”.
155 $ciphertext = $outer_key->encrypt($decrypted_header);
158 * Construct the following JSON object, which shall be referred to
159 * as “the outer aes key bundle”:
161 * "iv": ((base64-encoded AES outer iv)),
162 * "key": ((base64-encoded AES outer key))
165 $outer_bundle = json_encode(array(
166 'iv' => base64_encode($outer_key->iv),
167 'key' => base64_encode($outer_key->key),
170 * Encrypt the “outer aes key bundle” with Bob’s RSA public key.
171 * I shall refer to this as the “encrypted outer aes key bundle”.
173 common_debug('Diaspora creating "outer aes key bundle", will require magic-public-key');
174 $key_fetcher = new MagicEnvelope();
175 $remote_keys = $key_fetcher->getKeyPair($target, true); // actually just gets the public key
176 $enc_outer = $remote_keys->publicKey->encrypt($outer_bundle);
179 * Construct the following JSON object, which I shall refer to as
180 * the “encrypted header json object”:
182 * "aes_key": ((base64-encoded encrypted outer aes key bundle)),
183 * "ciphertext": ((base64-encoded ciphertextm from above))
186 $enc_header = json_encode(array(
187 'aes_key' => base64_encode($enc_outer),
188 'ciphertext' => base64_encode($ciphertext),
192 * Construct the xml snippet:
193 * <encrypted_header>((base64-encoded encrypted header json object))</encrypted_header>
195 $xs->element('encrypted_header', null, base64_encode($enc_header));
198 * In order to prepare the payload message for inclusion in your
199 * salmon slap, you will:
201 * 1. Encrypt the payload message using the aes-256-cbc cipher and
202 * the “inner encryption key” and “inner encryption iv” you
204 * 2. Base64-encode the encrypted payload message.
206 $payload = $inner_key->encrypt($magic_env->getData());
207 $magic_env->signMessage(base64_encode($payload), 'application/xml');
210 // Since we have to change the content of me:data we'll just write the
211 // whole thing from scratch. We _could_ otherwise have just manipulated
212 // that element and added the encrypted_header in the EndMagicEnvelopeToXML event.
213 $xs->elementStart('me:env', array('xmlns:me' => MagicEnvelope::NS));
214 $xs->element('me:data', array('type' => $magic_env->getDataType()), $magic_env->getData());
215 $xs->element('me:encoding', null, $magic_env->getEncoding());
216 $xs->element('me:alg', null, $magic_env->getSignatureAlgorithm());
217 $xs->element('me:sig', null, $magic_env->getSignature());
218 $xs->elementEnd('me:env');
220 $xs->elementEnd('entry');
225 public function onSalmonSlap($endpoint_uri, MagicEnvelope $magic_env, Profile $target=null)
227 $envxml = $magic_env->toXML($target, 'diaspora');
229 // Diaspora wants another POST format (base64url-encoded POST variable 'xml')
230 $headers = array('Content-Type: application/x-www-form-urlencoded');
232 // Another way to distinguish Diaspora from GNU social is that a POST with
233 // $headers=array('Content-Type: application/magic-envelope+xml') would return
234 // HTTP status code 422 Unprocessable Entity, at least as of 2015-10-04.
236 $client = new HTTPClient();
237 $client->setBody('xml=' . Magicsig::base64_url_encode($envxml));
238 $response = $client->post($endpoint_uri, $headers);
239 } catch (HTTP_Request2_Exception $e) {
240 common_log(LOG_ERR, "Diaspora-flavoured Salmon post to $endpoint_uri failed: " . $e->getMessage());
244 // 200 OK is the best response
245 // 202 Accepted is what we get from Diaspora for example
246 if (!in_array($response->getStatus(), array(200, 202))) {
247 common_log(LOG_ERR, sprintf('Salmon (from profile %d) endpoint %s returned status %s: %s',
248 $magic_env->getActor()->getID(), $endpoint_uri, $response->getStatus(), $response->getBody()));