summaryrefslogtreecommitdiff
path: root/plugins/OStatus/lib/magicenvelope.php
blob: 457c0fba221a269695c3b97f81ad7c3159e28182 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
<?php
/**
 * StatusNet - the distributed open-source microblogging tool
 * Copyright (C) 2010, StatusNet, Inc.
 *
 * A sample module to show best practices for StatusNet plugins
 *
 * PHP version 5
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @package   StatusNet
 * @author    James Walker <james@status.net>
 * @copyright 2010 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
 * @link      http://status.net/
 */

class MagicEnvelope
{
    const ENCODING = 'base64url';

    const NS = 'http://salmon-protocol.org/ns/magic-env';
    
    private function normalizeUser($user_id)
    {
        if (substr($user_id, 0, 5) == 'http:' ||
            substr($user_id, 0, 6) == 'https:' ||
            substr($user_id, 0, 5) == 'acct:') {
            return $user_id;
        }

        if (strpos($user_id, '@') !== FALSE) {
            return 'acct:' . $user_id;
        }

        return 'http://' . $user_id;
    }

    public function getKeyPair($signer_uri)
    {
        $disco = new Discovery();

        try {
            $xrd = $disco->lookup($signer_uri);
        } catch (Exception $e) {
            return false;
        }
        if ($xrd->links) {
            if ($link = Discovery::getService($xrd->links, Magicsig::PUBLICKEYREL)) {
                list($type, $keypair) = explode(';', $link['href']);
                return $keypair;
            }
        }
        throw new Exception('Unable to locate signer public key');
    }


    public function signMessage($text, $mimetype, $signer_uri)
    {
        $signer_uri = $this->normalizeUser($signer_uri);

        if (!$this->checkAuthor($text, $signer_uri)) {
            throw new Exception("Unable to determine entry author.");
        }

        $keypair = $this->getKeyPair($signer_uri);
        if (!$keypair) {
            throw new Exception("Unable to retrive keypair for ". $signer_uri);
        }
        $signature_alg = Magicsig::fromString($keypair);
        $armored_text = base64_encode($text);

        return array(
            'data' => $armored_text,
            'encoding' => MagicEnvelope::ENCODING,
            'data_type' => $mimetype,
            'sig' => $signature_alg->sign($armored_text),
            'alg' => $signature_alg->getName()
        );
            
            
    }

    public function unfold($env)
    {
        $dom = new DOMDocument();
        $dom->loadXML(base64_decode($env['data']));

        if ($dom->documentElement->tagName != 'entry') {
            return false;
        }

        $prov = $dom->createElementNS(MagicEnvelope::NS, 'me:provenance');
        $prov->setAttribute('xmlns:me', MagicEnvelope::NS);
        $data = $dom->createElementNS(MagicEnvelope::NS, 'me:data', $env['data']);
        $data->setAttribute('type', $env['data_type']);
        $prov->appendChild($data);
        $enc = $dom->createElementNS(MagicEnvelope::NS, 'me:encoding', $env['encoding']);
        $prov->appendChild($enc);
        $alg = $dom->createElementNS(MagicEnvelope::NS, 'me:alg', $env['alg']);
        $prov->appendChild($alg);
        $sig = $dom->createElementNS(MagicEnvelope::NS, 'me:sig', $env['sig']);
        $prov->appendChild($sig);

        $dom->documentElement->appendChild($prov);

        return $dom->saveXML();
    }
    
    public function getAuthor($text) {
        $doc = new DOMDocument();
        if (!$doc->loadXML($text)) {
            return FALSE;
        }

        if ($doc->documentElement->tagName == 'entry') {
            $authors = $doc->documentElement->getElementsByTagName('author');
            foreach ($authors as $author) {
                $uris = $author->getElementsByTagName('uri');
                foreach ($uris as $uri) {
                    return $this->normalizeUser($uri->nodeValue);
                }
            }
        }
    }
    
    public function checkAuthor($text, $signer_uri)
    {
        return ($this->getAuthor($text) == $signer_uri);
    }
    
    public function verify($env)
    {
        if ($env['alg'] != 'RSA-SHA256') {
            return false;
        }

        if ($env['encoding'] != MagicEnvelope::ENCODING) {
            return false;
        }

        $text = base64_decode($env['data']);
        $signer_uri = $this->getAuthor($text);

        $verifier = Magicsig::fromString($this->getKeyPair($signer_uri));

        return $verifier->verify($env['data'], $env['sig']);
    }

    public function parse($text)
    {
        $dom = DOMDocument::loadXML($text);
        return $this->fromDom($dom);
    }

    public function fromDom($dom)
    {
        if ($dom->documentElement->tagName == 'entry') {
            $env_element = $dom->getElementsByTagNameNS(MagicEnvelope::NS, 'provenance')->item(0);
        } else if ($dom->documentElement->tagName == 'me:env') {
            $env_element = $dom->documentElement;
        } else {
            return false;
        }

        $data_element = $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'data')->item(0);
        
        return array(
            'data' => trim($data_element->nodeValue),
            'data_type' => $data_element->getAttribute('type'),
            'encoding' => $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'encoding')->item(0)->nodeValue,
            'alg' => $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'alg')->item(0)->nodeValue,
            'sig' => $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'sig')->item(0)->nodeValue,
        );
    }

}