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<?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,
);
}
}
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