<?php
require_once('include/certfns.php');
function receive_return($val) {
if($val >= 400)
$err = 'Error';
if($val >= 200 && $val < 300)
$err = 'OK';
logger('mod-diaspora returns ' . $val);
header($_SERVER["SERVER_PROTOCOL"] . ' ' . $val . ' ' . $err);
killme();
}
function get_diaspora_key($uri) {
$key = '';
logger('Fetching diaspora key for: ' . $uri);
$arr = lrdd($uri);
if(is_array($arr)) {
foreach($arr as $a) {
if($a['@attributes']['rel'] === 'diaspora-public-key') {
$key = base64_decode($a['@attributes']['href']);
}
}
}
else {
return '';
}
if($key)
return rsatopem($key);
return '';
}
function diaspora_base_message($type,$data) {
$tpl = get_markup_template('diaspora_' . $type . '.tpl');
if(! $tpl)
return '';
return replace_macros($tpl,$data);
}
function diaspora_msg_build($msg,$user,$contact,$prvkey,$pubkey) {
$a = get_app();
$inner_aes_key = random_string(32);
$b_inner_aes_key = base64_encode($inner_aes_key);
$inner_iv = random_string(32);
$b_inner_iv = base64_encode($inner_iv);
$outer_aes_key = random_string(32);
$b_outer_aes_key = base64_encode($outer_aes_key);
$outer_iv = random_string(32);
$b_outer_iv = base64_encode($outer_iv);
$handle = 'acct:' . $user['nickname'] . '@' . substr($a->get_baseurl(), strpos($a->get_baseurl(),'://') + 3);
$padded_data = pkcs5_pad($msg,16);
$inner_encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $inner_aes_key, $padded_data, MCRYPT_MODE_CBC, $inner_iv);
$b64_data = base64_encode($inner_encrypted);
echo "inner: $b64_data";
$b64url_data = base64url_encode($b64_data);
$b64url_stripped = str_replace(array("\n","\r"," ","\t"),array('','','',''),$b64url_data);
$lines = str_split($b64url_stripped,60);
$data = implode("\n",$lines);
$data = $data . (($data[-1] != "\n") ? "\n" : '') ;
$type = 'application/atom+xml';
$encoding = 'base64url';
$alg = 'RSA-SHA256';
$signable_data = $data . '.' . base64url_encode($type) . "\n" . '.'
. base64url_encode($encoding) . "\n" . '.' . base64url_encode($alg) . "\n";
$signature = '';
$result = openssl_sign($signable_data,$signature,$prvkey,'SHA256');
$sig = base64url_encode($signature);
$decrypted_header = <<< EOT
<decrypted_header>
<iv>$b_inner_iv</iv>
<aes_key>$b_inner_aes_key</aes_key>
<author>
<name>{$contact['name']}</name>
<uri>$handle</uri>
</author>
</decrypted_header>
EOT;
$decrypted_header = pkcs5_pad($decrypted_header,16);
logger("decrypted_header: $decrypted_header");
$ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $outer_aes_key, $decrypted_header, MCRYPT_MODE_CBC, $outer_iv);
logger( "encrypted_ciphertext: " . base64_encode($ciphertext));
logger("encrypt_outer_key: $b_outer_aes_key");
logger("ecnrypt_outer_iv: $b_outer_iv");
$outer_json = json_encode(array('iv' => $b_outer_iv,'key' => $b_outer_aes_key));
$encrypted_outer_key_bundle = '';
openssl_public_encrypt($outer_json,$encrypted_outer_key_bundle,$pubkey);
$b64_encrypted_outer_key_bundle = base64_encode($encrypted_outer_key_bundle);
$encrypted_header_json_object = json_encode(array('aes_key' => base64_encode($encrypted_outer_key_bundle),
'ciphertext' => base64_encode($ciphertext)));
$encrypted_header = '<encrypted_header>' . base64_encode($encrypted_header_json_object) . '</encrypted_header>';
$magic_env = <<< EOT
<?xml version='1.0' encoding='UTF-8'?>
<entry xmlns='http://www.w3.org/2005/Atom'>
$encrypted_header
<me:env xmlns:me="http://salmon-protocol.org/ns/magic-env">
<me:encoding>base64url</me:encoding>
<me:alg>RSA-SHA256</me:alg>
<me:data type="application/atom+xml">$data</me:data>
<me:sig>$sig</me:sig>
</me:env>
</entry>
EOT;
return $magic_env;
}
function diaspora_decode($importer,$xml) {
$basedom = parse_xml_string($xml);
if($basedom)
logger('parsed dom');
$atom = $basedom->children(NAMESPACE_ATOM1);
logger('atom: ' . count($atom));
$encrypted_header = json_decode(base64_decode($atom->encrypted_header));
print_r($encrypted_header);
$encrypted_aes_key_bundle = base64_decode($encrypted_header->aes_key);
$ciphertext = base64_decode($encrypted_header->ciphertext);
logger('encrypted_aes: ' . print_r($encrypted_aes_key_bundle,true));
logger('ciphertext: ' . print_r($ciphertext,true));
$outer_key_bundle = '';
openssl_private_decrypt($encrypted_aes_key_bundle,$outer_key_bundle,$importer['prvkey']);
logger('outer_bundle: ' . print_r($outer_key_bundle,true));
$j_outer_key_bundle = json_decode($outer_key_bundle);
$outer_iv = base64_decode($j_outer_key_bundle->iv);
$outer_key = base64_decode($j_outer_key_bundle->key);
logger("outer_iv: $outer_iv");
logger("outer_key: $outer_key");
logger("ciphertext: " . base64_encode($ciphertext));
$decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $outer_key, $ciphertext, MCRYPT_MODE_CBC, $outer_iv);
$decrypted = pkcs5_unpad($decrypted);
logger('decrypted: ' . print_r($decrypted,true));
/**
* $decrypted now contains something like
*
* <decrypted_header>
* <iv>8e+G2+ET8l5BPuW0sVTnQw==</iv>
* <aes_key>UvSMb4puPeB14STkcDWq+4QE302Edu15oaprAQSkLKU=</aes_key>
* <author>
* <name>Ryan Hughes</name>
* <uri>acct:galaxor@diaspora.pirateship.org</uri>
* </author>
* </decrypted_header>
*/
$idom = parse_xml_string($decrypted,false);
$inner_iv = base64_decode($idom->iv);
$inner_aes_key = base64_decode($idom->aes_key);
logger('idom: ' . print_r($idom,true));
$author_link = str_replace('acct:','',$idom->author->uri);
logger('inner_iv: ' . $inner_iv);
$dom = $basedom->children(NAMESPACE_SALMON_ME);
if($dom)
logger('have dom');
logger('dom: ' . count($dom));
// figure out where in the DOM tree our data is hiding
if($dom->provenance->data)
$base = $dom->provenance;
elseif($dom->env->data)
$base = $dom->env;
elseif($dom->data)
$base = $dom;
if(! $base) {
logger('mod-diaspora: unable to locate salmon data in xml ');
dt_return(400);
}
// Stash the signature away for now. We have to find their key or it won't be good for anything.
$signature = base64url_decode($base->sig);
logger('signature: ' . bin2hex($signature));
// unpack the data
// strip whitespace so our data element will return to one big base64 blob
$data = str_replace(array(" ","\t","\r","\n"),array("","","",""),$base->data);
// Add back the 60 char linefeeds
$lines = str_split($data,60);
$data = implode("\n",$lines);
// stash away some other stuff for later
$type = $base->data[0]->attributes()->type[0];
$keyhash = $base->sig[0]->attributes()->keyhash[0];
$encoding = $base->encoding;
$alg = $base->alg;
$signed_data = $data . (($data[-1] != "\n") ? "\n" : '') . '.' . base64url_encode($type) . "\n" . '.' . base64url_encode($encoding) . "\n" . '.' . base64url_encode($alg) . "\n";
logger('signed data: ' . $signed_data);
// decode the data
$data = base64url_decode($data);
// Now pull out the inner encrypted blob
$inner_encrypted = base64_decode($data);
$inner_decrypted =
$inner_decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $inner_aes_key, $inner_encrypted, MCRYPT_MODE_CBC, $inner_iv);
$inner_decrypted = pkcs5_unpad($inner_decrypted);
logger('inner_decrypted: ' . $inner_decrypted);
if(! $author_link) {
logger('mod-diaspora: Could not retrieve author URI.');
receive_return(400);
}
// Once we have the author URI, go to the web and try to find their public key
// *** or look it up locally ***
logger('mod-diaspora: Fetching key for ' . $author_link );
// Get diaspora public key (pkcs#1) and convert to pkcs#8
$key = get_diaspora_key($author_link);
if(! $key) {
logger('mod-salmon: Could not retrieve author key.');
receive_return(400);
}
$verify = false;
if (version_compare(PHP_VERSION, '5.3.0', '>=')) {
$verify = openssl_verify($signed_data,$signature,$key,'sha256');
}
else {
// fallback sha256 verify for PHP < 5.3
$rawsig = '';
$hash = hash('sha256',$signed_data,true);
openssl_public_decrypt($signature,$rawsig,$key);
$verify = (($rawsig && substr($rawsig,-32) === $hash) ? true : false);
}
if(! $verify) {
logger('mod-diaspora: Message did not verify. Discarding.');
receive_return(400);
}
logger('mod-diaspora: Message verified.');
return $inner_decrypted;
}
