11c57e7aee
This removes most references to Google, with some remaining since they may point to things which are still relevant. References to Google Code, Google Buzz and Google Maps have been removed
439 lines
17 KiB
PHP
439 lines
17 KiB
PHP
<?php
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/**
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* StatusNet - the distributed open-source microblogging tool
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* Copyright (C) 2010, StatusNet, Inc.
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*
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* A sample module to show best practices for StatusNet plugins
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*
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* PHP version 5
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @package StatusNet
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* @author James Walker <james@status.net>
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* @copyright 2010 StatusNet, Inc.
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* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
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* @link http://status.net/
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*/
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class MagicEnvelope
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{
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const ENCODING = 'base64url';
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const NS = 'http://salmon-protocol.org/ns/magic-env';
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protected $actor = null; // Profile of user who has signed the envelope
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protected $data = null; // When stored here it is _always_ base64url encoded
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protected $data_type = null;
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protected $encoding = null;
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protected $alg = null;
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protected $sig = null;
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/**
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* Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
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*
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* @param string XML source
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* @return mixed associative array of envelope data, or false on unrecognized input
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*
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* @fixme will spew errors to logs or output in case of XML parse errors
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* @fixme may give fatal errors if some elements are missing or invalid XML
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* @fixme calling DOMDocument::loadXML statically triggers warnings in strict mode
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*/
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public function __construct($xml=null, Profile $actor=null) {
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if (!empty($xml)) {
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$dom = new DOMDocument();
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if (!$dom->loadXML($xml)) {
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throw new ServerException('Tried to load malformed XML as DOM');
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} elseif (!$this->fromDom($dom)) {
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throw new ServerException('Could not load MagicEnvelope from DOM');
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}
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} elseif ($actor instanceof Profile) {
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// So far we only allow setting with _either_ $xml _or_ $actor as that's
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// all our circumstances require. But it may be confusing for new developers.
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// The idea is that feeding XML must be followed by interpretation and then
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// running $magic_env->verify($profile), just as in SalmonAction->prepare(...)
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// and supplying an $actor (which right now has to be a User) will require
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// defining the $data, $data_type etc. attributes manually afterwards before
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// signing the envelope..
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$this->setActor($actor);
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}
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}
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/**
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* Retrieve Salmon keypair first by checking local database, but
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* if it's not found, attempt discovery if it has been requested.
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*
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* @param Profile $profile The profile we're looking up keys for.
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* @param boolean $discovery Network discovery if no local cache?
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*/
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public function getKeyPair(Profile $profile, $discovery=false) {
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if (!$profile->isLocal()) common_debug('Getting magic-public-key for non-local profile id=='.$profile->getID());
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$magicsig = Magicsig::getKV('user_id', $profile->getID());
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if ($discovery && !$magicsig instanceof Magicsig) {
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if (!$profile->isLocal()) common_debug('magic-public-key not found, will do discovery for profile id=='.$profile->getID());
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// Throws exception on failure, but does not try to _load_ the keypair string.
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$keypair = $this->discoverKeyPair($profile);
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$magicsig = new Magicsig();
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$magicsig->user_id = $profile->getID();
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$magicsig->importKeys($keypair);
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// save the public key for this profile in our database.
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// TODO: If the profile generates a new key remotely, we must be able to replace
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// this (of course after callback-verification).
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$magicsig->insert();
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} elseif (!$magicsig instanceof Magicsig) { // No discovery request, so we'll give up.
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throw new ServerException(sprintf('No public key found for profile (id==%d)', $profile->id));
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}
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assert($magicsig->publicKey instanceof Crypt_RSA);
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return $magicsig;
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}
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/**
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* Get the Salmon keypair from a URI, uses XRD Discovery etc. Reasonably
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* you'll only get the public key ;)
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*
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* The string will (hopefully) be formatted as described in Magicsig specification:
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*
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* @return string formatted as Magicsig keypair
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*/
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public function discoverKeyPair(Profile $profile)
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{
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$signer_uri = $profile->getUri();
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if (empty($signer_uri)) {
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throw new ServerException(sprintf('Profile missing URI (id==%d)', $profile->getID()));
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}
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$disco = new Discovery();
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// Throws exception on lookup problems
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try {
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$xrd = $disco->lookup($signer_uri);
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} catch (Exception $e) {
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// Diaspora seems to require us to request the acct: uri
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$xrd = $disco->lookup($profile->getAcctUri());
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}
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common_debug('Will try to find magic-public-key from XRD of profile id=='.$profile->getID());
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$pubkey = null;
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if (Event::handle('MagicsigPublicKeyFromXRD', array($xrd, &$pubkey))) {
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$link = $xrd->get(Magicsig::PUBLICKEYREL);
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if (is_null($link)) {
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// TRANS: Exception.
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throw new Exception(_m('Unable to locate signer public key.'));
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}
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$pubkey = $link->href;
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}
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if (empty($pubkey)) {
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throw new ServerException('Empty Magicsig public key. A bug?');
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}
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// We have a public key element, let's hope it has proper key data.
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$keypair = false;
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$parts = explode(',', $pubkey);
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if (count($parts) == 2) {
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$keypair = $parts[1];
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} else {
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// Backwards compatibility check for separator bug in 0.9.0
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$parts = explode(';', $pubkey);
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if (count($parts) == 2) {
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$keypair = $parts[1];
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}
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}
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if ($keypair === false) {
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// For debugging clarity. Keypair did not pass count()-check above.
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// TRANS: Exception when public key was not properly formatted.
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throw new Exception(_m('Incorrectly formatted public key element.'));
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}
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return $keypair;
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}
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/**
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* The current MagicEnvelope spec as used in StatusNet 0.9.7 and later
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* includes both the original data and some signing metadata fields as
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* the input plaintext for the signature hash.
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*
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* @return string
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*/
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public function signingText() {
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return implode('.', array($this->data, // this field is pre-base64'd
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Magicsig::base64_url_encode($this->data_type),
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Magicsig::base64_url_encode($this->encoding),
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Magicsig::base64_url_encode($this->alg)));
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}
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/**
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*
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* @param <type> $text
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* @param <type> $mimetype
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* @param Magicsig $magicsig Magicsig with private key available.
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*
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* @return MagicEnvelope object with all properties set
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*
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* @throws Exception of various kinds on signing failure
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*/
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public function signMessage($text, $mimetype)
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{
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if (!$this->actor instanceof Profile) {
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throw new ServerException('No profile to sign message with is set.');
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} elseif (!$this->actor->isLocal()) {
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throw new ServerException('Cannot sign magic envelopes with remote users since we have no private key.');
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}
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// Find already stored key
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$magicsig = Magicsig::getKV('user_id', $this->actor->getID());
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if (!$magicsig instanceof Magicsig) {
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// and if it doesn't exist, it is time to create one!
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$magicsig = Magicsig::generate($this->actor->getUser());
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}
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assert($magicsig instanceof Magicsig);
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assert($magicsig->privateKey instanceof Crypt_RSA);
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// Prepare text and metadata for signing
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$this->data = Magicsig::base64_url_encode($text);
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$this->data_type = $mimetype;
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$this->encoding = self::ENCODING;
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$this->alg = $magicsig->getName();
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// Get the actual signature
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$this->sig = $magicsig->sign($this->signingText());
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}
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/**
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* Create an <me:env> XML representation of the envelope.
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*
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* @return string representation of XML document
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*/
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public function toXML(Profile $target=null, $flavour=null) {
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$xs = new XMLStringer();
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$xs->startXML(); // header, to point out it's not HTML or anything...
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if (Event::handle('StartMagicEnvelopeToXML', array($this, $xs, $flavour, $target))) {
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// fall back to our default, normal Magic Envelope XML.
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// the $xs element _may_ have had elements added, or could get in the end event
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$xs->elementStart('me:env', array('xmlns:me' => self::NS));
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$xs->element('me:data', array('type' => $this->data_type), $this->data);
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$xs->element('me:encoding', null, $this->encoding);
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$xs->element('me:alg', null, $this->alg);
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$xs->element('me:sig', null, $this->getSignature());
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$xs->elementEnd('me:env');
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Event::handle('EndMagicEnvelopeToXML', array($this, $xs, $flavour, $target));
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}
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return $xs->getString();
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}
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/*
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* Extract the contained XML payload, and insert a copy of the envelope
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* signature data as an <me:provenance> section.
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*
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* @return DOMDocument of Atom entry
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*
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* @fixme in case of XML parsing errors, this will spew to the error log or output
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*/
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public function getPayload()
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{
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$dom = new DOMDocument();
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if (!$dom->loadXML(Magicsig::base64_url_decode($this->data))) {
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throw new ClientException('Malformed XML in Salmon payload');
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}
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switch ($this->data_type) {
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case 'application/atom+xml':
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if ($dom->documentElement->namespaceURI !== Activity::ATOM
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|| $dom->documentElement->tagName !== 'entry') {
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throw new ServerException(_m('Salmon post must be an Atom entry.'));
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}
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$prov = $dom->createElementNS(self::NS, 'me:provenance');
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$prov->setAttribute('xmlns:me', self::NS);
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$data = $dom->createElementNS(self::NS, 'me:data', $this->data);
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$data->setAttribute('type', $this->data_type);
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$prov->appendChild($data);
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$enc = $dom->createElementNS(self::NS, 'me:encoding', $this->encoding);
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$prov->appendChild($enc);
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$alg = $dom->createElementNS(self::NS, 'me:alg', $this->alg);
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$prov->appendChild($alg);
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$sig = $dom->createElementNS(self::NS, 'me:sig', $this->getSignature());
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$prov->appendChild($sig);
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$dom->documentElement->appendChild($prov);
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break;
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default:
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throw new ClientException('Unknown Salmon payload data type');
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}
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return $dom;
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}
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public function getSignature()
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{
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if (empty($this->sig)) {
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throw new ServerException('You must first call signMessage before getSignature');
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}
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return $this->sig;
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}
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public function getSignatureAlgorithm()
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{
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return $this->alg;
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}
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public function getData()
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{
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return $this->data;
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}
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public function getDataType()
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{
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return $this->data_type;
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}
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public function getEncoding()
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{
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return $this->encoding;
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}
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/**
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* Find the author URI referenced in the payload Atom entry.
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*
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* @return string URI for author
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* @throws ServerException on failure
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*/
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public function getAuthorUri() {
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$doc = $this->getPayload();
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$authors = $doc->documentElement->getElementsByTagName('author');
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foreach ($authors as $author) {
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$uris = $author->getElementsByTagName('uri');
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foreach ($uris as $uri) {
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return $uri->nodeValue;
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}
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}
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throw new ServerException('No author URI found in Salmon payload data');
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}
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/**
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* Attempt to verify cryptographic signing for parsed envelope data.
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* Requires network access to retrieve public key referenced by the envelope signer.
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*
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* Details of failure conditions are dumped to output log and not exposed to caller.
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*
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* @param Profile $profile profile used to get locally cached public signature key
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* or if necessary perform discovery on.
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*
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* @return boolean
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*/
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public function verify(Profile $profile)
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{
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if ($this->alg != 'RSA-SHA256') {
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common_log(LOG_DEBUG, 'Salmon error: bad algorithm: '._ve($this->alg));
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return false;
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}
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if ($this->encoding != self::ENCODING) {
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common_log(LOG_DEBUG, 'Salmon error: bad encoding: '._ve($this->encoding));
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return false;
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}
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try {
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$magicsig = $this->getKeyPair($profile, true); // Do discovery too if necessary
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} catch (Exception $e) {
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common_log(LOG_DEBUG, "Salmon error: getKeyPair for profile id=={$profile->getID()}: "._ve($e->getMessage()));
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return false;
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}
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if (!$magicsig->verify($this->signingText(), $this->getSignature())) {
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common_log(LOG_INFO, 'Salmon signature verification failed for profile id=='.$profile->getID());
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// TRANS: Client error when incoming salmon slap signature does not verify cryptographically.
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throw new ClientException(_m('Salmon signature verification failed.'));
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}
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common_debug('Salmon signature verification successful for profile id=='.$profile->getID());
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$this->setActor($profile);
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return true;
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}
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/**
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* Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
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*
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* @param DOMDocument $dom
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* @return mixed associative array of envelope data, or false on unrecognized input
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*
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* @fixme may give fatal errors if some elements are missing
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*/
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protected function fromDom(DOMDocument $dom)
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{
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$env_element = $dom->getElementsByTagNameNS(self::NS, 'env')->item(0);
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if (!$env_element) {
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$env_element = $dom->getElementsByTagNameNS(self::NS, 'provenance')->item(0);
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}
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if (!$env_element) {
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return false;
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}
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$data_element = $env_element->getElementsByTagNameNS(self::NS, 'data')->item(0);
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$sig_element = $env_element->getElementsByTagNameNS(self::NS, 'sig')->item(0);
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$this->data = preg_replace('/\s/', '', $data_element->nodeValue);
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$this->data_type = $data_element->getAttribute('type');
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$this->encoding = $env_element->getElementsByTagNameNS(self::NS, 'encoding')->item(0)->nodeValue;
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$this->alg = $env_element->getElementsByTagNameNS(self::NS, 'alg')->item(0)->nodeValue;
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$this->sig = preg_replace('/\s/', '', $sig_element->nodeValue);
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return true;
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}
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public function setActor(Profile $actor)
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{
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if ($this->actor instanceof Profile) {
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throw new ServerException('Cannot set a new actor profile for MagicEnvelope object.');
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}
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$this->actor = $actor;
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}
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public function getActor()
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{
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if (!$this->actor instanceof Profile) {
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throw new ServerException('No actor set for this magic envelope.');
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}
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return $this->actor;
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}
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/**
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* Encode the given string as a signed MagicEnvelope XML document,
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* using the keypair for the given local user profile. We can of
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* course not sign a remote profile's slap, since we don't have the
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* private key.
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*
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* Side effects: will create and store a keypair on-demand if one
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* hasn't already been generated for this user. This can be very slow
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* on some systems.
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*
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* @param string $text XML fragment to sign, assumed to be Atom
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* @param User $user User who cryptographically signs $text
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*
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* @return MagicEnvelope object complete with signature
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*
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* @throws Exception on bad profile input or key generation problems
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*/
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public static function signAsUser($text, User $user)
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{
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$magic_env = new MagicEnvelope(null, $user->getProfile());
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$magic_env->signMessage($text, 'application/atom+xml');
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return $magic_env;
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}
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}
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