gnu-social/plugins/OStatus/classes/Magicsig.php

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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/
*/
if (!defined('STATUSNET')) {
exit(1);
}
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require_once 'Crypt/RSA.php';
class Magicsig extends Managed_DataObject
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{
const PUBLICKEYREL = 'magic-public-key';
public $__table = 'magicsig';
/**
* Key to user.id/profile.id for the local user whose key we're storing.
*
* @var int
*/
public $user_id;
/**
* Flattened string representation of the key pair; callers should
* usually use $this->publicKey and $this->privateKey directly,
* which hold live Crypt_RSA key objects.
*
* @var string
*/
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public $keypair;
/**
* Crypto algorithm used for this key; currently only RSA-SHA256 is supported.
*
* @var string
*/
public $alg;
/**
* Public RSA key; gets serialized in/out via $this->keypair string.
*
* @var Crypt_RSA
*/
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public $publicKey;
/**
* PrivateRSA key; gets serialized in/out via $this->keypair string.
*
* @var Crypt_RSA
*/
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public $privateKey;
public function __construct($alg = 'RSA-SHA256')
{
$this->alg = $alg;
}
/**
* Fetch a Magicsig object from the cache or database on a field match.
*
* @param string $k
* @param mixed $v
* @return Magicsig
*/
static function getKV($k, $v=null)
{
$obj = parent::getKV($k, $v);
if ($obj instanceof Magicsig) {
// Please note we're replacing the $obj
// FIXME: There should be an import-key that modifies the fetched $obj
$obj = Magicsig::fromString($obj->keypair);
// Never allow less than 1024 bit keys.
// The only case these show up in would be imported or
// legacy very-old-StatusNet generated keypairs.
if (strlen($obj->publicKey->modulus->toBits()) < 1024) {
$obj->delete();
return false;
}
}
return $obj;
}
public static function schemaDef()
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{
return array(
'fields' => array(
'user_id' => array('type' => 'int', 'not null' => true, 'description' => 'user id'),
'keypair' => array('type' => 'text', 'description' => 'keypair text representation'),
'alg' => array('type' => 'varchar', 'length' => 64, 'description' => 'algorithm'),
),
'primary key' => array('user_id'),
'foreign keys' => array(
'magicsig_user_id_fkey' => array('user', array('user_id' => 'id')),
),
);
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}
/**
* Save this keypair into the database.
*
* Overloads default insert behavior to encode the live key objects
* as a flat string for storage.
*
* @return mixed
*/
function insert()
{
$this->keypair = $this->toString();
return parent::insert();
}
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/**
* Generate a new keypair for a local user and store in the database.
*
* Warning: this can be very slow on systems without the GMP module.
* Runtimes of 20-30 seconds are not unheard-of.
*
* @param int $user_id id of local user we're creating a key for
*/
public function generate($user_id, $bits=1024)
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{
$rsa = new Crypt_RSA();
$keypair = $rsa->createKey($bits);
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$rsa->loadKey($keypair['privatekey']);
$this->privateKey = new Crypt_RSA();
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$this->privateKey->loadKey($keypair['privatekey']);
$this->publicKey = new Crypt_RSA();
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$this->publicKey->loadKey($keypair['publickey']);
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$this->user_id = $user_id;
$this->insert();
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}
/**
* Encode the keypair or public key as a string.
*
* @param boolean $full_pair set to false to leave out the private key.
* @return string
*/
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public function toString($full_pair = true)
{
$mod = Magicsig::base64_url_encode($this->publicKey->modulus->toBytes());
$exp = Magicsig::base64_url_encode($this->publicKey->exponent->toBytes());
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$private_exp = '';
if ($full_pair && $this->privateKey->exponent->toBytes()) {
$private_exp = '.' . Magicsig::base64_url_encode($this->privateKey->exponent->toBytes());
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}
return 'RSA.' . $mod . '.' . $exp . $private_exp;
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}
/**
* Decode a string representation of an RSA public key or keypair
* as a Magicsig object which can be used to sign or verify.
*
* @param string $text
* @return Magicsig
*/
public static function fromString($text)
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{
$magic_sig = new Magicsig();
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// remove whitespace
$text = preg_replace('/\s+/', '', $text);
// parse components
if (!preg_match('/RSA\.([^\.]+)\.([^\.]+)(.([^\.]+))?/', $text, $matches)) {
return false;
}
$mod = $matches[1];
$exp = $matches[2];
if (!empty($matches[4])) {
$private_exp = $matches[4];
} else {
$private_exp = false;
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}
$magic_sig->loadKey($mod, $exp, 'public');
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if ($private_exp) {
$magic_sig->loadKey($mod, $private_exp, 'private');
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}
return $magic_sig;
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}
/**
* Fill out $this->privateKey or $this->publicKey with a Crypt_RSA object
* representing the give key (as mod/exponent pair).
*
* @param string $mod base64-encoded
* @param string $exp base64-encoded exponent
* @param string $type one of 'public' or 'private'
*/
public function loadKey($mod, $exp, $type = 'public')
{
common_log(LOG_DEBUG, "Adding ".$type." key: (".$mod .', '. $exp .")");
$rsa = new Crypt_RSA();
$rsa->signatureMode = CRYPT_RSA_SIGNATURE_PKCS1;
$rsa->setHash('sha256');
$rsa->modulus = new Math_BigInteger(Magicsig::base64_url_decode($mod), 256);
$rsa->k = strlen($rsa->modulus->toBytes());
$rsa->exponent = new Math_BigInteger(Magicsig::base64_url_decode($exp), 256);
if ($type == 'private') {
$this->privateKey = $rsa;
} else {
$this->publicKey = $rsa;
}
}
/**
* Returns the name of the crypto algorithm used for this key.
*
* @return string
*/
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public function getName()
{
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return $this->alg;
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}
/**
* Returns the name of a hash function to use for signing with this key.
*
* @return string
* @fixme is this used? doesn't seem to be called by name.
*/
public function getHash()
{
switch ($this->alg) {
case 'RSA-SHA256':
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return 'sha256';
}
}
/**
* Generate base64-encoded signature for the given byte string
* using our private key.
*
* @param string $bytes as raw byte string
* @return string base64-encoded signature
*/
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public function sign($bytes)
{
$sig = $this->privateKey->sign($bytes);
return Magicsig::base64_url_encode($sig);
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}
/**
*
* @param string $signed_bytes as raw byte string
* @param string $signature as base64
* @return boolean
*/
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public function verify($signed_bytes, $signature)
{
$signature = Magicsig::base64_url_decode($signature);
return $this->publicKey->verify($signed_bytes, $signature);
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}
/**
* URL-encoding-friendly base64 variant encoding.
*
* @param string $input
* @return string
*/
public static function base64_url_encode($input)
{
return strtr(base64_encode($input), '+/', '-_');
}
/**
* URL-encoding-friendly base64 variant decoding.
*
* @param string $input
* @return string
*/
public static function base64_url_decode($input)
{
return base64_decode(strtr($input, '-_', '+/'));
}
}