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tgseclib/phpseclib/Crypt/DSA.php
Sokolovskyy Roman ccfb6c92bf Set of PHPDOC fixes
2017-08-03 09:16:37 +02:00

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<?php
/**
* Pure-PHP FIPS 186-4 compliant implementation of DSA.
*
* PHP version 5
*
* Here's an example of how to create signatures and verify signatures with this library:
* <code>
* <?php
* include 'vendor/autoload.php';
*
* extract(\phpseclib\Crypt\DSA::createKey());
*
* $plaintext = 'terrafrost';
*
* $signature = $privatekey->sign($plaintext, 'ASN1');
*
* echo $publickey->verify($plaintext, $signature) ? 'verified' : 'unverified';
* ?>
* </code>
*
* @category Crypt
* @package DSA
* @author Jim Wigginton <terrafrost@php.net>
* @copyright 2016 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
*/
namespace phpseclib\Crypt;
use ParagonIE\ConstantTime\Base64;
use phpseclib\File\ASN1;
use phpseclib\Math\BigInteger;
use phpseclib\Crypt\Common\AsymmetricKey;
use phpseclib\Common\Functions\Strings;
/**
* Pure-PHP FIPS 186-4 compliant implementation of DSA.
*
* @package DSA
* @author Jim Wigginton <terrafrost@php.net>
* @access public
*/
class DSA extends AsymmetricKey
{
/**
* Algorithm Name
*
* @var string
* @access private
*/
const ALGORITHM = 'DSA';
/**
* DSA Prime P
*
* @var \phpseclib\Math\BigInteger
* @access private
*/
private $p;
/**
* DSA Group Order q
*
* Prime divisor of p-1
*
* @var \phpseclib\Math\BigInteger
* @access private
*/
protected $q;
/**
* DSA Group Generator G
*
* @var \phpseclib\Math\BigInteger
* @access private
*/
private $g;
/**
* DSA secret exponent x
*
* @var \phpseclib\Math\BigInteger
* @access private
*/
protected $x;
/**
* DSA public key value y
*
* @var \phpseclib\Math\BigInteger
* @access private
*/
private $y;
/**
* Parameters Format
*
* @var string
* @access private
*/
private $parametersFormat = 'PKCS1';
/**
* Create DSA parameters
*
* @access public
* @param int $L
* @param int $N
* @return \phpseclib\Crypt\DSA|bool
*/
static function createParameters($L = 2048, $N = 224)
{
self::initialize_static_variables();
switch (true) {
case $N == 160:
/*
in FIPS 186-1 and 186-2 N was fixed at 160 whereas K had an upper bound of 1024.
RFC 4253 (SSH Transport Layer Protocol) references FIPS 186-2 and as such most
SSH DSA implementations only support keys with an N of 160.
puttygen let's you set the size of L (but not the size of N) and uses 2048 as the
default L value. that's not really compliant with any of the FIPS standards, however,
for the purposes of maintaining compatibility with puttygen, we'll support it
*/
//case ($L >= 512 || $L <= 1024) && (($L & 0x3F) == 0) && $N == 160:
// FIPS 186-3 changed this as follows:
//case $L == 1024 && $N == 160:
case $L == 2048 && $N == 224:
case $L == 2048 && $N == 256:
case $L == 3072 && $N == 256:
break;
default:
return false;
}
$two = new BigInteger(2);
$q = BigInteger::randomPrime($N);
$divisor = $q->multiply($two);
do {
$x = BigInteger::random($L);
list(, $c) = $x->divide($divisor);
$p = $x->subtract($c->subtract(self::$one));
} while ($p->getLength() != $L || !$p->isPrime());
$p_1 = $p->subtract(self::$one);
list($e) = $p_1->divide($q);
// quoting http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf#page=50 ,
// "h could be obtained from a random number generator or from a counter that
// changes after each use". PuTTY (sshdssg.c) starts h off at 1 and increments
// it on each loop. wikipedia says "commonly h = 2 is used" so we'll just do that
$h = clone $two;
while (true) {
$g = $h->powMod($e, $p);
if (!$g->equals(self::$one)) {
break;
}
$h = $h->add(self::$one);
}
$dsa = new DSA();
$dsa->p = $p;
$dsa->q = $q;
$dsa->g = $g;
return $dsa;
}
/**
* Create public / private key pair.
*
* This method is a bit polymorphic. It can take a DSA object (eg. pre-loaded with parameters),
* L / N as two distinct parameters or no parameters (at which point L and N will be generated
* with this method)
*
* Returns an array with the following two elements:
* - 'privatekey': The private key.
* - 'publickey': The public key.
*
* @access public
* @return array|DSA
*/
static function createKey()
{
self::initialize_static_variables();
$args = func_get_args();
if (count($args) == 2 && is_int($args[0]) && is_int($args[1])) {
$private = self::createParameters($args[0], $args[1]);
} else if (count($args) == 1 && $args[0] instanceof DSA) {
$private = clone $args[0];
} else if (!count($args)) {
$private = self::createParameters();
} else {
throw new \InvalidArgumentException('Valid parameters are either two integers (L and N), a single DSA object or no parameters at all.');
}
$private->x = BigInteger::randomRange(self::$one, $private->q->subtract(self::$one));
$private->y = $private->g->powMod($private->x, $private->p);
$public = clone $private;
unset($public->x);
return ['privatekey' => $private, 'publickey' => $public];
}
/**
* Loads a public or private key
*
* Returns true on success and false on failure (ie. an incorrect password was provided or the key was malformed)
*
* @access public
* @param string $key
* @param int $type optional
*/
public function load($key, $type = false)
{
if ($key instanceof DSA) {
$this->privateKeyFormat = $key->privateKeyFormat;
$this->publicKeyFormat = $key->publicKeyFormat;
$this->format = $key->format;
$this->p = $key->p;
$this->q = $key->q;
$this->g = $key->g;
$this->x = $key->x;
$this->y = $key->y;
$this->parametersFormat = $key->parametersFormat;
return true;
}
$components = parent::load($key, $type);
if ($components === false) {
return false;
}
if (isset($components['p'])) {
switch (true) {
case isset($this->p) && !$this->p->equals($components['p']):
case isset($this->q) && !$this->q->equals($components['q']):
case isset($this->g) && !$this->g->equals($components['g']):
$this->x = $this->y = null;
}
$this->p = $components['p'];
$this->q = $components['q'];
$this->g = $components['g'];
}
if (isset($components['x'])) {
$this->x = $components['x'];
}
if (isset($components['y'])) {
$this->y = $components['y'];
}
//} else if (isset($components['x'])) {
// $this->y = $this->g->powMod($this->x, $this->p);
//}
return true;
}
/**
* Returns the key size
*
* More specifically, this L (the length of DSA Prime P) and N (the length of DSA Group Order q)
*
* @access public
* @return array
*/
public function getLength()
{
return isset($this->p) ?
['L' => $this->p->getLength(), 'N' => $this->q->getLength()] :
['L' => 0, 'N' => 0];
}
/**
* __toString() magic method
*
* @access public
* @return string
*/
public function __toString()
{
$key = parent::__toString();
if (!empty($key)) {
return $key;
}
try {
$key = $this->getParameters($this->parametersFormat);
return is_string($key) ? $key : '';
} catch (\Exception $e) {
return '';
}
}
/**
* Returns the private key
*
* PKCS1 DSA private keys contain x and y. PKCS8 DSA private keys just contain x
* but y can be derived from x.
*
* @see self::getPublicKey()
* @access public
* @param string $type optional
* @return mixed
*/
public function getPrivateKey($type = 'PKCS8')
{
$type = self::validatePlugin('Keys', $type, 'savePrivateKey');
if ($type === false) {
return false;
}
if (!isset($this->x)) {
return false;
}
if (!isset($this->y)) {
$this->y = $this->g->powMod($this->x, $this->p);
}
return $type::savePrivateKey($this->p, $this->q, $this->g, $this->y, $this->x, $this->password);
}
/**
* Returns the public key
*
* If you do "openssl rsa -in private.rsa -pubout -outform PEM" you get a PKCS8 formatted key
* that contains a publicKeyAlgorithm AlgorithmIdentifier and a publicKey BIT STRING.
* An AlgorithmIdentifier contains an OID and a parameters field. With RSA public keys this
* parameters field is NULL. With DSA PKCS8 public keys it is not - it contains the p, q and g
* variables. The publicKey BIT STRING contains, simply, the y variable. This can be verified
* by getting a DSA PKCS8 public key:
*
* "openssl dsa -in private.dsa -pubout -outform PEM"
*
* ie. just swap out rsa with dsa in the rsa command above.
*
* A PKCS1 public key corresponds to the publicKey portion of the PKCS8 key. In the case of RSA
* the publicKey portion /is/ the key. In the case of DSA it is not. You cannot verify a signature
* without the parameters and the PKCS1 DSA public key format does not include the parameters.
*
* @see self::getPrivateKey()
* @access public
* @param string $type optional
* @return mixed
*/
public function getPublicKey($type = 'PKCS8')
{
$type = self::validatePlugin('Keys', $type, 'savePublicKey');
if ($type === false) {
return false;
}
if (!isset($this->y)) {
if (!isset($this->x) || !isset($this->p)) {
return false;
}
$this->y = $this->g->powMod($this->x, $this->p);
}
return $type::savePublicKey($this->p, $this->q, $this->g, $this->y);
}
/**
* Returns the parameters
*
* A public / private key is only returned if the currently loaded "key" contains an x or y
* value.
*
* @see self::getPublicKey()
* @see self::getPrivateKey()
* @access public
* @param string $type optional
* @return mixed
*/
public function getParameters($type = 'PKCS1')
{
$type = self::validatePlugin('Keys', $type, 'saveParameters');
if ($type === false) {
return false;
}
if (!isset($this->p) || !isset($this->q) || !isset($this->g)) {
return false;
}
return $type::saveParameters($this->p, $this->q, $this->g);
}
/**
* Create a signature
*
* @see self::verify()
* @access public
* @param string $message
* @param string $format optional
* @return mixed
*/
function sign($message, $format = 'Raw')
{
$format = self::validatePlugin('Signature', $format);
if ($format === false) {
return false;
}
if (empty($this->x) || empty($this->p)) {
return false;
}
while (true) {
$k = BigInteger::randomRange(self::$one, $this->q->subtract(self::$one));
$r = $this->g->powMod($k, $this->p);
list(, $r) = $r->divide($this->q);
if ($r->equals(self::$zero)) {
continue;
}
$kinv = $k->modInverse($this->q);
$h = $this->hash->hash($message);
$h = $this->bits2int($h);
$temp = $h->add($this->x->multiply($r));
$temp = $kinv->multiply($temp);
list(, $s) = $temp->divide($this->q);
if (!$s->equals(self::$zero)) {
break;
}
}
// the following is an RFC6979 compliant implementation of deterministic DSA
// it's unused because it's mainly intended for use when a good CSPRNG isn't
// available. if phpseclib's CSPRNG isn't good then even key generation is
// suspect
/*
$h1 = $this->hash->hash($message);
$k = $this->computek($h1);
$r = $this->g->powMod($k, $this->p);
list(, $r) = $r->divide($this->q);
$kinv = $k->modInverse($this->q);
$h1 = $this->bits2int($h1);
$temp = $h1->add($this->x->multiply($r));
$temp = $kinv->multiply($temp);
list(, $s) = $temp->divide($this->q);
*/
return $format::save($r, $s);
}
/**
* Verify a signature
*
* @see self::verify()
* @access public
* @param string $message
* @param string $format optional
* @return mixed
*/
function verify($message, $signature, $format = 'Raw')
{
$format = self::validatePlugin('Signature', $format);
if ($format === false) {
return false;
}
$params = $format::load($signature);
if ($params === false || count($params) != 2) {
return false;
}
extract($params);
if (empty($this->y) || empty($this->p)) {
return false;
}
$q_1 = $this->q->subtract(self::$one);
if (!$r->between(self::$one, $q_1) || !$s->between(self::$one, $q_1)) {
return false;
}
$w = $s->modInverse($this->q);
$h = $this->hash->hash($message);
$h = $this->bits2int($h);
list(, $u1) = $h->multiply($w)->divide($this->q);
list(, $u2) = $r->multiply($w)->divide($this->q);
$v1 = $this->g->powMod($u1, $this->p);
$v2 = $this->y->powMod($u2, $this->p);
list(, $v) = $v1->multiply($v2)->divide($this->p);
list(, $v) = $v->divide($this->q);
return Strings::equals($v->toBytes(), $r->toBytes());
}
}
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