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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';
*
* $private = \phpseclib3\Crypt\DSA::createKey();
* $public = $private->getPublicKey();
*
* $plaintext = 'terrafrost';
*
* $signature = $private->sign($plaintext);
*
* echo $public->verify($plaintext, $signature) ? 'verified' : 'unverified';
* ?>
* </code>
*
* @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 phpseclib3\Crypt;
use phpseclib3\Crypt\Common\AsymmetricKey;
use phpseclib3\Crypt\DSA\Parameters;
use phpseclib3\Crypt\DSA\PrivateKey;
use phpseclib3\Crypt\DSA\PublicKey;
use phpseclib3\Exception\InsufficientSetupException;
use phpseclib3\Math\BigInteger;
/**
* Pure-PHP FIPS 186-4 compliant implementation of DSA.
*
* @author Jim Wigginton <terrafrost@php.net>
*/
abstract class DSA extends AsymmetricKey
{
/**
* Algorithm Name
*
* @var string
*/
const ALGORITHM = 'DSA';
/**
* DSA Prime P
*
* @var \phpseclib3\Math\BigInteger
*/
protected $p;
/**
* DSA Group Order q
*
* Prime divisor of p-1
*
* @var \phpseclib3\Math\BigInteger
*/
protected $q;
/**
* DSA Group Generator G
*
* @var \phpseclib3\Math\BigInteger
*/
protected $g;
/**
* DSA public key value y
*
* @var \phpseclib3\Math\BigInteger
*/
protected $y;
/**
* Signature Format
*
* @var string
*/
protected $sigFormat;
/**
* Signature Format (Short)
*
* @var string
*/
protected $shortFormat;
/**
* Create DSA parameters
*
* @param int $L
* @param int $N
* @return \phpseclib3\Crypt\DSA|bool
*/
public static function createParameters($L = 2048, $N = 224)
{
self::initialize_static_variables();
$class = new \ReflectionClass(static::class);
if ($class->isFinal()) {
throw new \RuntimeException('createParameters() should not be called from final classes (' . static::class . ')');
}
if (!isset(self::$engines['PHP'])) {
self::useBestEngine();
}
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:
throw new \InvalidArgumentException('Invalid values for N and L');
}
$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 Parameters();
$dsa->p = $p;
$dsa->q = $q;
$dsa->g = $g;
return $dsa;
}
/**
* Create public / private key pair.
*
* This method is a bit polymorphic. It can take a DSA/Parameters object, L / N as two distinct parameters or
* no parameters (at which point L and N will be generated with this method)
*
* Returns the private key, from which the publickey can be extracted
*
* @param int[] ...$args
* @return DSA\PrivateKey
*/
public static function createKey(...$args)
{
self::initialize_static_variables();
$class = new \ReflectionClass(static::class);
if ($class->isFinal()) {
throw new \RuntimeException('createKey() should not be called from final classes (' . static::class . ')');
}
if (!isset(self::$engines['PHP'])) {
self::useBestEngine();
}
if (count($args) == 2 && is_int($args[0]) && is_int($args[1])) {
$params = self::createParameters($args[0], $args[1]);
} elseif (count($args) == 1 && $args[0] instanceof Parameters) {
$params = $args[0];
} elseif (!count($args)) {
$params = self::createParameters();
} else {
throw new InsufficientSetupException('Valid parameters are either two integers (L and N), a single DSA object or no parameters at all.');
}
$private = new PrivateKey();
$private->p = $params->p;
$private->q = $params->q;
$private->g = $params->g;
$private->x = BigInteger::randomRange(self::$one, $private->q->subtract(self::$one));
$private->y = $private->g->powMod($private->x, $private->p);
//$public = clone $private;
//unset($public->x);
return $private
->withHash($params->hash->getHash())
->withSignatureFormat($params->shortFormat);
}
/**
* OnLoad Handler
*
* @return bool
*/
protected static function onLoad(array $components)
{
if (!isset(self::$engines['PHP'])) {
self::useBestEngine();
}
if (!isset($components['x']) && !isset($components['y'])) {
$new = new Parameters();
} elseif (isset($components['x'])) {
$new = new PrivateKey();
$new->x = $components['x'];
} else {
$new = new PublicKey();
}
$new->p = $components['p'];
$new->q = $components['q'];
$new->g = $components['g'];
if (isset($components['y'])) {
$new->y = $components['y'];
}
return $new;
}
/**
* Constructor
*
* PublicKey and PrivateKey objects can only be created from abstract RSA class
*/
protected function __construct()
{
$this->sigFormat = self::validatePlugin('Signature', 'ASN1');
$this->shortFormat = 'ASN1';
parent::__construct();
}
/**
* Returns the key size
*
* More specifically, this L (the length of DSA Prime P) and N (the length of DSA Group Order q)
*
* @return array
*/
public function getLength()
{
return ['L' => $this->p->getLength(), 'N' => $this->q->getLength()];
}
/**
* Returns the current engine being used
*
* @see self::useInternalEngine()
* @see self::useBestEngine()
* @return string
*/
public function getEngine()
{
if (!isset(self::$engines['PHP'])) {
self::useBestEngine();
}
return self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods()) ?
'OpenSSL' : 'PHP';
}
/**
* Returns the parameters
*
* A public / private key is only returned if the currently loaded "key" contains an x or y
* value.
*
* @see self::getPublicKey()
* @return mixed
*/
public function getParameters()
{
$type = self::validatePlugin('Keys', 'PKCS1', 'saveParameters');
$key = $type::saveParameters($this->p, $this->q, $this->g);
return DSA::load($key, 'PKCS1')
->withHash($this->hash->getHash())
->withSignatureFormat($this->shortFormat);
}
/**
* Determines the signature padding mode
*
* Valid values are: ASN1, SSH2, Raw
*
* @param string $format
*/
public function withSignatureFormat($format)
{
$new = clone $this;
$new->shortFormat = $format;
$new->sigFormat = self::validatePlugin('Signature', $format);
return $new;
}
/**
* Returns the signature format currently being used
*
*/
public function getSignatureFormat()
{
return $this->shortFormat;
}
}
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