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<?php
/**
* DSA Private Key
*
* @author Jim Wigginton <terrafrost@php.net>
* @copyright 2015 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
*/
namespace phpseclib3\Crypt\DSA;
use phpseclib3\Crypt\Common;
use phpseclib3\Crypt\DSA;
use phpseclib3\Crypt\DSA\Formats\Signature\ASN1 as ASN1Signature;
use phpseclib3\Math\BigInteger;
/**
* DSA Private Key
*
* @author Jim Wigginton <terrafrost@php.net>
*/
final class PrivateKey extends DSA implements Common\PrivateKey
{
use Common\Traits\PasswordProtected;
/**
* DSA secret exponent x
*
* @var \phpseclib3\Math\BigInteger
*/
protected $x;
/**
* 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()
* @return mixed
*/
public function getPublicKey()
{
$type = self::validatePlugin('Keys', 'PKCS8', 'savePublicKey');
if (!isset($this->y)) {
$this->y = $this->g->powMod($this->x, $this->p);
}
$key = $type::savePublicKey($this->p, $this->q, $this->g, $this->y);
return DSA::loadFormat('PKCS8', $key)
->withHash($this->hash->getHash())
->withSignatureFormat($this->shortFormat);
}
/**
* Create a signature
*
* @see self::verify()
* @param string $message
* @return mixed
*/
public function sign($message)
{
$format = $this->sigFormat;
if (self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods())) {
$signature = '';
$result = openssl_sign($message, $signature, $this->toString('PKCS8'), $this->hash->getHash());
if ($result) {
if ($this->shortFormat == 'ASN1') {
return $signature;
}
extract(ASN1Signature::load($signature));
return $format::save($r, $s);
}
}
$h = $this->hash->hash($message);
$h = $this->bits2int($h);
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);
$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);
}
/**
* Returns the private key
*
* @param string $type
* @param array $options optional
* @return string
*/
public function toString($type, array $options = [])
{
$type = self::validatePlugin('Keys', $type, 'savePrivateKey');
if (!isset($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, $options);
}
}
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