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<?php
/**
* EC 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\EC;
use phpseclib3\Common\Functions\Strings;
use phpseclib3\Crypt\Common;
use phpseclib3\Crypt\EC;
use phpseclib3\Crypt\EC\BaseCurves\Montgomery as MontgomeryCurve;
use phpseclib3\Crypt\EC\BaseCurves\TwistedEdwards as TwistedEdwardsCurve;
use phpseclib3\Crypt\EC\Curves\Curve25519;
use phpseclib3\Crypt\EC\Curves\Ed25519;
use phpseclib3\Crypt\EC\Formats\Keys\PKCS1;
use phpseclib3\Crypt\EC\Formats\Signature\ASN1 as ASN1Signature;
use phpseclib3\Crypt\Hash;
use phpseclib3\Exception\UnsupportedOperationException;
use phpseclib3\Math\BigInteger;
/**
* EC Private Key
*
* @author Jim Wigginton <terrafrost@php.net>
*/
final class PrivateKey extends EC implements Common\PrivateKey
{
use Common\Traits\PasswordProtected;
/**
* Private Key dA
*
* sign() converts this to a BigInteger so one might wonder why this is a FiniteFieldInteger instead of
* a BigInteger. That's because a FiniteFieldInteger, when converted to a byte string, is null padded by
* a certain amount whereas a BigInteger isn't.
*
* @var object
*/
protected $dA;
/**
* @var string
*/
protected $secret;
/**
* Multiplies an encoded point by the private key
*
* Used by ECDH
*
* @param string $coordinates
* @return string
*/
public function multiply($coordinates)
{
if ($this->curve instanceof MontgomeryCurve) {
if ($this->curve instanceof Curve25519 && self::$engines['libsodium']) {
return sodium_crypto_scalarmult($this->dA->toBytes(), $coordinates);
}
$point = [$this->curve->convertInteger(new BigInteger(strrev($coordinates), 256))];
$point = $this->curve->multiplyPoint($point, $this->dA);
return strrev($point[0]->toBytes(true));
}
if (!$this->curve instanceof TwistedEdwardsCurve) {
$coordinates = "\0$coordinates";
}
$point = PKCS1::extractPoint($coordinates, $this->curve);
$point = $this->curve->multiplyPoint($point, $this->dA);
if ($this->curve instanceof TwistedEdwardsCurve) {
return $this->curve->encodePoint($point);
}
if (empty($point)) {
throw new \RuntimeException('The infinity point is invalid');
}
return "\4" . $point[0]->toBytes(true) . $point[1]->toBytes(true);
}
/**
* Create a signature
*
* @see self::verify()
* @param string $message
* @return mixed
*/
public function sign($message)
{
if ($this->curve instanceof MontgomeryCurve) {
throw new UnsupportedOperationException('Montgomery Curves cannot be used to create signatures');
}
$dA = $this->dA;
$order = $this->curve->getOrder();
$shortFormat = $this->shortFormat;
$format = $this->sigFormat;
if ($format === false) {
return false;
}
if ($this->curve instanceof TwistedEdwardsCurve) {
if ($this->curve instanceof Ed25519 && self::$engines['libsodium'] && !isset($this->context)) {
$result = sodium_crypto_sign_detached($message, $this->withPassword()->toString('libsodium'));
return $shortFormat == 'SSH2' ? Strings::packSSH2('ss', 'ssh-' . strtolower($this->getCurve()), $result) : $result;
}
// contexts (Ed25519ctx) are supported but prehashing (Ed25519ph) is not.
// quoting https://tools.ietf.org/html/rfc8032#section-8.5 ,
// "The Ed25519ph and Ed448ph variants ... SHOULD NOT be used"
$A = $this->curve->encodePoint($this->QA);
$curve = $this->curve;
$hash = new Hash($curve::HASH);
$secret = substr($hash->hash($this->secret), $curve::SIZE);
if ($curve instanceof Ed25519) {
$dom = !isset($this->context) ? '' :
'SigEd25519 no Ed25519 collisions' . "\0" . chr(strlen($this->context)) . $this->context;
} else {
$context = isset($this->context) ? $this->context : '';
$dom = 'SigEd448' . "\0" . chr(strlen($context)) . $context;
}
// SHA-512(dom2(F, C) || prefix || PH(M))
$r = $hash->hash($dom . $secret . $message);
$r = strrev($r);
$r = new BigInteger($r, 256);
list(, $r) = $r->divide($order);
$R = $curve->multiplyPoint($curve->getBasePoint(), $r);
$R = $curve->encodePoint($R);
$k = $hash->hash($dom . $R . $A . $message);
$k = strrev($k);
$k = new BigInteger($k, 256);
list(, $k) = $k->divide($order);
$S = $k->multiply($dA)->add($r);
list(, $S) = $S->divide($order);
$S = str_pad(strrev($S->toBytes()), $curve::SIZE, "\0");
return $shortFormat == 'SSH2' ? Strings::packSSH2('ss', 'ssh-' . strtolower($this->getCurve()), $R . $S) : $R . $S;
}
if (self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods())) {
$signature = '';
// altho PHP's OpenSSL bindings only supported EC key creation in PHP 7.1 they've long
// supported signing / verification
// we use specified curves to avoid issues with OpenSSL possibly not supporting a given named curve;
// doing this may mean some curve-specific optimizations can't be used but idk if OpenSSL even
// has curve-specific optimizations
$result = openssl_sign($message, $signature, $this->toString('PKCS8', ['namedCurve' => false]), $this->hash->getHash());
if ($result) {
if ($shortFormat == 'ASN1') {
return $signature;
}
extract(ASN1Signature::load($signature));
return $shortFormat == 'SSH2' ? $format::save($r, $s, $this->getCurve()) : $format::save($r, $s);
}
}
$e = $this->hash->hash($message);
$e = new BigInteger($e, 256);
$Ln = $this->hash->getLength() - $order->getLength();
$z = $Ln > 0 ? $e->bitwise_rightShift($Ln) : $e;
while (true) {
$k = BigInteger::randomRange(self::$one, $order->subtract(self::$one));
list($x, $y) = $this->curve->multiplyPoint($this->curve->getBasePoint(), $k);
$x = $x->toBigInteger();
list(, $r) = $x->divide($order);
if ($r->equals(self::$zero)) {
continue;
}
$kinv = $k->modInverse($order);
$temp = $z->add($dA->multiply($r));
$temp = $kinv->multiply($temp);
list(, $s) = $temp->divide($order);
if (!$s->equals(self::$zero)) {
break;
}
}
// the following is an RFC6979 compliant implementation of deterministic ECDSA
// 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
/*
// if this were actually being used it'd probably be better if this lived in load() and createKey()
$this->q = $this->curve->getOrder();
$dA = $this->dA->toBigInteger();
$this->x = $dA;
$h1 = $this->hash->hash($message);
$k = $this->computek($h1);
list($x, $y) = $this->curve->multiplyPoint($this->curve->getBasePoint(), $k);
$x = $x->toBigInteger();
list(, $r) = $x->divide($this->q);
$kinv = $k->modInverse($this->q);
$h1 = $this->bits2int($h1);
$temp = $h1->add($dA->multiply($r));
$temp = $kinv->multiply($temp);
list(, $s) = $temp->divide($this->q);
*/
return $shortFormat == 'SSH2' ? $format::save($r, $s, $this->getCurve()) : $format::save($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');
return $type::savePrivateKey($this->dA, $this->curve, $this->QA, $this->secret, $this->password, $options);
}
/**
* Returns the public key
*
* @see self::getPrivateKey()
* @return mixed
*/
public function getPublicKey()
{
$format = 'PKCS8';
if ($this->curve instanceof MontgomeryCurve) {
$format = 'MontgomeryPublic';
}
$type = self::validatePlugin('Keys', $format, 'savePublicKey');
$key = $type::savePublicKey($this->curve, $this->QA);
$key = EC::loadFormat($format, $key);
if ($this->curve instanceof MontgomeryCurve) {
return $key;
}
$key = $key
->withHash($this->hash->getHash())
->withSignatureFormat($this->shortFormat);
if ($this->curve instanceof TwistedEdwardsCurve) {
$key = $key->withContext($this->context);
}
return $key;
}
}
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