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tgseclib/phpseclib/Crypt/ECDSA.php

756 lines
23 KiB
PHP

<?php
/**
* Pure-PHP implementation of ECDSA.
*
* 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\ECDSA::createKey());
*
* $plaintext = 'terrafrost';
*
* $signature = $privatekey->sign($plaintext, 'ASN1');
*
* echo $publickey->verify($plaintext, $signature) ? 'verified' : 'unverified';
* ?>
* </code>
*
* @category Crypt
* @package ECDSA
* @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 phpseclib\Math\BigInteger;
use phpseclib\Crypt\Common\AsymmetricKey;
use phpseclib\Exception\UnsupportedCurveException;
use phpseclib\Exception\UnsupportedOperationException;
use phpseclib\Exception\NoKeyLoadedException;
use phpseclib\File\ASN1;
use phpseclib\File\ASN1\Maps\ECParameters;
use phpseclib\Crypt\ECDSA\BaseCurves\TwistedEdwards as TwistedEdwardsCurve;
use phpseclib\Crypt\ECDSA\Curves\Ed25519;
use phpseclib\Crypt\ECDSA\Curves\Ed448;
use phpseclib\Crypt\ECDSA\Keys\PKCS1;
use phpseclib\Crypt\ECDSA\Keys\PKCS8;
use phpseclib\Crypt\ECDSA\Signature\ASN1 as ASN1Signature;
/**
* Pure-PHP implementation of ECDSA.
*
* @package ECDSA
* @author Jim Wigginton <terrafrost@php.net>
* @access public
*/
class ECDSA extends AsymmetricKey
{
/**
* Algorithm Name
*
* @var string
* @access private
*/
const ALGORITHM = 'ECDSA';
/**
* 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
*/
private $dA;
/**
* Public Key QA
*
* @var object[]
*/
private $QA;
/**
* Curve
*
* @var \phpseclib\Crypt\ECDSA\BaseCurves\Base
*/
private $curve;
/**
* Curve Name
*
* @var string
*/
private $curveName;
/**
* Curve Order
*
* Used for deterministic ECDSA
*
* @var \phpseclib\Math\BigInteger
*/
protected $q;
/**
* Alias for the private key
*
* Used for deterministic ECDSA. AsymmetricKey expects $x. I don't like x because
* with x you have x * the base point yielding an (x, y)-coordinate that is the
* public key. But the x is different depending on which side of the equal sign
* you're on. It's less ambiguous if you do dA * base point = (x, y)-coordinate.
*
* @var \phpseclib\Math\BigInteger
*/
protected $x;
/**
* Alias for the private key
*
* Used for deterministic ECDSA. AsymmetricKey expects $x. I don't like x because
* with x you have x * the base point yielding an (x, y)-coordinate that is the
* public key. But the x is different depending on which side of the equal sign
* you're on. It's less ambiguous if you do dA * base point = (x, y)-coordinate.
*
* @var \phpseclib\Math\BigInteger
*/
private $context;
/**
* Create public / private key pair.
*
* @access public
* @param string $curve
* @return \phpseclib\Crypt\ECDSA[]
*/
public static function createKey($curve)
{
self::initialize_static_variables();
if (!isset(self::$engines['PHP'])) {
self::useBestEngine();
}
if (self::$engines['libsodium'] && $curve == 'Ed25519' && function_exists('sodium_crypto_sign_keypair')) {
$kp = sodium_crypto_sign_keypair();
$privatekey = new static();
$privatekey->load(sodium_crypto_sign_secretkey($kp));
$publickey = new static();
$publickey->load(sodium_crypto_sign_publickey($kp));
$publickey->curveName = $privatekey->curveName = $curve;
return compact('privatekey', 'publickey');
}
$privatekey = new static();
$curveName = $curve;
$curve = '\phpseclib\Crypt\ECDSA\Curves\\' . $curve;
if (!class_exists($curve)) {
throw new UnsupportedCurveException('Named Curve of ' . $curve . ' is not supported');
}
$curve = new $curve();
$privatekey->dA = $dA = $curve->createRandomMultiplier();
$privatekey->QA = $curve->multiplyPoint($curve->getBasePoint(), $dA);
$privatekey->curve = $curve;
$publickey = clone $privatekey;
unset($publickey->dA);
unset($publickey->x);
$publickey->curveName = $privatekey->curveName = $curveName;
return compact('privatekey', 'publickey');
}
/**
* 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, $type = false)
{
self::initialize_static_variables();
if (!isset(self::$engines['PHP'])) {
self::useBestEngine();
}
if ($key instanceof ECDSA) {
$this->privateKeyFormat = $key->privateKeyFormat;
$this->publicKeyFormat = $key->publicKeyFormat;
$this->format = $key->format;
$this->dA = isset($key->dA) ? $key->dA : null;
$this->QA = $key->QA;
$this->curve = $key->curve;
$this->parametersFormat = $key->parametersFormat;
$this->hash = $key->hash;
parent::load($key, false);
return true;
}
$components = parent::load($key, $type);
if ($components === false) {
$this->clearKey();
return false;
}
if ($components['curve'] instanceof Ed25519 && $this->hashManuallySet && $this->hash->getHash() != 'sha512') {
$this->clearKey();
throw new \RuntimeException('Ed25519 only supports sha512 as a hash');
}
if ($components['curve'] instanceof Ed448 && $this->hashManuallySet && $this->hash->getHash() != 'shake256-912') {
$this->clearKey();
throw new \RuntimeException('Ed448 only supports shake256 with a length of 114 bytes');
}
$this->curve = $components['curve'];
$this->QA = $components['QA'];
$this->dA = isset($components['dA']) ? $components['dA'] : null;
return true;
}
/**
* Removes a key
*
* @access private
*/
private function clearKey()
{
$this->format = null;
$this->dA = null;
$this->QA = null;
$this->curve = null;
}
/**
* Returns the curve
*
* Returns a string if it's a named curve, an array if not
*
* @access public
* @return string|array
*/
public function getCurve()
{
if ($this->curveName) {
return $this->curveName;
}
if ($this->curve instanceof TwistedEdwardsCurve) {
$this->curveName = $this->curve instanceof Ed25519 ? 'Ed25519' : 'Ed448';
return $this->curveName;
}
$namedCurves = PKCS1::isUsingNamedCurves();
PKCS1::useNamedCurve();
$params = $this->getParameters();
$decoded = ASN1::extractBER($params);
$decoded = ASN1::decodeBER($decoded);
$decoded = ASN1::asn1map($decoded[0], ECParameters::MAP);
if (isset($decoded['namedCurve'])) {
$this->curveName = $decoded['namedCurve'];
if (!$namedCurves) {
PKCS1::useSpecifiedCurve();
}
return $decoded['namedCurve'];
}
if (!$namedCurves) {
PKCS1::useSpecifiedCurve();
}
return $decoded;
}
/**
* Returns the key size
*
* Quoting https://tools.ietf.org/html/rfc5656#section-2,
*
* "The size of a set of elliptic curve domain parameters on a prime
* curve is defined as the number of bits in the binary representation
* of the field order, commonly denoted by p. Size on a
* characteristic-2 curve is defined as the number of bits in the binary
* representation of the field, commonly denoted by m. A set of
* elliptic curve domain parameters defines a group of order n generated
* by a base point P"
*
* @access public
* @return int
*/
public function getLength()
{
if (!isset($this->QA)) {
return 0;
}
return $this->curve->getLength();
}
/**
* Is the key a private key?
*
* @access public
* @return bool
*/
public function isPrivateKey()
{
return isset($this->dA);
}
/**
* Is the key a public key?
*
* @access public
* @return bool
*/
public function isPublicKey()
{
return isset($this->QA);
}
/**
* Returns the private key
*
* @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->dA)) {
return false;
}
return $type::savePrivateKey($this->dA, $this->curve, $this->QA, $this->password);
}
/**
* Returns the public key
*
* @see self::getPrivateKey()
* @access public
* @param string $type optional
* @return mixed
*/
public function getPublicKey($type = null)
{
$returnObj = false;
if ($type === null) {
$returnObj = true;
$type = 'PKCS8';
}
$type = self::validatePlugin('Keys', $type, 'savePublicKey');
if ($type === false) {
return false;
}
if (!isset($this->QA)) {
return false;
}
$key = $type::savePublicKey($this->curve, $this->QA);
if ($returnObj) {
$public = clone $this;
$public->load($key, 'PKCS8');
return $public;
}
return $key;
}
/**
* 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->curve) || $this->curve instanceof TwistedEdwardsCurve) {
return false;
}
return $type::saveParameters($this->curve);
}
/**
* Returns the current engine being used
*
* @see self::useInternalEngine()
* @see self::useBestEngine()
* @access public
* @return string
*/
public function getEngine()
{
if (!isset($this->curve)) {
throw new \RuntimeException('getEngine should not be called until after a key has been loaded');
}
if ($this->curve instanceof TwistedEdwardsCurve) {
return $this->curve instanceof Ed25519 && self::$engines['libsodium'] && !isset($this->context) ?
'libsodium' : 'PHP';
}
return self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods()) ?
'OpenSSL' : 'PHP';
}
/**
* Sets the context
*
* Used by Ed25519 / Ed448.
*
* @see self::sign()
* @see self::verify()
* @access public
* @param string $context optional
*/
public function setContext($context = null)
{
if (!isset($context)) {
$this->context = null;
return;
}
if (!is_string($context)) {
throw new \RuntimeException('setContext expects a string');
}
if (strlen($context) > 255) {
throw new \RuntimeException('The context is supposed to be, at most, 255 bytes long');
}
$this->context = $context;
}
/**
* Determines which hashing function should be used
*
* @access public
* @param string $hash
*/
public function setHash($hash)
{
if ($this->curve instanceof Ed25519 && $this->hash != 'sha512') {
throw new \RuntimeException('Ed25519 only supports sha512 as a hash');
}
if ($this->curve instanceof Ed448 && $this->hash != 'shake256-912') {
throw new \RuntimeException('Ed448 only supports shake256 with a length of 114 bytes');
}
parent::setHash($hash);
}
/**
* Create a signature
*
* @see self::verify()
* @access public
* @param string $message
* @param string $format optional
* @return mixed
*/
public function sign($message, $format = 'ASN1')
{
if (!isset($this->dA)) {
if (!isset($this->QA)) {
throw new NoKeyLoadedException('No key has been loaded');
}
throw new UnsupportedOperationException('A public key cannot be used to sign data');
}
$dA = $this->dA->toBigInteger();
$order = $this->curve->getOrder();
if ($this->curve instanceof TwistedEdwardsCurve) {
if ($this->curve instanceof Ed25519 && self::$engines['libsodium'] && !isset($this->context)) {
return sodium_crypto_sign_detached($message, $this->getPrivateKey('libsodium'));
}
// 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->dA->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(), $curve->convertInteger($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 $R . $S;
}
$shortFormat = $format;
$format = self::validatePlugin('Signature', $format);
if ($format === false) {
return false;
}
if (self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods())) {
$namedCurves = PKCS8::isUsingNamedCurves();
// 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
PKCS8::useSpecifiedCurve();
$signature = '';
// altho PHP's OpenSSL bindings only supported ECDSA key creation in PHP 7.1 they've long
// supported signing / verification
$result = openssl_sign($message, $signature, $this->getPrivateKey(), $this->hash->getHash());
if ($namedCurves) {
PKCS8::useNamedCurve();
}
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(), $this->curve->convertInteger($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(), $this->curve->convertInteger($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);
}
/**
* Verify a signature
*
* @see self::verify()
* @access public
* @param string $message
* @param string $format optional
* @return mixed
*/
public function verify($message, $signature, $format = 'ASN1')
{
if (!isset($this->QA)) {
if (!isset($this->dA)) {
throw new NoKeyLoadedException('No key has been loaded');
}
throw new UnsupportedOperationException('A private key cannot be used to verify data');
}
$order = $this->curve->getOrder();
if ($this->curve instanceof TwistedEdwardsCurve) {
if ($this->curve instanceof Ed25519 && self::$engines['libsodium'] && !isset($this->context)) {
return sodium_crypto_sign_verify_detached($signature, $message, $this->getPublicKey('libsodium'));
}
$curve = $this->curve;
if (strlen($signature) != 2 * $curve::SIZE) {
return false;
}
$R = substr($signature, 0, $curve::SIZE);
$S = substr($signature, $curve::SIZE);
try {
$R = PKCS1::extractPoint($R, $curve);
$R = $this->curve->convertToInternal($R);
} catch (\Exception $e) {
return false;
}
$S = strrev($S);
$S = new BigInteger($S, 256);
if ($S->compare($order) >= 0) {
return false;
}
$A = $curve->encodePoint($this->QA);
if ($curve instanceof Ed25519) {
$dom2 = !isset($this->context) ? '' :
'SigEd25519 no Ed25519 collisions' . "\0" . chr(strlen($this->context)) . $this->context;
} else {
$context = isset($this->context) ? $this->context : '';
$dom2 = 'SigEd448' . "\0" . chr(strlen($context)) . $context;
}
$hash = new Hash($curve::HASH);
$k = $hash->hash($dom2 . substr($signature, 0, $curve::SIZE) . $A . $message);
$k = strrev($k);
$k = new BigInteger($k, 256);
list(, $k) = $k->divide($order);
$qa = $curve->convertToInternal($this->QA);
$lhs = $curve->multiplyPoint($curve->getBasePoint(), $curve->convertInteger($S));
$rhs = $curve->multiplyPoint($qa, $curve->convertInteger($k));
$rhs = $curve->addPoint($rhs, $R);
$rhs = $curve->convertToAffine($rhs);
return $lhs[0]->equals($rhs[0]) && $lhs[1]->equals($rhs[1]);
}
$format = self::validatePlugin('Signature', $format);
if ($format === false) {
return false;
}
$params = $format::load($signature);
if ($params === false || count($params) != 2) {
return false;
}
extract($params);
if (self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods())) {
$namedCurves = PKCS8::isUsingNamedCurves();
PKCS8::useSpecifiedCurve();
$sig = $format != 'ASN1' ? ASN1Signature::save($r, $s) : $signature;
$result = openssl_verify($message, $sig, $this->getPublicKey(), $this->hash->getHash());
if ($namedCurves) {
PKCS8::useNamedCurve();
}
if ($result != -1) {
return (bool) $result;
}
}
$n_1 = $order->subtract(self::$one);
if (!$r->between(self::$one, $n_1) || !$s->between(self::$one, $n_1)) {
return false;
}
$e = $this->hash->hash($message);
$e = new BigInteger($e, 256);
$Ln = $this->hash->getLength() - $order->getLength();
$z = $Ln > 0 ? $e->bitwise_rightShift($Ln) : $e;
$w = $s->modInverse($order);
list(, $u1) = $z->multiply($w)->divide($order);
list(, $u2) = $r->multiply($w)->divide($order);
$u1 = $this->curve->convertInteger($u1);
$u2 = $this->curve->convertInteger($u2);
list($x1, $y1) = $this->curve->multiplyAddPoints(
[$this->curve->getBasePoint(), $this->QA],
[$u1, $u2]
);
$x1 = $x1->toBigInteger();
list(, $x1) = $x1->divide($order);
return $x1->equals($r);
}
}