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<?php
/**
* RSA 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\RSA;
use phpseclib3\Crypt\Common;
use phpseclib3\Crypt\Random;
use phpseclib3\Crypt\RSA;
use phpseclib3\Crypt\RSA\Formats\Keys\PSS;
use phpseclib3\Exception\UnsupportedFormatException;
use phpseclib3\Math\BigInteger;
/**
* Raw RSA Key Handler
*
* @author Jim Wigginton <terrafrost@php.net>
*/
final class PrivateKey extends RSA implements Common\PrivateKey
{
use Common\Traits\PasswordProtected;
/**
* Primes for Chinese Remainder Theorem (ie. p and q)
*
* @var array
*/
protected $primes;
/**
* Exponents for Chinese Remainder Theorem (ie. dP and dQ)
*
* @var array
*/
protected $exponents;
/**
* Coefficients for Chinese Remainder Theorem (ie. qInv)
*
* @var array
*/
protected $coefficients;
/**
* Private Exponent
*
* @var \phpseclib3\Math\BigInteger
*/
protected $privateExponent;
/**
* RSADP
*
* See {@link http://tools.ietf.org/html/rfc3447#section-5.1.2 RFC3447#section-5.1.2}.
*
* @return bool|\phpseclib3\Math\BigInteger
*/
private function rsadp(BigInteger $c)
{
if ($c->compare(self::$zero) < 0 || $c->compare($this->modulus) > 0) {
throw new \OutOfRangeException('Ciphertext representative out of range');
}
return $this->exponentiate($c);
}
/**
* RSASP1
*
* See {@link http://tools.ietf.org/html/rfc3447#section-5.2.1 RFC3447#section-5.2.1}.
*
* @return bool|\phpseclib3\Math\BigInteger
*/
private function rsasp1(BigInteger $m)
{
if ($m->compare(self::$zero) < 0 || $m->compare($this->modulus) > 0) {
throw new \OutOfRangeException('Signature representative out of range');
}
return $this->exponentiate($m);
}
/**
* Exponentiate
*
* @param \phpseclib3\Math\BigInteger $x
* @return \phpseclib3\Math\BigInteger
*/
protected function exponentiate(BigInteger $x)
{
switch (true) {
case empty($this->primes):
case $this->primes[1]->equals(self::$zero):
case empty($this->coefficients):
case $this->coefficients[2]->equals(self::$zero):
case empty($this->exponents):
case $this->exponents[1]->equals(self::$zero):
return $x->modPow($this->exponent, $this->modulus);
}
$num_primes = count($this->primes);
if (!static::$enableBlinding) {
$m_i = [
1 => $x->modPow($this->exponents[1], $this->primes[1]),
2 => $x->modPow($this->exponents[2], $this->primes[2])
];
$h = $m_i[1]->subtract($m_i[2]);
$h = $h->multiply($this->coefficients[2]);
list(, $h) = $h->divide($this->primes[1]);
$m = $m_i[2]->add($h->multiply($this->primes[2]));
$r = $this->primes[1];
for ($i = 3; $i <= $num_primes; $i++) {
$m_i = $x->modPow($this->exponents[$i], $this->primes[$i]);
$r = $r->multiply($this->primes[$i - 1]);
$h = $m_i->subtract($m);
$h = $h->multiply($this->coefficients[$i]);
list(, $h) = $h->divide($this->primes[$i]);
$m = $m->add($r->multiply($h));
}
} else {
$smallest = $this->primes[1];
for ($i = 2; $i <= $num_primes; $i++) {
if ($smallest->compare($this->primes[$i]) > 0) {
$smallest = $this->primes[$i];
}
}
$r = BigInteger::randomRange(self::$one, $smallest->subtract(self::$one));
$m_i = [
1 => $this->blind($x, $r, 1),
2 => $this->blind($x, $r, 2)
];
$h = $m_i[1]->subtract($m_i[2]);
$h = $h->multiply($this->coefficients[2]);
list(, $h) = $h->divide($this->primes[1]);
$m = $m_i[2]->add($h->multiply($this->primes[2]));
$r = $this->primes[1];
for ($i = 3; $i <= $num_primes; $i++) {
$m_i = $this->blind($x, $r, $i);
$r = $r->multiply($this->primes[$i - 1]);
$h = $m_i->subtract($m);
$h = $h->multiply($this->coefficients[$i]);
list(, $h) = $h->divide($this->primes[$i]);
$m = $m->add($r->multiply($h));
}
}
return $m;
}
/**
* Performs RSA Blinding
*
* Protects against timing attacks by employing RSA Blinding.
* Returns $x->modPow($this->exponents[$i], $this->primes[$i])
*
* @param \phpseclib3\Math\BigInteger $x
* @param \phpseclib3\Math\BigInteger $r
* @param int $i
* @return \phpseclib3\Math\BigInteger
*/
private function blind(BigInteger $x, BigInteger $r, $i)
{
$x = $x->multiply($r->modPow($this->publicExponent, $this->primes[$i]));
$x = $x->modPow($this->exponents[$i], $this->primes[$i]);
$r = $r->modInverse($this->primes[$i]);
$x = $x->multiply($r);
list(, $x) = $x->divide($this->primes[$i]);
return $x;
}
/**
* EMSA-PSS-ENCODE
*
* See {@link http://tools.ietf.org/html/rfc3447#section-9.1.1 RFC3447#section-9.1.1}.
*
* @return string
* @param string $m
* @throws \RuntimeException on encoding error
* @param int $emBits
*/
private function emsa_pss_encode($m, $emBits)
{
// if $m is larger than two million terrabytes and you're using sha1, PKCS#1 suggests a "Label too long" error
// be output.
$emLen = ($emBits + 1) >> 3; // ie. ceil($emBits / 8)
$sLen = $this->sLen !== null ? $this->sLen : $this->hLen;
$mHash = $this->hash->hash($m);
if ($emLen < $this->hLen + $sLen + 2) {
throw new \LengthException('RSA modulus too short');
}
$salt = Random::string($sLen);
$m2 = "\0\0\0\0\0\0\0\0" . $mHash . $salt;
$h = $this->hash->hash($m2);
$ps = str_repeat(chr(0), $emLen - $sLen - $this->hLen - 2);
$db = $ps . chr(1) . $salt;
$dbMask = $this->mgf1($h, $emLen - $this->hLen - 1); // ie. stlren($db)
$maskedDB = $db ^ $dbMask;
$maskedDB[0] = ~chr(0xFF << ($emBits & 7)) & $maskedDB[0];
$em = $maskedDB . $h . chr(0xBC);
return $em;
}
/**
* RSASSA-PSS-SIGN
*
* See {@link http://tools.ietf.org/html/rfc3447#section-8.1.1 RFC3447#section-8.1.1}.
*
* @param string $m
* @return bool|string
*/
private function rsassa_pss_sign($m)
{
// EMSA-PSS encoding
$em = $this->emsa_pss_encode($m, 8 * $this->k - 1);
// RSA signature
$m = $this->os2ip($em);
$s = $this->rsasp1($m);
$s = $this->i2osp($s, $this->k);
// Output the signature S
return $s;
}
/**
* RSASSA-PKCS1-V1_5-SIGN
*
* See {@link http://tools.ietf.org/html/rfc3447#section-8.2.1 RFC3447#section-8.2.1}.
*
* @param string $m
* @throws \LengthException if the RSA modulus is too short
* @return bool|string
*/
private function rsassa_pkcs1_v1_5_sign($m)
{
// EMSA-PKCS1-v1_5 encoding
// If the encoding operation outputs "intended encoded message length too short," output "RSA modulus
// too short" and stop.
try {
$em = $this->emsa_pkcs1_v1_5_encode($m, $this->k);
} catch (\LengthException $e) {
throw new \LengthException('RSA modulus too short');
}
// RSA signature
$m = $this->os2ip($em);
$s = $this->rsasp1($m);
$s = $this->i2osp($s, $this->k);
// Output the signature S
return $s;
}
/**
* Create a signature
*
* @see self::verify()
* @param string $message
* @return string
*/
public function sign($message)
{
switch ($this->signaturePadding) {
case self::SIGNATURE_PKCS1:
case self::SIGNATURE_RELAXED_PKCS1:
return $this->rsassa_pkcs1_v1_5_sign($message);
//case self::SIGNATURE_PSS:
default:
return $this->rsassa_pss_sign($message);
}
}
/**
* RSAES-PKCS1-V1_5-DECRYPT
*
* See {@link http://tools.ietf.org/html/rfc3447#section-7.2.2 RFC3447#section-7.2.2}.
*
* @param string $c
* @return bool|string
*/
private function rsaes_pkcs1_v1_5_decrypt($c)
{
// Length checking
if (strlen($c) != $this->k) { // or if k < 11
throw new \LengthException('Ciphertext representative too long');
}
// RSA decryption
$c = $this->os2ip($c);
$m = $this->rsadp($c);
$em = $this->i2osp($m, $this->k);
// EME-PKCS1-v1_5 decoding
if (ord($em[0]) != 0 || ord($em[1]) > 2) {
throw new \RuntimeException('Decryption error');
}
$ps = substr($em, 2, strpos($em, chr(0), 2) - 2);
$m = substr($em, strlen($ps) + 3);
if (strlen($ps) < 8) {
throw new \RuntimeException('Decryption error');
}
// Output M
return $m;
}
/**
* RSAES-OAEP-DECRYPT
*
* See {@link http://tools.ietf.org/html/rfc3447#section-7.1.2 RFC3447#section-7.1.2}. The fact that the error
* messages aren't distinguishable from one another hinders debugging, but, to quote from RFC3447#section-7.1.2:
*
* Note. Care must be taken to ensure that an opponent cannot
* distinguish the different error conditions in Step 3.g, whether by
* error message or timing, or, more generally, learn partial
* information about the encoded message EM. Otherwise an opponent may
* be able to obtain useful information about the decryption of the
* ciphertext C, leading to a chosen-ciphertext attack such as the one
* observed by Manger [36].
*
* @param string $c
* @return bool|string
*/
private function rsaes_oaep_decrypt($c)
{
// Length checking
// if $l is larger than two million terrabytes and you're using sha1, PKCS#1 suggests a "Label too long" error
// be output.
if (strlen($c) != $this->k || $this->k < 2 * $this->hLen + 2) {
throw new \LengthException('Ciphertext representative too long');
}
// RSA decryption
$c = $this->os2ip($c);
$m = $this->rsadp($c);
$em = $this->i2osp($m, $this->k);
// EME-OAEP decoding
$lHash = $this->hash->hash($this->label);
$y = ord($em[0]);
$maskedSeed = substr($em, 1, $this->hLen);
$maskedDB = substr($em, $this->hLen + 1);
$seedMask = $this->mgf1($maskedDB, $this->hLen);
$seed = $maskedSeed ^ $seedMask;
$dbMask = $this->mgf1($seed, $this->k - $this->hLen - 1);
$db = $maskedDB ^ $dbMask;
$lHash2 = substr($db, 0, $this->hLen);
$m = substr($db, $this->hLen);
$hashesMatch = hash_equals($lHash, $lHash2);
$leadingZeros = 1;
$patternMatch = 0;
$offset = 0;
for ($i = 0; $i < strlen($m); $i++) {
$patternMatch |= $leadingZeros & ($m[$i] === "\1");
$leadingZeros &= $m[$i] === "\0";
$offset += $patternMatch ? 0 : 1;
}
// we do | instead of || to avoid https://en.wikipedia.org/wiki/Short-circuit_evaluation
// to protect against timing attacks
if (!$hashesMatch | !$patternMatch) {
throw new \RuntimeException('Decryption error');
}
// Output the message M
return substr($m, $offset + 1);
}
/**
* Raw Encryption / Decryption
*
* Doesn't use padding and is not recommended.
*
* @param string $m
* @return bool|string
* @throws \LengthException if strlen($m) > $this->k
*/
private function raw_encrypt($m)
{
if (strlen($m) > $this->k) {
throw new \LengthException('Ciphertext representative too long');
}
$temp = $this->os2ip($m);
$temp = $this->rsadp($temp);
return $this->i2osp($temp, $this->k);
}
/**
* Decryption
*
* @see self::encrypt()
* @param string $ciphertext
* @return bool|string
*/
public function decrypt($ciphertext)
{
switch ($this->encryptionPadding) {
case self::ENCRYPTION_NONE:
return $this->raw_encrypt($ciphertext);
case self::ENCRYPTION_PKCS1:
return $this->rsaes_pkcs1_v1_5_decrypt($ciphertext);
//case self::ENCRYPTION_OAEP:
default:
return $this->rsaes_oaep_decrypt($ciphertext);
}
}
/**
* Returns the public key
*
* @return mixed
*/
public function getPublicKey()
{
$type = self::validatePlugin('Keys', 'PKCS8', 'savePublicKey');
if (empty($this->modulus) || empty($this->publicExponent)) {
throw new \RuntimeException('Public key components not found');
}
$key = $type::savePublicKey($this->modulus, $this->publicExponent);
return RSA::loadFormat('PKCS8', $key)
->withHash($this->hash->getHash())
->withMGFHash($this->mgfHash->getHash())
->withSaltLength($this->sLen)
->withLabel($this->label)
->withPadding($this->signaturePadding | $this->encryptionPadding);
}
/**
* Returns the private key
*
* @param string $type
* @param array $options optional
* @return string
*/
public function toString($type, array $options = [])
{
$type = self::validatePlugin(
'Keys',
$type,
empty($this->primes) ? 'savePublicKey' : 'savePrivateKey'
);
if ($type == PSS::class) {
if ($this->signaturePadding == self::SIGNATURE_PSS) {
$options += [
'hash' => $this->hash->getHash(),
'MGFHash' => $this->mgfHash->getHash(),
'saltLength' => $this->getSaltLength()
];
} else {
throw new UnsupportedFormatException('The PSS format can only be used when the signature method has been explicitly set to PSS');
}
}
if (empty($this->primes)) {
return $type::savePublicKey($this->modulus, $this->exponent, $options);
}
return $type::savePrivateKey($this->modulus, $this->publicExponent, $this->exponent, $this->primes, $this->exponents, $this->coefficients, $this->password, $options);
/*
$key = $type::savePrivateKey($this->modulus, $this->publicExponent, $this->exponent, $this->primes, $this->exponents, $this->coefficients, $this->password, $options);
if ($key !== false || count($this->primes) == 2) {
return $key;
}
$nSize = $this->getSize() >> 1;
$primes = [1 => clone self::$one, clone self::$one];
$i = 1;
foreach ($this->primes as $prime) {
$primes[$i] = $primes[$i]->multiply($prime);
if ($primes[$i]->getLength() >= $nSize) {
$i++;
}
}
$exponents = [];
$coefficients = [2 => $primes[2]->modInverse($primes[1])];
foreach ($primes as $i => $prime) {
$temp = $prime->subtract(self::$one);
$exponents[$i] = $this->modulus->modInverse($temp);
}
return $type::savePrivateKey($this->modulus, $this->publicExponent, $this->exponent, $primes, $exponents, $coefficients, $this->password, $options);
*/
}
}
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