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<?php
/**
* RSA Public 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\Common\Functions\Strings;
use phpseclib3\Crypt\Common;
use phpseclib3\Crypt\Hash;
use phpseclib3\Crypt\Random;
use phpseclib3\Crypt\RSA;
use phpseclib3\Crypt\RSA\Formats\Keys\PSS;
use phpseclib3\Exception\UnsupportedAlgorithmException;
use phpseclib3\Exception\UnsupportedFormatException;
use phpseclib3\File\ASN1;
use phpseclib3\File\ASN1\Maps\DigestInfo;
use phpseclib3\Math\BigInteger;
/**
* Raw RSA Key Handler
*
* @author Jim Wigginton <terrafrost@php.net>
*/
final class PublicKey extends RSA implements Common\PublicKey
{
use Common\Traits\Fingerprint;
/**
* Exponentiate
*
* @param \phpseclib3\Math\BigInteger $x
* @return \phpseclib3\Math\BigInteger
*/
private function exponentiate(BigInteger $x)
{
return $x->modPow($this->exponent, $this->modulus);
}
/**
* RSAVP1
*
* See {@link http://tools.ietf.org/html/rfc3447#section-5.2.2 RFC3447#section-5.2.2}.
*
* @param \phpseclib3\Math\BigInteger $s
* @return bool|\phpseclib3\Math\BigInteger
*/
private function rsavp1($s)
{
if ($s->compare(self::$zero) < 0 || $s->compare($this->modulus) > 0) {
return false;
}
return $this->exponentiate($s);
}
/**
* RSASSA-PKCS1-V1_5-VERIFY
*
* See {@link http://tools.ietf.org/html/rfc3447#section-8.2.2 RFC3447#section-8.2.2}.
*
* @param string $m
* @param string $s
* @throws \LengthException if the RSA modulus is too short
* @return bool
*/
private function rsassa_pkcs1_v1_5_verify($m, $s)
{
// Length checking
if (strlen($s) != $this->k) {
return false;
}
// RSA verification
$s = $this->os2ip($s);
$m2 = $this->rsavp1($s);
if ($m2 === false) {
return false;
}
$em = $this->i2osp($m2, $this->k);
if ($em === false) {
return false;
}
// EMSA-PKCS1-v1_5 encoding
$exception = false;
// If the encoding operation outputs "intended encoded message length too short," output "RSA modulus
// too short" and stop.
try {
$em2 = $this->emsa_pkcs1_v1_5_encode($m, $this->k);
$r1 = hash_equals($em, $em2);
} catch (\LengthException $e) {
$exception = true;
}
try {
$em3 = $this->emsa_pkcs1_v1_5_encode_without_null($m, $this->k);
$r2 = hash_equals($em, $em3);
} catch (\LengthException $e) {
$exception = true;
} catch (UnsupportedAlgorithmException $e) {
$r2 = false;
}
if ($exception) {
throw new \LengthException('RSA modulus too short');
}
// Compare
return $r1 || $r2;
}
/**
* RSASSA-PKCS1-V1_5-VERIFY (relaxed matching)
*
* Per {@link http://tools.ietf.org/html/rfc3447#page-43 RFC3447#page-43} PKCS1 v1.5
* specified the use BER encoding rather than DER encoding that PKCS1 v2.0 specified.
* This means that under rare conditions you can have a perfectly valid v1.5 signature
* that fails to validate with _rsassa_pkcs1_v1_5_verify(). PKCS1 v2.1 also recommends
* that if you're going to validate these types of signatures you "should indicate
* whether the underlying BER encoding is a DER encoding and hence whether the signature
* is valid with respect to the specification given in [PKCS1 v2.0+]". so if you do
* $rsa->getLastPadding() and get RSA::PADDING_RELAXED_PKCS1 back instead of
* RSA::PADDING_PKCS1... that means BER encoding was used.
*
* @param string $m
* @param string $s
* @return bool
*/
private function rsassa_pkcs1_v1_5_relaxed_verify($m, $s)
{
// Length checking
if (strlen($s) != $this->k) {
return false;
}
// RSA verification
$s = $this->os2ip($s);
$m2 = $this->rsavp1($s);
if ($m2 === false) {
return false;
}
$em = $this->i2osp($m2, $this->k);
if ($em === false) {
return false;
}
if (Strings::shift($em, 2) != "\0\1") {
return false;
}
$em = ltrim($em, "\xFF");
if (Strings::shift($em) != "\0") {
return false;
}
$decoded = ASN1::decodeBER($em);
if (!is_array($decoded) || empty($decoded[0]) || strlen($em) > $decoded[0]['length']) {
return false;
}
static $oids;
if (!isset($oids)) {
$oids = [
'md2' => '1.2.840.113549.2.2',
'md4' => '1.2.840.113549.2.4', // from PKCS1 v1.5
'md5' => '1.2.840.113549.2.5',
'id-sha1' => '1.3.14.3.2.26',
'id-sha256' => '2.16.840.1.101.3.4.2.1',
'id-sha384' => '2.16.840.1.101.3.4.2.2',
'id-sha512' => '2.16.840.1.101.3.4.2.3',
// from PKCS1 v2.2
'id-sha224' => '2.16.840.1.101.3.4.2.4',
'id-sha512/224' => '2.16.840.1.101.3.4.2.5',
'id-sha512/256' => '2.16.840.1.101.3.4.2.6',
];
ASN1::loadOIDs($oids);
}
$decoded = ASN1::asn1map($decoded[0], DigestInfo::MAP);
if (!isset($decoded) || $decoded === false) {
return false;
}
if (!isset($oids[$decoded['digestAlgorithm']['algorithm']])) {
return false;
}
if (isset($decoded['digestAlgorithm']['parameters']) && $decoded['digestAlgorithm']['parameters'] !== ['null' => '']) {
return false;
}
$hash = $decoded['digestAlgorithm']['algorithm'];
$hash = substr($hash, 0, 3) == 'id-' ?
substr($hash, 3) :
$hash;
$hash = new Hash($hash);
$em = $hash->hash($m);
$em2 = $decoded['digest'];
return hash_equals($em, $em2);
}
/**
* EMSA-PSS-VERIFY
*
* See {@link http://tools.ietf.org/html/rfc3447#section-9.1.2 RFC3447#section-9.1.2}.
*
* @param string $m
* @param string $em
* @param int $emBits
* @return string
*/
private function emsa_pss_verify($m, $em, $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 + 7) >> 3; // ie. ceil($emBits / 8);
$sLen = $this->sLen !== null ? $this->sLen : $this->hLen;
$mHash = $this->hash->hash($m);
if ($emLen < $this->hLen + $sLen + 2) {
return false;
}
if ($em[strlen($em) - 1] != chr(0xBC)) {
return false;
}
$maskedDB = substr($em, 0, -$this->hLen - 1);
$h = substr($em, -$this->hLen - 1, $this->hLen);
$temp = chr(0xFF << ($emBits & 7));
if ((~$maskedDB[0] & $temp) != $temp) {
return false;
}
$dbMask = $this->mgf1($h, $emLen - $this->hLen - 1);
$db = $maskedDB ^ $dbMask;
$db[0] = ~chr(0xFF << ($emBits & 7)) & $db[0];
$temp = $emLen - $this->hLen - $sLen - 2;
if (substr($db, 0, $temp) != str_repeat(chr(0), $temp) || ord($db[$temp]) != 1) {
return false;
}
$salt = substr($db, $temp + 1); // should be $sLen long
$m2 = "\0\0\0\0\0\0\0\0" . $mHash . $salt;
$h2 = $this->hash->hash($m2);
return hash_equals($h, $h2);
}
/**
* RSASSA-PSS-VERIFY
*
* See {@link http://tools.ietf.org/html/rfc3447#section-8.1.2 RFC3447#section-8.1.2}.
*
* @param string $m
* @param string $s
* @return bool|string
*/
private function rsassa_pss_verify($m, $s)
{
// Length checking
if (strlen($s) != $this->k) {
return false;
}
// RSA verification
$modBits = strlen($this->modulus->toBits());
$s2 = $this->os2ip($s);
$m2 = $this->rsavp1($s2);
$em = $this->i2osp($m2, $this->k);
if ($em === false) {
return false;
}
// EMSA-PSS verification
return $this->emsa_pss_verify($m, $em, $modBits - 1);
}
/**
* Verifies a signature
*
* @see self::sign()
* @param string $message
* @param string $signature
* @return bool
*/
public function verify($message, $signature)
{
switch ($this->signaturePadding) {
case self::SIGNATURE_RELAXED_PKCS1:
return $this->rsassa_pkcs1_v1_5_relaxed_verify($message, $signature);
case self::SIGNATURE_PKCS1:
return $this->rsassa_pkcs1_v1_5_verify($message, $signature);
//case self::SIGNATURE_PSS:
default:
return $this->rsassa_pss_verify($message, $signature);
}
}
/**
* RSAES-PKCS1-V1_5-ENCRYPT
*
* See {@link http://tools.ietf.org/html/rfc3447#section-7.2.1 RFC3447#section-7.2.1}.
*
* @param string $m
* @param bool $pkcs15_compat optional
* @throws \LengthException if strlen($m) > $this->k - 11
* @return bool|string
*/
private function rsaes_pkcs1_v1_5_encrypt($m, $pkcs15_compat = false)
{
$mLen = strlen($m);
// Length checking
if ($mLen > $this->k - 11) {
throw new \LengthException('Message too long');
}
// EME-PKCS1-v1_5 encoding
$psLen = $this->k - $mLen - 3;
$ps = '';
while (strlen($ps) != $psLen) {
$temp = Random::string($psLen - strlen($ps));
$temp = str_replace("\x00", '', $temp);
$ps .= $temp;
}
$type = 2;
$em = chr(0) . chr($type) . $ps . chr(0) . $m;
// RSA encryption
$m = $this->os2ip($em);
$c = $this->rsaep($m);
$c = $this->i2osp($c, $this->k);
// Output the ciphertext C
return $c;
}
/**
* RSAES-OAEP-ENCRYPT
*
* See {@link http://tools.ietf.org/html/rfc3447#section-7.1.1 RFC3447#section-7.1.1} and
* {http://en.wikipedia.org/wiki/Optimal_Asymmetric_Encryption_Padding OAES}.
*
* @param string $m
* @throws \LengthException if strlen($m) > $this->k - 2 * $this->hLen - 2
* @return string
*/
private function rsaes_oaep_encrypt($m)
{
$mLen = strlen($m);
// Length checking
// if $l is larger than two million terrabytes and you're using sha1, PKCS#1 suggests a "Label too long" error
// be output.
if ($mLen > $this->k - 2 * $this->hLen - 2) {
throw new \LengthException('Message too long');
}
// EME-OAEP encoding
$lHash = $this->hash->hash($this->label);
$ps = str_repeat(chr(0), $this->k - $mLen - 2 * $this->hLen - 2);
$db = $lHash . $ps . chr(1) . $m;
$seed = Random::string($this->hLen);
$dbMask = $this->mgf1($seed, $this->k - $this->hLen - 1);
$maskedDB = $db ^ $dbMask;
$seedMask = $this->mgf1($maskedDB, $this->hLen);
$maskedSeed = $seed ^ $seedMask;
$em = chr(0) . $maskedSeed . $maskedDB;
// RSA encryption
$m = $this->os2ip($em);
$c = $this->rsaep($m);
$c = $this->i2osp($c, $this->k);
// Output the ciphertext C
return $c;
}
/**
* RSAEP
*
* See {@link http://tools.ietf.org/html/rfc3447#section-5.1.1 RFC3447#section-5.1.1}.
*
* @param \phpseclib3\Math\BigInteger $m
* @return bool|\phpseclib3\Math\BigInteger
*/
private function rsaep($m)
{
if ($m->compare(self::$zero) < 0 || $m->compare($this->modulus) > 0) {
throw new \OutOfRangeException('Message representative out of range');
}
return $this->exponentiate($m);
}
/**
* 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('Message too long');
}
$temp = $this->os2ip($m);
$temp = $this->rsaep($temp);
return $this->i2osp($temp, $this->k);
}
/**
* Encryption
*
* Both self::PADDING_OAEP and self::PADDING_PKCS1 both place limits on how long $plaintext can be.
* If $plaintext exceeds those limits it will be broken up so that it does and the resultant ciphertext's will
* be concatenated together.
*
* @see self::decrypt()
* @param string $plaintext
* @return bool|string
* @throws \LengthException if the RSA modulus is too short
*/
public function encrypt($plaintext)
{
switch ($this->encryptionPadding) {
case self::ENCRYPTION_NONE:
return $this->raw_encrypt($plaintext);
case self::ENCRYPTION_PKCS1:
return $this->rsaes_pkcs1_v1_5_encrypt($plaintext);
//case self::ENCRYPTION_OAEP:
default:
return $this->rsaes_oaep_encrypt($plaintext);
}
}
/**
* Returns the public key
*
* The public key is only returned under two circumstances - if the private key had the public key embedded within it
* or if the public key was set via setPublicKey(). If the currently loaded key is supposed to be the public key this
* function won't return it since this library, for the most part, doesn't distinguish between public and private keys.
*
* @param string $type
* @param array $options optional
* @return mixed
*/
public function toString($type, array $options = [])
{
$type = self::validatePlugin('Keys', $type, 'savePublicKey');
if ($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');
}
}
return $type::savePublicKey($this->modulus, $this->publicExponent, $options);
}
/**
* Converts a public key to a private key
*
* @return RSA
*/
public function asPrivateKey()
{
$new = new PrivateKey();
$new->exponent = $this->exponent;
$new->modulus = $this->modulus;
$new->k = $this->k;
$new->format = $this->format;
return $new
->withHash($this->hash->getHash())
->withMGFHash($this->mgfHash->getHash())
->withSaltLength($this->sLen)
->withLabel($this->label)
->withPadding($this->signaturePadding | $this->encryptionPadding);
}
}
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