1<?php
2
3/**
4 * RSA Private Key
5 *
6 * @author    Jim Wigginton <terrafrost@php.net>
7 * @copyright 2015 Jim Wigginton
8 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
9 * @link      http://phpseclib.sourceforge.net
10 */
11
12namespace phpseclib3\Crypt\RSA;
13
14use phpseclib3\Crypt\Common;
15use phpseclib3\Crypt\Random;
16use phpseclib3\Crypt\RSA;
17use phpseclib3\Crypt\RSA\Formats\Keys\PSS;
18use phpseclib3\Exception\UnsupportedFormatException;
19use phpseclib3\Math\BigInteger;
20
21/**
22 * Raw RSA Key Handler
23 *
24 * @author  Jim Wigginton <terrafrost@php.net>
25 */
26final class PrivateKey extends RSA implements Common\PrivateKey
27{
28    use Common\Traits\PasswordProtected;
29
30    /**
31     * Primes for Chinese Remainder Theorem (ie. p and q)
32     *
33     * @var array
34     */
35    protected $primes;
36
37    /**
38     * Exponents for Chinese Remainder Theorem (ie. dP and dQ)
39     *
40     * @var array
41     */
42    protected $exponents;
43
44    /**
45     * Coefficients for Chinese Remainder Theorem (ie. qInv)
46     *
47     * @var array
48     */
49    protected $coefficients;
50
51    /**
52     * Private Exponent
53     *
54     * @var \phpseclib3\Math\BigInteger
55     */
56    protected $privateExponent;
57
58    /**
59     * RSADP
60     *
61     * See {@link http://tools.ietf.org/html/rfc3447#section-5.1.2 RFC3447#section-5.1.2}.
62     *
63     * @return bool|\phpseclib3\Math\BigInteger
64     */
65    private function rsadp(BigInteger $c)
66    {
67        if ($c->compare(self::$zero) < 0 || $c->compare($this->modulus) > 0) {
68            throw new \OutOfRangeException('Ciphertext representative out of range');
69        }
70        return $this->exponentiate($c);
71    }
72
73    /**
74     * RSASP1
75     *
76     * See {@link http://tools.ietf.org/html/rfc3447#section-5.2.1 RFC3447#section-5.2.1}.
77     *
78     * @return bool|\phpseclib3\Math\BigInteger
79     */
80    private function rsasp1(BigInteger $m)
81    {
82        if ($m->compare(self::$zero) < 0 || $m->compare($this->modulus) > 0) {
83            throw new \OutOfRangeException('Signature representative out of range');
84        }
85        return $this->exponentiate($m);
86    }
87
88    /**
89     * Exponentiate
90     *
91     * @param \phpseclib3\Math\BigInteger $x
92     * @return \phpseclib3\Math\BigInteger
93     */
94    protected function exponentiate(BigInteger $x)
95    {
96        switch (true) {
97            case empty($this->primes):
98            case $this->primes[1]->equals(self::$zero):
99            case empty($this->coefficients):
100            case $this->coefficients[2]->equals(self::$zero):
101            case empty($this->exponents):
102            case $this->exponents[1]->equals(self::$zero):
103                return $x->modPow($this->exponent, $this->modulus);
104        }
105
106        $num_primes = count($this->primes);
107
108        if (!static::$enableBlinding) {
109            $m_i = [
110                1 => $x->modPow($this->exponents[1], $this->primes[1]),
111                2 => $x->modPow($this->exponents[2], $this->primes[2])
112            ];
113            $h = $m_i[1]->subtract($m_i[2]);
114            $h = $h->multiply($this->coefficients[2]);
115            list(, $h) = $h->divide($this->primes[1]);
116            $m = $m_i[2]->add($h->multiply($this->primes[2]));
117
118            $r = $this->primes[1];
119            for ($i = 3; $i <= $num_primes; $i++) {
120                $m_i = $x->modPow($this->exponents[$i], $this->primes[$i]);
121
122                $r = $r->multiply($this->primes[$i - 1]);
123
124                $h = $m_i->subtract($m);
125                $h = $h->multiply($this->coefficients[$i]);
126                list(, $h) = $h->divide($this->primes[$i]);
127
128                $m = $m->add($r->multiply($h));
129            }
130        } else {
131            $smallest = $this->primes[1];
132            for ($i = 2; $i <= $num_primes; $i++) {
133                if ($smallest->compare($this->primes[$i]) > 0) {
134                    $smallest = $this->primes[$i];
135                }
136            }
137
138            $r = BigInteger::randomRange(self::$one, $smallest->subtract(self::$one));
139
140            $m_i = [
141                1 => $this->blind($x, $r, 1),
142                2 => $this->blind($x, $r, 2)
143            ];
144            $h = $m_i[1]->subtract($m_i[2]);
145            $h = $h->multiply($this->coefficients[2]);
146            list(, $h) = $h->divide($this->primes[1]);
147            $m = $m_i[2]->add($h->multiply($this->primes[2]));
148
149            $r = $this->primes[1];
150            for ($i = 3; $i <= $num_primes; $i++) {
151                $m_i = $this->blind($x, $r, $i);
152
153                $r = $r->multiply($this->primes[$i - 1]);
154
155                $h = $m_i->subtract($m);
156                $h = $h->multiply($this->coefficients[$i]);
157                list(, $h) = $h->divide($this->primes[$i]);
158
159                $m = $m->add($r->multiply($h));
160            }
161        }
162
163        return $m;
164    }
165
166    /**
167     * Performs RSA Blinding
168     *
169     * Protects against timing attacks by employing RSA Blinding.
170     * Returns $x->modPow($this->exponents[$i], $this->primes[$i])
171     *
172     * @param \phpseclib3\Math\BigInteger $x
173     * @param \phpseclib3\Math\BigInteger $r
174     * @param int $i
175     * @return \phpseclib3\Math\BigInteger
176     */
177    private function blind(BigInteger $x, BigInteger $r, $i)
178    {
179        $x = $x->multiply($r->modPow($this->publicExponent, $this->primes[$i]));
180        $x = $x->modPow($this->exponents[$i], $this->primes[$i]);
181
182        $r = $r->modInverse($this->primes[$i]);
183        $x = $x->multiply($r);
184        list(, $x) = $x->divide($this->primes[$i]);
185
186        return $x;
187    }
188
189    /**
190     * EMSA-PSS-ENCODE
191     *
192     * See {@link http://tools.ietf.org/html/rfc3447#section-9.1.1 RFC3447#section-9.1.1}.
193     *
194     * @return string
195     * @param string $m
196     * @throws \RuntimeException on encoding error
197     * @param int $emBits
198     */
199    private function emsa_pss_encode($m, $emBits)
200    {
201        // if $m is larger than two million terrabytes and you're using sha1, PKCS#1 suggests a "Label too long" error
202        // be output.
203
204        $emLen = ($emBits + 1) >> 3; // ie. ceil($emBits / 8)
205        $sLen = $this->sLen !== null ? $this->sLen : $this->hLen;
206
207        $mHash = $this->hash->hash($m);
208        if ($emLen < $this->hLen + $sLen + 2) {
209            throw new \LengthException('RSA modulus too short');
210        }
211
212        $salt = Random::string($sLen);
213        $m2 = "\0\0\0\0\0\0\0\0" . $mHash . $salt;
214        $h = $this->hash->hash($m2);
215        $ps = str_repeat(chr(0), $emLen - $sLen - $this->hLen - 2);
216        $db = $ps . chr(1) . $salt;
217        $dbMask = $this->mgf1($h, $emLen - $this->hLen - 1); // ie. stlren($db)
218        $maskedDB = $db ^ $dbMask;
219        $maskedDB[0] = ~chr(0xFF << ($emBits & 7)) & $maskedDB[0];
220        $em = $maskedDB . $h . chr(0xBC);
221
222        return $em;
223    }
224
225    /**
226     * RSASSA-PSS-SIGN
227     *
228     * See {@link http://tools.ietf.org/html/rfc3447#section-8.1.1 RFC3447#section-8.1.1}.
229     *
230     * @param string $m
231     * @return bool|string
232     */
233    private function rsassa_pss_sign($m)
234    {
235        // EMSA-PSS encoding
236
237        $em = $this->emsa_pss_encode($m, 8 * $this->k - 1);
238
239        // RSA signature
240
241        $m = $this->os2ip($em);
242        $s = $this->rsasp1($m);
243        $s = $this->i2osp($s, $this->k);
244
245        // Output the signature S
246
247        return $s;
248    }
249
250    /**
251     * RSASSA-PKCS1-V1_5-SIGN
252     *
253     * See {@link http://tools.ietf.org/html/rfc3447#section-8.2.1 RFC3447#section-8.2.1}.
254     *
255     * @param string $m
256     * @throws \LengthException if the RSA modulus is too short
257     * @return bool|string
258     */
259    private function rsassa_pkcs1_v1_5_sign($m)
260    {
261        // EMSA-PKCS1-v1_5 encoding
262
263        // If the encoding operation outputs "intended encoded message length too short," output "RSA modulus
264        // too short" and stop.
265        try {
266            $em = $this->emsa_pkcs1_v1_5_encode($m, $this->k);
267        } catch (\LengthException $e) {
268            throw new \LengthException('RSA modulus too short');
269        }
270
271        // RSA signature
272
273        $m = $this->os2ip($em);
274        $s = $this->rsasp1($m);
275        $s = $this->i2osp($s, $this->k);
276
277        // Output the signature S
278
279        return $s;
280    }
281
282    /**
283     * Create a signature
284     *
285     * @see self::verify()
286     * @param string $message
287     * @return string
288     */
289    public function sign($message)
290    {
291        switch ($this->signaturePadding) {
292            case self::SIGNATURE_PKCS1:
293            case self::SIGNATURE_RELAXED_PKCS1:
294                return $this->rsassa_pkcs1_v1_5_sign($message);
295            //case self::SIGNATURE_PSS:
296            default:
297                return $this->rsassa_pss_sign($message);
298        }
299    }
300
301    /**
302     * RSAES-PKCS1-V1_5-DECRYPT
303     *
304     * See {@link http://tools.ietf.org/html/rfc3447#section-7.2.2 RFC3447#section-7.2.2}.
305     *
306     * @param string $c
307     * @return bool|string
308     */
309    private function rsaes_pkcs1_v1_5_decrypt($c)
310    {
311        // Length checking
312
313        if (strlen($c) != $this->k) { // or if k < 11
314            throw new \LengthException('Ciphertext representative too long');
315        }
316
317        // RSA decryption
318
319        $c = $this->os2ip($c);
320        $m = $this->rsadp($c);
321        $em = $this->i2osp($m, $this->k);
322
323        // EME-PKCS1-v1_5 decoding
324
325        if (ord($em[0]) != 0 || ord($em[1]) > 2) {
326            throw new \RuntimeException('Decryption error');
327        }
328
329        $ps = substr($em, 2, strpos($em, chr(0), 2) - 2);
330        $m = substr($em, strlen($ps) + 3);
331
332        if (strlen($ps) < 8) {
333            throw new \RuntimeException('Decryption error');
334        }
335
336        // Output M
337
338        return $m;
339    }
340
341    /**
342     * RSAES-OAEP-DECRYPT
343     *
344     * See {@link http://tools.ietf.org/html/rfc3447#section-7.1.2 RFC3447#section-7.1.2}.  The fact that the error
345     * messages aren't distinguishable from one another hinders debugging, but, to quote from RFC3447#section-7.1.2:
346     *
347     *    Note.  Care must be taken to ensure that an opponent cannot
348     *    distinguish the different error conditions in Step 3.g, whether by
349     *    error message or timing, or, more generally, learn partial
350     *    information about the encoded message EM.  Otherwise an opponent may
351     *    be able to obtain useful information about the decryption of the
352     *    ciphertext C, leading to a chosen-ciphertext attack such as the one
353     *    observed by Manger [36].
354     *
355     * @param string $c
356     * @return bool|string
357     */
358    private function rsaes_oaep_decrypt($c)
359    {
360        // Length checking
361
362        // if $l is larger than two million terrabytes and you're using sha1, PKCS#1 suggests a "Label too long" error
363        // be output.
364
365        if (strlen($c) != $this->k || $this->k < 2 * $this->hLen + 2) {
366            throw new \LengthException('Ciphertext representative too long');
367        }
368
369        // RSA decryption
370
371        $c = $this->os2ip($c);
372        $m = $this->rsadp($c);
373        $em = $this->i2osp($m, $this->k);
374
375        // EME-OAEP decoding
376
377        $lHash = $this->hash->hash($this->label);
378        $y = ord($em[0]);
379        $maskedSeed = substr($em, 1, $this->hLen);
380        $maskedDB = substr($em, $this->hLen + 1);
381        $seedMask = $this->mgf1($maskedDB, $this->hLen);
382        $seed = $maskedSeed ^ $seedMask;
383        $dbMask = $this->mgf1($seed, $this->k - $this->hLen - 1);
384        $db = $maskedDB ^ $dbMask;
385        $lHash2 = substr($db, 0, $this->hLen);
386        $m = substr($db, $this->hLen);
387        $hashesMatch = hash_equals($lHash, $lHash2);
388        $leadingZeros = 1;
389        $patternMatch = 0;
390        $offset = 0;
391        for ($i = 0; $i < strlen($m); $i++) {
392            $patternMatch |= $leadingZeros & ($m[$i] === "\1");
393            $leadingZeros &= $m[$i] === "\0";
394            $offset += $patternMatch ? 0 : 1;
395        }
396
397        // we do | instead of || to avoid https://en.wikipedia.org/wiki/Short-circuit_evaluation
398        // to protect against timing attacks
399        if (!$hashesMatch | !$patternMatch) {
400            throw new \RuntimeException('Decryption error');
401        }
402
403        // Output the message M
404
405        return substr($m, $offset + 1);
406    }
407
408    /**
409     * Raw Encryption / Decryption
410     *
411     * Doesn't use padding and is not recommended.
412     *
413     * @param string $m
414     * @return bool|string
415     * @throws \LengthException if strlen($m) > $this->k
416     */
417    private function raw_encrypt($m)
418    {
419        if (strlen($m) > $this->k) {
420            throw new \LengthException('Ciphertext representative too long');
421        }
422
423        $temp = $this->os2ip($m);
424        $temp = $this->rsadp($temp);
425        return  $this->i2osp($temp, $this->k);
426    }
427
428    /**
429     * Decryption
430     *
431     * @see self::encrypt()
432     * @param string $ciphertext
433     * @return bool|string
434     */
435    public function decrypt($ciphertext)
436    {
437        switch ($this->encryptionPadding) {
438            case self::ENCRYPTION_NONE:
439                return $this->raw_encrypt($ciphertext);
440            case self::ENCRYPTION_PKCS1:
441                return $this->rsaes_pkcs1_v1_5_decrypt($ciphertext);
442            //case self::ENCRYPTION_OAEP:
443            default:
444                return $this->rsaes_oaep_decrypt($ciphertext);
445        }
446    }
447
448    /**
449     * Returns the public key
450     *
451     * @return mixed
452     */
453    public function getPublicKey()
454    {
455        $type = self::validatePlugin('Keys', 'PKCS8', 'savePublicKey');
456        if (empty($this->modulus) || empty($this->publicExponent)) {
457            throw new \RuntimeException('Public key components not found');
458        }
459
460        $key = $type::savePublicKey($this->modulus, $this->publicExponent);
461        return RSA::loadFormat('PKCS8', $key)
462            ->withHash($this->hash->getHash())
463            ->withMGFHash($this->mgfHash->getHash())
464            ->withSaltLength($this->sLen)
465            ->withLabel($this->label)
466            ->withPadding($this->signaturePadding | $this->encryptionPadding);
467    }
468
469    /**
470     * Returns the private key
471     *
472     * @param string $type
473     * @param array $options optional
474     * @return string
475     */
476    public function toString($type, array $options = [])
477    {
478        $type = self::validatePlugin(
479            'Keys',
480            $type,
481            empty($this->primes) ? 'savePublicKey' : 'savePrivateKey'
482        );
483
484        if ($type == PSS::class) {
485            if ($this->signaturePadding == self::SIGNATURE_PSS) {
486                $options += [
487                    'hash' => $this->hash->getHash(),
488                    'MGFHash' => $this->mgfHash->getHash(),
489                    'saltLength' => $this->getSaltLength()
490                ];
491            } else {
492                throw new UnsupportedFormatException('The PSS format can only be used when the signature method has been explicitly set to PSS');
493            }
494        }
495
496        if (empty($this->primes)) {
497            return $type::savePublicKey($this->modulus, $this->exponent, $options);
498        }
499
500        return $type::savePrivateKey($this->modulus, $this->publicExponent, $this->exponent, $this->primes, $this->exponents, $this->coefficients, $this->password, $options);
501
502        /*
503        $key = $type::savePrivateKey($this->modulus, $this->publicExponent, $this->exponent, $this->primes, $this->exponents, $this->coefficients, $this->password, $options);
504        if ($key !== false || count($this->primes) == 2) {
505            return $key;
506        }
507
508        $nSize = $this->getSize() >> 1;
509
510        $primes = [1 => clone self::$one, clone self::$one];
511        $i = 1;
512        foreach ($this->primes as $prime) {
513            $primes[$i] = $primes[$i]->multiply($prime);
514            if ($primes[$i]->getLength() >= $nSize) {
515                $i++;
516            }
517        }
518
519        $exponents = [];
520        $coefficients = [2 => $primes[2]->modInverse($primes[1])];
521
522        foreach ($primes as $i => $prime) {
523            $temp = $prime->subtract(self::$one);
524            $exponents[$i] = $this->modulus->modInverse($temp);
525        }
526
527        return $type::savePrivateKey($this->modulus, $this->publicExponent, $this->exponent, $primes, $exponents, $coefficients, $this->password, $options);
528        */
529    }
530}
531