1/*
2 * Copyright (c) 2006 - 2007, 2010 Kungliga Tekniska Högskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <config.h>
35
36#include <stdio.h>
37#include <stdlib.h>
38#include <krb5-types.h>
39#include <assert.h>
40
41#include <rsa.h>
42
43#include <roken.h>
44
45#ifdef USE_HCRYPTO_TFM
46
47#include "tfm.h"
48
49static void
50BN2mpz(fp_int *s, const BIGNUM *bn)
51{
52    size_t len;
53    void *p;
54
55    fp_init(s);
56
57    len = BN_num_bytes(bn);
58    p = malloc(len);
59    BN_bn2bin(bn, p);
60    fp_read_unsigned_bin(s, p, len);
61    free(p);
62}
63
64static int
65tfm_rsa_private_calculate(fp_int * in, fp_int * p,  fp_int * q,
66			  fp_int * dmp1, fp_int * dmq1, fp_int * iqmp,
67			  fp_int * out)
68{
69    fp_int vp, vq, u;
70
71    fp_init_multi(&vp, &vq, &u, NULL);
72
73    /* vq = c ^ (d mod (q - 1)) mod q */
74    /* vp = c ^ (d mod (p - 1)) mod p */
75    fp_mod(in, p, &u);
76    fp_exptmod(&u, dmp1, p, &vp);
77    fp_mod(in, q, &u);
78    fp_exptmod(&u, dmq1, q, &vq);
79
80    /* C2 = 1/q mod p  (iqmp) */
81    /* u = (vp - vq)C2 mod p. */
82    fp_sub(&vp, &vq, &u);
83    if (fp_isneg(&u))
84	fp_add(&u, p, &u);
85    fp_mul(&u, iqmp, &u);
86    fp_mod(&u, p, &u);
87
88    /* c ^ d mod n = vq + u q */
89    fp_mul(&u, q, &u);
90    fp_add(&u, &vq, out);
91
92    fp_zero_multi(&vp, &vq, &u, NULL);
93
94    return 0;
95}
96
97/*
98 *
99 */
100
101static int
102tfm_rsa_public_encrypt(int flen, const unsigned char* from,
103			unsigned char* to, RSA* rsa, int padding)
104{
105    unsigned char *p, *p0;
106    int res;
107    size_t size, padlen;
108    fp_int enc, dec, n, e;
109
110    if (padding != RSA_PKCS1_PADDING)
111	return -1;
112
113    size = RSA_size(rsa);
114
115    if (size < RSA_PKCS1_PADDING_SIZE || size - RSA_PKCS1_PADDING_SIZE < flen)
116	return -2;
117
118    BN2mpz(&n, rsa->n);
119    BN2mpz(&e, rsa->e);
120
121    p = p0 = malloc(size - 1);
122    if (p0 == NULL) {
123	fp_zero_multi(&e, &n, NULL);
124	return -3;
125    }
126
127    padlen = size - flen - 3;
128
129    *p++ = 2;
130    if (RAND_bytes(p, padlen) != 1) {
131	fp_zero_multi(&e, &n, NULL);
132	free(p0);
133	return -4;
134    }
135    while(padlen) {
136	if (*p == 0)
137	    *p = 1;
138	padlen--;
139	p++;
140    }
141    *p++ = 0;
142    memcpy(p, from, flen);
143    p += flen;
144    assert((p - p0) == size - 1);
145
146    fp_init_multi(&enc, &dec, NULL);
147    fp_read_unsigned_bin(&dec, p0, size - 1);
148    free(p0);
149
150    res = fp_exptmod(&dec, &e, &n, &enc);
151
152    fp_zero_multi(&dec, &e, &n, NULL);
153
154    if (res != 0)
155	return -4;
156
157    {
158	size_t ssize;
159	ssize = fp_unsigned_bin_size(&enc);
160	assert(size >= ssize);
161	fp_to_unsigned_bin(&enc, to);
162	size = ssize;
163    }
164    fp_zero(&enc);
165
166    return size;
167}
168
169static int
170tfm_rsa_public_decrypt(int flen, const unsigned char* from,
171		       unsigned char* to, RSA* rsa, int padding)
172{
173    unsigned char *p;
174    int res;
175    size_t size;
176    fp_int s, us, n, e;
177
178    if (padding != RSA_PKCS1_PADDING)
179	return -1;
180
181    if (flen > RSA_size(rsa))
182	return -2;
183
184    BN2mpz(&n, rsa->n);
185    BN2mpz(&e, rsa->e);
186
187#if 0
188    /* Check that the exponent is larger then 3 */
189    if (mp_int_compare_value(&e, 3) <= 0) {
190	fp_zero_multi(&e, &n, NULL);
191	return -3;
192    }
193#endif
194
195    fp_init_multi(&s, &us, NULL);
196    fp_read_unsigned_bin(&s, rk_UNCONST(from), flen);
197
198    if (fp_cmp(&s, &n) >= 0) {
199	fp_zero_multi(&e, &n, NULL);
200	return -4;
201    }
202
203    res = fp_exptmod(&s, &e, &n, &us);
204
205    fp_zero_multi(&s, &e, &n, NULL);
206
207    if (res != 0)
208	return -5;
209    p = to;
210
211
212    size = fp_unsigned_bin_size(&us);
213    assert(size <= RSA_size(rsa));
214    fp_to_unsigned_bin(&us, p);
215
216    fp_zero(&us);
217
218    /* head zero was skipped by fp_to_unsigned_bin */
219    if (*p == 0)
220	return -6;
221    if (*p != 1)
222	return -7;
223    size--; p++;
224    while (size && *p == 0xff) {
225	size--; p++;
226    }
227    if (size == 0 || *p != 0)
228	return -8;
229    size--; p++;
230
231    memmove(to, p, size);
232
233    return size;
234}
235
236static int
237tfm_rsa_private_encrypt(int flen, const unsigned char* from,
238			unsigned char* to, RSA* rsa, int padding)
239{
240    unsigned char *p, *p0;
241    int res;
242    int size;
243    fp_int in, out, n, e;
244
245    if (padding != RSA_PKCS1_PADDING)
246	return -1;
247
248    size = RSA_size(rsa);
249
250    if (size < RSA_PKCS1_PADDING_SIZE || size - RSA_PKCS1_PADDING_SIZE < flen)
251	return -2;
252
253    p0 = p = malloc(size);
254    *p++ = 0;
255    *p++ = 1;
256    memset(p, 0xff, size - flen - 3);
257    p += size - flen - 3;
258    *p++ = 0;
259    memcpy(p, from, flen);
260    p += flen;
261    assert((p - p0) == size);
262
263    BN2mpz(&n, rsa->n);
264    BN2mpz(&e, rsa->e);
265
266    fp_init_multi(&in, &out, NULL);
267    fp_read_unsigned_bin(&in, p0, size);
268    free(p0);
269
270    if(fp_isneg(&in) || fp_cmp(&in, &n) >= 0) {
271	size = -3;
272	goto out;
273    }
274
275    if (rsa->p && rsa->q && rsa->dmp1 && rsa->dmq1 && rsa->iqmp) {
276	fp_int p, q, dmp1, dmq1, iqmp;
277
278	BN2mpz(&p, rsa->p);
279	BN2mpz(&q, rsa->q);
280	BN2mpz(&dmp1, rsa->dmp1);
281	BN2mpz(&dmq1, rsa->dmq1);
282	BN2mpz(&iqmp, rsa->iqmp);
283
284	res = tfm_rsa_private_calculate(&in, &p, &q, &dmp1, &dmq1, &iqmp, &out);
285
286	fp_zero_multi(&p, &q, &dmp1, &dmq1, &iqmp, NULL);
287
288	if (res != 0) {
289	    size = -4;
290	    goto out;
291	}
292    } else {
293	fp_int d;
294
295	BN2mpz(&d, rsa->d);
296	res = fp_exptmod(&in, &d, &n, &out);
297	fp_zero(&d);
298	if (res != 0) {
299	    size = -5;
300	    goto out;
301	}
302    }
303
304    if (size > 0) {
305	size_t ssize;
306	ssize = fp_unsigned_bin_size(&out);
307	assert(size >= ssize);
308	fp_to_unsigned_bin(&out, to);
309	size = ssize;
310    }
311
312 out:
313    fp_zero_multi(&e, &n, &in, &out, NULL);
314
315    return size;
316}
317
318static int
319tfm_rsa_private_decrypt(int flen, const unsigned char* from,
320			unsigned char* to, RSA* rsa, int padding)
321{
322    unsigned char *ptr;
323    int res;
324    int size;
325    fp_int in, out, n, e;
326
327    if (padding != RSA_PKCS1_PADDING)
328	return -1;
329
330    size = RSA_size(rsa);
331    if (flen > size)
332	return -2;
333
334    fp_init_multi(&in, &out, NULL);
335
336    BN2mpz(&n, rsa->n);
337    BN2mpz(&e, rsa->e);
338
339    fp_read_unsigned_bin(&in, rk_UNCONST(from), flen);
340
341    if(fp_isneg(&in) || fp_cmp(&in, &n) >= 0) {
342	size = -2;
343	goto out;
344    }
345
346    if (rsa->p && rsa->q && rsa->dmp1 && rsa->dmq1 && rsa->iqmp) {
347	fp_int p, q, dmp1, dmq1, iqmp;
348
349	BN2mpz(&p, rsa->p);
350	BN2mpz(&q, rsa->q);
351	BN2mpz(&dmp1, rsa->dmp1);
352	BN2mpz(&dmq1, rsa->dmq1);
353	BN2mpz(&iqmp, rsa->iqmp);
354
355	res = tfm_rsa_private_calculate(&in, &p, &q, &dmp1, &dmq1, &iqmp, &out);
356
357	fp_zero_multi(&p, &q, &dmp1, &dmq1, &iqmp, NULL);
358
359	if (res != 0) {
360	    size = -3;
361	    goto out;
362	}
363
364    } else {
365	fp_int d;
366
367	if(fp_isneg(&in) || fp_cmp(&in, &n) >= 0)
368	    return -4;
369
370	BN2mpz(&d, rsa->d);
371	res = fp_exptmod(&in, &d, &n, &out);
372	fp_zero(&d);
373	if (res != 0) {
374	    size = -5;
375	    goto out;
376	}
377    }
378
379    ptr = to;
380    {
381	size_t ssize;
382	ssize = fp_unsigned_bin_size(&out);
383	assert(size >= ssize);
384	fp_to_unsigned_bin(&out, ptr);
385	size = ssize;
386    }
387
388    /* head zero was skipped by mp_int_to_unsigned */
389    if (*ptr != 2) {
390	size = -6;
391	goto out;
392    }
393    size--; ptr++;
394    while (size && *ptr != 0) {
395	size--; ptr++;
396    }
397    if (size == 0)
398	return -7;
399    size--; ptr++;
400
401    memmove(to, ptr, size);
402
403 out:
404    fp_zero_multi(&e, &n, &in, &out, NULL);
405
406    return size;
407}
408
409static BIGNUM *
410mpz2BN(fp_int *s)
411{
412    size_t size;
413    BIGNUM *bn;
414    void *p;
415
416    size = fp_unsigned_bin_size(s);
417    p = malloc(size);
418    if (p == NULL && size != 0)
419	return NULL;
420
421    fp_to_unsigned_bin(s, p);
422
423    bn = BN_bin2bn(p, size, NULL);
424    free(p);
425    return bn;
426}
427
428static int
429random_num(fp_int *num, size_t len)
430{
431    unsigned char *p;
432
433    len = (len + 7) / 8;
434    p = malloc(len);
435    if (p == NULL)
436	return 1;
437    if (RAND_bytes(p, len) != 1) {
438	free(p);
439	return 1;
440    }
441    fp_read_unsigned_bin(num, p, len);
442    free(p);
443    return 0;
444}
445
446#define CHECK(f, v) if ((f) != (v)) { goto out; }
447
448static int
449tfm_rsa_generate_key(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb)
450{
451    fp_int el, p, q, n, d, dmp1, dmq1, iqmp, t1, t2, t3;
452    int counter, ret, bitsp;
453
454    if (bits < 789)
455	return -1;
456
457    bitsp = (bits + 1) / 2;
458
459    ret = -1;
460
461    fp_init_multi(&el, &p, &q, &n, &n, &d, &dmp1, &dmq1, &iqmp, &t1, &t2, &t3, NULL);
462
463    BN2mpz(&el, e);
464
465    /* generate p and q so that p != q and bits(pq) ~ bits */
466    counter = 0;
467    do {
468	BN_GENCB_call(cb, 2, counter++);
469	CHECK(random_num(&p, bitsp), 0);
470	CHECK(fp_find_prime(&p), FP_YES);
471
472	fp_sub_d(&p, 1, &t1);
473	fp_gcd(&t1, &el, &t2);
474    } while(fp_cmp_d(&t2, 1) != 0);
475
476    BN_GENCB_call(cb, 3, 0);
477
478    counter = 0;
479    do {
480	BN_GENCB_call(cb, 2, counter++);
481	CHECK(random_num(&q, bits - bitsp), 0);
482	CHECK(fp_find_prime(&q), FP_YES);
483
484	if (fp_cmp(&p, &q) == 0) /* don't let p and q be the same */
485	    continue;
486
487	fp_sub_d(&q, 1, &t1);
488	fp_gcd(&t1, &el, &t2);
489    } while(fp_cmp_d(&t2, 1) != 0);
490
491    /* make p > q */
492    if (fp_cmp(&p, &q) < 0) {
493	fp_int c;
494	fp_copy(&p, &c);
495	fp_copy(&q, &p);
496	fp_copy(&c, &q);
497    }
498
499    BN_GENCB_call(cb, 3, 1);
500
501    /* calculate n,  		n = p * q */
502    fp_mul(&p, &q, &n);
503
504    /* calculate d, 		d = 1/e mod (p - 1)(q - 1) */
505    fp_sub_d(&p, 1, &t1);
506    fp_sub_d(&q, 1, &t2);
507    fp_mul(&t1, &t2, &t3);
508    fp_invmod(&el, &t3, &d);
509
510    /* calculate dmp1		dmp1 = d mod (p-1) */
511    fp_mod(&d, &t1, &dmp1);
512    /* calculate dmq1		dmq1 = d mod (q-1) */
513    fp_mod(&d, &t2, &dmq1);
514    /* calculate iqmp 		iqmp = 1/q mod p */
515    fp_invmod(&q, &p, &iqmp);
516
517    /* fill in RSA key */
518
519    rsa->e = mpz2BN(&el);
520    rsa->p = mpz2BN(&p);
521    rsa->q = mpz2BN(&q);
522    rsa->n = mpz2BN(&n);
523    rsa->d = mpz2BN(&d);
524    rsa->dmp1 = mpz2BN(&dmp1);
525    rsa->dmq1 = mpz2BN(&dmq1);
526    rsa->iqmp = mpz2BN(&iqmp);
527
528    ret = 1;
529
530out:
531    fp_zero_multi(&el, &p, &q, &n, &d, &dmp1,
532		  &dmq1, &iqmp, &t1, &t2, &t3, NULL);
533
534    return ret;
535}
536
537static int
538tfm_rsa_init(RSA *rsa)
539{
540    return 1;
541}
542
543static int
544tfm_rsa_finish(RSA *rsa)
545{
546    return 1;
547}
548
549const RSA_METHOD hc_rsa_tfm_method = {
550    "hcrypto tfm RSA",
551    tfm_rsa_public_encrypt,
552    tfm_rsa_public_decrypt,
553    tfm_rsa_private_encrypt,
554    tfm_rsa_private_decrypt,
555    NULL,
556    NULL,
557    tfm_rsa_init,
558    tfm_rsa_finish,
559    0,
560    NULL,
561    NULL,
562    NULL,
563    tfm_rsa_generate_key
564};
565
566#endif
567
568const RSA_METHOD *
569RSA_tfm_method(void)
570{
571#ifdef USE_HCRYPTO_TFM
572    return &hc_rsa_tfm_method;
573#else
574    return NULL;
575#endif
576}
577
578#endif
579