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Damien Millercee85232009-03-06 00:58:22 +11001/* $OpenBSD: schnorr.c,v 1.3 2009/03/05 07:18:19 djm Exp $ */
Damien Miller01ed2272008-11-05 16:20:46 +11002/*
3 * Copyright (c) 2008 Damien Miller. All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/*
19 * Implementation of Schnorr signatures / zero-knowledge proofs, based on
20 * description in:
21 *
22 * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling",
23 * 16th Workshop on Security Protocols, Cambridge, April 2008
24 *
25 * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
26 */
27
28#include "includes.h"
29
30#include <sys/types.h>
31
32#include <string.h>
33#include <stdarg.h>
34#include <stdio.h>
35
36#include <openssl/evp.h>
37#include <openssl/bn.h>
38
39#include "xmalloc.h"
40#include "buffer.h"
41#include "log.h"
42
Damien Millercee85232009-03-06 00:58:22 +110043#include "schnorr.h"
Damien Miller01ed2272008-11-05 16:20:46 +110044
Darren Tucker8aae6ff2009-03-07 12:01:47 +110045#include "openbsd-compat/openssl-compat.h"
46
Damien Miller01ed2272008-11-05 16:20:46 +110047/* #define SCHNORR_DEBUG */ /* Privacy-violating debugging */
48/* #define SCHNORR_MAIN */ /* Include main() selftest */
49
Damien Miller01ed2272008-11-05 16:20:46 +110050#ifndef SCHNORR_DEBUG
51# define SCHNORR_DEBUG_BN(a)
52# define SCHNORR_DEBUG_BUF(a)
53#else
Damien Millercee85232009-03-06 00:58:22 +110054# define SCHNORR_DEBUG_BN(a) debug3_bn a
55# define SCHNORR_DEBUG_BUF(a) debug3_buf a
Damien Miller01ed2272008-11-05 16:20:46 +110056#endif /* SCHNORR_DEBUG */
57
58/*
59 * Calculate hash component of Schnorr signature H(g || g^v || g^x || id)
Damien Millercee85232009-03-06 00:58:22 +110060 * using the hash function defined by "evp_md". Returns signature as
61 * bignum or NULL on error.
Damien Miller01ed2272008-11-05 16:20:46 +110062 */
63static BIGNUM *
64schnorr_hash(const BIGNUM *p, const BIGNUM *q, const BIGNUM *g,
Damien Millercee85232009-03-06 00:58:22 +110065 const EVP_MD *evp_md, const BIGNUM *g_v, const BIGNUM *g_x,
Damien Miller01ed2272008-11-05 16:20:46 +110066 const u_char *id, u_int idlen)
67{
68 u_char *digest;
69 u_int digest_len;
70 BIGNUM *h;
Damien Miller01ed2272008-11-05 16:20:46 +110071 Buffer b;
72 int success = -1;
73
74 if ((h = BN_new()) == NULL) {
75 error("%s: BN_new", __func__);
76 return NULL;
77 }
78
79 buffer_init(&b);
Damien Miller01ed2272008-11-05 16:20:46 +110080
Damien Miller25918382009-02-21 12:45:18 +110081 /* h = H(g || p || q || g^v || g^x || id) */
Damien Miller01ed2272008-11-05 16:20:46 +110082 buffer_put_bignum2(&b, g);
Damien Miller25918382009-02-21 12:45:18 +110083 buffer_put_bignum2(&b, p);
84 buffer_put_bignum2(&b, q);
Damien Miller01ed2272008-11-05 16:20:46 +110085 buffer_put_bignum2(&b, g_v);
86 buffer_put_bignum2(&b, g_x);
87 buffer_put_string(&b, id, idlen);
88
89 SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
90 "%s: hashblob", __func__));
Damien Millercee85232009-03-06 00:58:22 +110091 if (hash_buffer(buffer_ptr(&b), buffer_len(&b), evp_md,
Damien Miller01ed2272008-11-05 16:20:46 +110092 &digest, &digest_len) != 0) {
93 error("%s: hash_buffer", __func__);
94 goto out;
95 }
96 if (BN_bin2bn(digest, (int)digest_len, h) == NULL) {
97 error("%s: BN_bin2bn", __func__);
98 goto out;
99 }
100 success = 0;
101 SCHNORR_DEBUG_BN((h, "%s: h = ", __func__));
102 out:
103 buffer_free(&b);
Damien Miller01ed2272008-11-05 16:20:46 +1100104 bzero(digest, digest_len);
105 xfree(digest);
106 digest_len = 0;
107 if (success == 0)
108 return h;
109 BN_clear_free(h);
110 return NULL;
111}
112
113/*
114 * Generate Schnorr signature to prove knowledge of private value 'x' used
115 * in public exponent g^x, under group defined by 'grp_p', 'grp_q' and 'grp_g'
Damien Millercee85232009-03-06 00:58:22 +1100116 * using the hash function "evp_md".
Damien Miller01ed2272008-11-05 16:20:46 +1100117 * 'idlen' bytes from 'id' will be included in the signature hash as an anti-
118 * replay salt.
Damien Millercee85232009-03-06 00:58:22 +1100119 *
120 * On success, 0 is returned. The signature values are returned as *e_p
121 * (g^v mod p) and *r_p (v - xh mod q). The caller must free these values.
122 * On failure, -1 is returned.
Damien Miller01ed2272008-11-05 16:20:46 +1100123 */
124int
125schnorr_sign(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
Damien Millercee85232009-03-06 00:58:22 +1100126 const EVP_MD *evp_md, const BIGNUM *x, const BIGNUM *g_x,
127 const u_char *id, u_int idlen, BIGNUM **r_p, BIGNUM **e_p)
Damien Miller01ed2272008-11-05 16:20:46 +1100128{
129 int success = -1;
Damien Miller01ed2272008-11-05 16:20:46 +1100130 BIGNUM *h, *tmp, *v, *g_v, *r;
131 BN_CTX *bn_ctx;
132
133 SCHNORR_DEBUG_BN((x, "%s: x = ", __func__));
134 SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__));
135
136 /* Avoid degenerate cases: g^0 yields a spoofable signature */
137 if (BN_cmp(g_x, BN_value_one()) <= 0) {
138 error("%s: g_x < 1", __func__);
139 return -1;
140 }
141
142 h = g_v = r = tmp = v = NULL;
143 if ((bn_ctx = BN_CTX_new()) == NULL) {
144 error("%s: BN_CTX_new", __func__);
145 goto out;
146 }
147 if ((g_v = BN_new()) == NULL ||
148 (r = BN_new()) == NULL ||
149 (tmp = BN_new()) == NULL) {
150 error("%s: BN_new", __func__);
151 goto out;
152 }
153
154 /*
155 * v must be a random element of Zq, so 1 <= v < q
156 * we also exclude v = 1, since g^1 looks dangerous
157 */
158 if ((v = bn_rand_range_gt_one(grp_p)) == NULL) {
159 error("%s: bn_rand_range2", __func__);
160 goto out;
161 }
162 SCHNORR_DEBUG_BN((v, "%s: v = ", __func__));
163
164 /* g_v = g^v mod p */
165 if (BN_mod_exp(g_v, grp_g, v, grp_p, bn_ctx) == -1) {
166 error("%s: BN_mod_exp (g^v mod p)", __func__);
167 goto out;
168 }
169 SCHNORR_DEBUG_BN((g_v, "%s: g_v = ", __func__));
170
171 /* h = H(g || g^v || g^x || id) */
Damien Millercee85232009-03-06 00:58:22 +1100172 if ((h = schnorr_hash(grp_p, grp_q, grp_g, evp_md, g_v, g_x,
Damien Miller01ed2272008-11-05 16:20:46 +1100173 id, idlen)) == NULL) {
174 error("%s: schnorr_hash failed", __func__);
175 goto out;
176 }
177
178 /* r = v - xh mod q */
179 if (BN_mod_mul(tmp, x, h, grp_q, bn_ctx) == -1) {
180 error("%s: BN_mod_mul (tmp = xv mod q)", __func__);
181 goto out;
182 }
183 if (BN_mod_sub(r, v, tmp, grp_q, bn_ctx) == -1) {
184 error("%s: BN_mod_mul (r = v - tmp)", __func__);
185 goto out;
186 }
Damien Millercee85232009-03-06 00:58:22 +1100187 SCHNORR_DEBUG_BN((g_v, "%s: e = ", __func__));
Damien Miller01ed2272008-11-05 16:20:46 +1100188 SCHNORR_DEBUG_BN((r, "%s: r = ", __func__));
189
Damien Millercee85232009-03-06 00:58:22 +1100190 *e_p = g_v;
191 *r_p = r;
192
Damien Miller01ed2272008-11-05 16:20:46 +1100193 success = 0;
194 out:
195 BN_CTX_free(bn_ctx);
196 if (h != NULL)
197 BN_clear_free(h);
198 if (v != NULL)
199 BN_clear_free(v);
Damien Miller01ed2272008-11-05 16:20:46 +1100200 BN_clear_free(tmp);
201
202 return success;
203}
204
205/*
Damien Millercee85232009-03-06 00:58:22 +1100206 * Generate Schnorr signature to prove knowledge of private value 'x' used
207 * in public exponent g^x, under group defined by 'grp_p', 'grp_q' and 'grp_g'
208 * using a SHA256 hash.
209 * 'idlen' bytes from 'id' will be included in the signature hash as an anti-
210 * replay salt.
211 * On success, 0 is returned and *siglen bytes of signature are returned in
212 * *sig (caller to free). Returns -1 on failure.
213 */
214int
215schnorr_sign_buf(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
216 const BIGNUM *x, const BIGNUM *g_x, const u_char *id, u_int idlen,
217 u_char **sig, u_int *siglen)
218{
219 Buffer b;
220 BIGNUM *r, *e;
221
222 if (schnorr_sign(grp_p, grp_q, grp_g, EVP_sha256(),
223 x, g_x, id, idlen, &r, &e) != 0)
224 return -1;
225
226 /* Signature is (e, r) */
227 buffer_init(&b);
228 /* XXX sigtype-hash as string? */
229 buffer_put_bignum2(&b, e);
230 buffer_put_bignum2(&b, r);
231 *siglen = buffer_len(&b);
232 *sig = xmalloc(*siglen);
233 memcpy(*sig, buffer_ptr(&b), *siglen);
234 SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
235 "%s: sigblob", __func__));
236 buffer_free(&b);
237
238 BN_clear_free(r);
239 BN_clear_free(e);
240
241 return 0;
242}
243
244/*
245 * Verify Schnorr signature { r (v - xh mod q), e (g^v mod p) } against
246 * public exponent g_x (g^x) under group defined by 'grp_p', 'grp_q' and
247 * 'grp_g' using hash "evp_md".
Damien Miller01ed2272008-11-05 16:20:46 +1100248 * Signature hash will be salted with 'idlen' bytes from 'id'.
249 * Returns -1 on failure, 0 on incorrect signature or 1 on matching signature.
250 */
251int
252schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
Damien Millercee85232009-03-06 00:58:22 +1100253 const EVP_MD *evp_md, const BIGNUM *g_x, const u_char *id, u_int idlen,
254 const BIGNUM *r, const BIGNUM *e)
Damien Miller01ed2272008-11-05 16:20:46 +1100255{
256 int success = -1;
Damien Millercee85232009-03-06 00:58:22 +1100257 BIGNUM *h, *g_xh, *g_r, *expected;
Damien Miller01ed2272008-11-05 16:20:46 +1100258 BN_CTX *bn_ctx;
Damien Miller01ed2272008-11-05 16:20:46 +1100259
260 SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__));
261
262 /* Avoid degenerate cases: g^0 yields a spoofable signature */
263 if (BN_cmp(g_x, BN_value_one()) <= 0) {
264 error("%s: g_x < 1", __func__);
265 return -1;
266 }
267
Damien Millercee85232009-03-06 00:58:22 +1100268 h = g_xh = g_r = expected = NULL;
Damien Miller01ed2272008-11-05 16:20:46 +1100269 if ((bn_ctx = BN_CTX_new()) == NULL) {
270 error("%s: BN_CTX_new", __func__);
271 goto out;
272 }
Damien Millercee85232009-03-06 00:58:22 +1100273 if ((g_xh = BN_new()) == NULL ||
Damien Miller01ed2272008-11-05 16:20:46 +1100274 (g_r = BN_new()) == NULL ||
275 (expected = BN_new()) == NULL) {
276 error("%s: BN_new", __func__);
277 goto out;
278 }
279
Damien Millercee85232009-03-06 00:58:22 +1100280 SCHNORR_DEBUG_BN((e, "%s: e = ", __func__));
Damien Miller01ed2272008-11-05 16:20:46 +1100281 SCHNORR_DEBUG_BN((r, "%s: r = ", __func__));
282
283 /* h = H(g || g^v || g^x || id) */
Damien Millercee85232009-03-06 00:58:22 +1100284 if ((h = schnorr_hash(grp_p, grp_q, grp_g, evp_md, e, g_x,
Damien Miller01ed2272008-11-05 16:20:46 +1100285 id, idlen)) == NULL) {
286 error("%s: schnorr_hash failed", __func__);
287 goto out;
288 }
289
290 /* g_xh = (g^x)^h */
291 if (BN_mod_exp(g_xh, g_x, h, grp_p, bn_ctx) == -1) {
292 error("%s: BN_mod_exp (g_x^h mod p)", __func__);
293 goto out;
294 }
295 SCHNORR_DEBUG_BN((g_xh, "%s: g_xh = ", __func__));
296
297 /* g_r = g^r */
298 if (BN_mod_exp(g_r, grp_g, r, grp_p, bn_ctx) == -1) {
299 error("%s: BN_mod_exp (g_x^h mod p)", __func__);
300 goto out;
301 }
302 SCHNORR_DEBUG_BN((g_r, "%s: g_r = ", __func__));
303
304 /* expected = g^r * g_xh */
305 if (BN_mod_mul(expected, g_r, g_xh, grp_p, bn_ctx) == -1) {
306 error("%s: BN_mod_mul (expected = g_r mod p)", __func__);
307 goto out;
308 }
309 SCHNORR_DEBUG_BN((expected, "%s: expected = ", __func__));
310
Damien Millercee85232009-03-06 00:58:22 +1100311 /* Check e == expected */
312 success = BN_cmp(expected, e) == 0;
Damien Miller01ed2272008-11-05 16:20:46 +1100313 out:
314 BN_CTX_free(bn_ctx);
315 if (h != NULL)
316 BN_clear_free(h);
Damien Miller01ed2272008-11-05 16:20:46 +1100317 BN_clear_free(g_xh);
318 BN_clear_free(g_r);
319 BN_clear_free(expected);
320 return success;
321}
322
Damien Millercee85232009-03-06 00:58:22 +1100323/*
324 * Verify Schnorr signature 'sig' of length 'siglen' against public exponent
325 * g_x (g^x) under group defined by 'grp_p', 'grp_q' and 'grp_g' using a
326 * SHA256 hash.
327 * Signature hash will be salted with 'idlen' bytes from 'id'.
328 * Returns -1 on failure, 0 on incorrect signature or 1 on matching signature.
329 */
330int
331schnorr_verify_buf(const BIGNUM *grp_p, const BIGNUM *grp_q,
332 const BIGNUM *grp_g,
333 const BIGNUM *g_x, const u_char *id, u_int idlen,
334 const u_char *sig, u_int siglen)
335{
336 Buffer b;
337 int ret = -1;
338 u_int rlen;
339 BIGNUM *r, *e;
340
341 e = r = NULL;
342 if ((e = BN_new()) == NULL ||
343 (r = BN_new()) == NULL) {
344 error("%s: BN_new", __func__);
345 goto out;
346 }
347
348 /* Extract g^v and r from signature blob */
349 buffer_init(&b);
350 buffer_append(&b, sig, siglen);
351 SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
352 "%s: sigblob", __func__));
353 buffer_get_bignum2(&b, e);
354 buffer_get_bignum2(&b, r);
355 rlen = buffer_len(&b);
356 buffer_free(&b);
357 if (rlen != 0) {
358 error("%s: remaining bytes in signature %d", __func__, rlen);
359 goto out;
360 }
361
362 ret = schnorr_verify(grp_p, grp_q, grp_g, EVP_sha256(),
363 g_x, id, idlen, r, e);
364 out:
365 BN_clear_free(e);
366 BN_clear_free(r);
367
368 return ret;
369}
370
371/* Helper functions */
372
373/*
374 * Generate uniformly distributed random number in range (1, high).
375 * Return number on success, NULL on failure.
376 */
377BIGNUM *
378bn_rand_range_gt_one(const BIGNUM *high)
379{
380 BIGNUM *r, *tmp;
381 int success = -1;
382
383 if ((tmp = BN_new()) == NULL) {
384 error("%s: BN_new", __func__);
385 return NULL;
386 }
387 if ((r = BN_new()) == NULL) {
388 error("%s: BN_new failed", __func__);
389 goto out;
390 }
391 if (BN_set_word(tmp, 2) != 1) {
392 error("%s: BN_set_word(tmp, 2)", __func__);
393 goto out;
394 }
395 if (BN_sub(tmp, high, tmp) == -1) {
396 error("%s: BN_sub failed (tmp = high - 2)", __func__);
397 goto out;
398 }
399 if (BN_rand_range(r, tmp) == -1) {
400 error("%s: BN_rand_range failed", __func__);
401 goto out;
402 }
403 if (BN_set_word(tmp, 2) != 1) {
404 error("%s: BN_set_word(tmp, 2)", __func__);
405 goto out;
406 }
407 if (BN_add(r, r, tmp) == -1) {
408 error("%s: BN_add failed (r = r + 2)", __func__);
409 goto out;
410 }
411 success = 0;
412 out:
413 BN_clear_free(tmp);
414 if (success == 0)
415 return r;
416 BN_clear_free(r);
417 return NULL;
418}
419
420/*
421 * Hash contents of buffer 'b' with hash 'md'. Returns 0 on success,
422 * with digest via 'digestp' (caller to free) and length via 'lenp'.
423 * Returns -1 on failure.
424 */
425int
426hash_buffer(const u_char *buf, u_int len, const EVP_MD *md,
427 u_char **digestp, u_int *lenp)
428{
429 u_char digest[EVP_MAX_MD_SIZE];
430 u_int digest_len;
431 EVP_MD_CTX evp_md_ctx;
432 int success = -1;
433
434 EVP_MD_CTX_init(&evp_md_ctx);
435
436 if (EVP_DigestInit_ex(&evp_md_ctx, md, NULL) != 1) {
437 error("%s: EVP_DigestInit_ex", __func__);
438 goto out;
439 }
440 if (EVP_DigestUpdate(&evp_md_ctx, buf, len) != 1) {
441 error("%s: EVP_DigestUpdate", __func__);
442 goto out;
443 }
444 if (EVP_DigestFinal_ex(&evp_md_ctx, digest, &digest_len) != 1) {
445 error("%s: EVP_DigestFinal_ex", __func__);
446 goto out;
447 }
448 *digestp = xmalloc(digest_len);
449 *lenp = digest_len;
450 memcpy(*digestp, digest, *lenp);
451 success = 0;
452 out:
453 EVP_MD_CTX_cleanup(&evp_md_ctx);
454 bzero(digest, sizeof(digest));
455 digest_len = 0;
456 return success;
457}
458
459/* print formatted string followed by bignum */
460void
461debug3_bn(const BIGNUM *n, const char *fmt, ...)
462{
463 char *out, *h;
464 va_list args;
465
466 out = NULL;
467 va_start(args, fmt);
468 vasprintf(&out, fmt, args);
469 va_end(args);
470 if (out == NULL)
471 fatal("%s: vasprintf failed", __func__);
472
473 if (n == NULL)
474 debug3("%s(null)", out);
475 else {
476 h = BN_bn2hex(n);
477 debug3("%s0x%s", out, h);
478 free(h);
479 }
480 free(out);
481}
482
483/* print formatted string followed by buffer contents in hex */
484void
485debug3_buf(const u_char *buf, u_int len, const char *fmt, ...)
486{
487 char *out, h[65];
488 u_int i, j;
489 va_list args;
490
491 out = NULL;
492 va_start(args, fmt);
493 vasprintf(&out, fmt, args);
494 va_end(args);
495 if (out == NULL)
496 fatal("%s: vasprintf failed", __func__);
497
498 debug3("%s length %u%s", out, len, buf == NULL ? " (null)" : "");
499 free(out);
500 if (buf == NULL)
501 return;
502
503 *h = '\0';
504 for (i = j = 0; i < len; i++) {
505 snprintf(h + j, sizeof(h) - j, "%02x", buf[i]);
506 j += 2;
507 if (j >= sizeof(h) - 1 || i == len - 1) {
508 debug3(" %s", h);
509 *h = '\0';
510 j = 0;
511 }
512 }
513}
514
515/*
516 * Construct a MODP group from hex strings p (which must be a safe
517 * prime) and g, automatically calculating subgroup q as (p / 2)
518 */
519struct modp_group *
520modp_group_from_g_and_safe_p(const char *grp_g, const char *grp_p)
521{
522 struct modp_group *ret;
523
524 ret = xmalloc(sizeof(*ret));
525 ret->p = ret->q = ret->g = NULL;
526 if (BN_hex2bn(&ret->p, grp_p) == 0 ||
527 BN_hex2bn(&ret->g, grp_g) == 0)
528 fatal("%s: BN_hex2bn", __func__);
529 /* Subgroup order is p/2 (p is a safe prime) */
530 if ((ret->q = BN_new()) == NULL)
531 fatal("%s: BN_new", __func__);
532 if (BN_rshift1(ret->q, ret->p) != 1)
533 fatal("%s: BN_rshift1", __func__);
534
535 return ret;
536}
537
538void
539modp_group_free(struct modp_group *grp)
540{
541 if (grp->g != NULL)
542 BN_clear_free(grp->g);
543 if (grp->p != NULL)
544 BN_clear_free(grp->p);
545 if (grp->q != NULL)
546 BN_clear_free(grp->q);
547 bzero(grp, sizeof(*grp));
548 xfree(grp);
549}
550
551/* main() function for self-test */
552
Damien Miller01ed2272008-11-05 16:20:46 +1100553#ifdef SCHNORR_MAIN
554static void
555schnorr_selftest_one(const BIGNUM *grp_p, const BIGNUM *grp_q,
556 const BIGNUM *grp_g, const BIGNUM *x)
557{
558 BIGNUM *g_x;
559 u_char *sig;
560 u_int siglen;
561 BN_CTX *bn_ctx;
562
563 if ((bn_ctx = BN_CTX_new()) == NULL)
564 fatal("%s: BN_CTX_new", __func__);
565 if ((g_x = BN_new()) == NULL)
566 fatal("%s: BN_new", __func__);
567
568 if (BN_mod_exp(g_x, grp_g, x, grp_p, bn_ctx) == -1)
569 fatal("%s: g_x", __func__);
Damien Millercee85232009-03-06 00:58:22 +1100570 if (schnorr_sign_buf(grp_p, grp_q, grp_g, x, g_x, "junk", 4,
571 &sig, &siglen))
Damien Miller01ed2272008-11-05 16:20:46 +1100572 fatal("%s: schnorr_sign", __func__);
Damien Millercee85232009-03-06 00:58:22 +1100573 if (schnorr_verify_buf(grp_p, grp_q, grp_g, g_x, "junk", 4,
Damien Miller01ed2272008-11-05 16:20:46 +1100574 sig, siglen) != 1)
575 fatal("%s: verify fail", __func__);
Damien Millercee85232009-03-06 00:58:22 +1100576 if (schnorr_verify_buf(grp_p, grp_q, grp_g, g_x, "JUNK", 4,
Damien Miller01ed2272008-11-05 16:20:46 +1100577 sig, siglen) != 0)
578 fatal("%s: verify should have failed (bad ID)", __func__);
579 sig[4] ^= 1;
Damien Millercee85232009-03-06 00:58:22 +1100580 if (schnorr_verify_buf(grp_p, grp_q, grp_g, g_x, "junk", 4,
Damien Miller01ed2272008-11-05 16:20:46 +1100581 sig, siglen) != 0)
582 fatal("%s: verify should have failed (bit error)", __func__);
583 xfree(sig);
584 BN_free(g_x);
585 BN_CTX_free(bn_ctx);
586}
587
588static void
589schnorr_selftest(void)
590{
591 BIGNUM *x;
Damien Millercee85232009-03-06 00:58:22 +1100592 struct modp_group *grp;
Damien Miller01ed2272008-11-05 16:20:46 +1100593 u_int i;
594 char *hh;
595
596 grp = jpake_default_group();
597 if ((x = BN_new()) == NULL)
598 fatal("%s: BN_new", __func__);
599 SCHNORR_DEBUG_BN((grp->p, "%s: grp->p = ", __func__));
600 SCHNORR_DEBUG_BN((grp->q, "%s: grp->q = ", __func__));
601 SCHNORR_DEBUG_BN((grp->g, "%s: grp->g = ", __func__));
602
603 /* [1, 20) */
604 for (i = 1; i < 20; i++) {
605 printf("x = %u\n", i);
606 fflush(stdout);
607 if (BN_set_word(x, i) != 1)
608 fatal("%s: set x word", __func__);
609 schnorr_selftest_one(grp->p, grp->q, grp->g, x);
610 }
611
612 /* 100 x random [0, p) */
613 for (i = 0; i < 100; i++) {
614 if (BN_rand_range(x, grp->p) != 1)
615 fatal("%s: BN_rand_range", __func__);
616 hh = BN_bn2hex(x);
617 printf("x = (random) 0x%s\n", hh);
618 free(hh);
619 fflush(stdout);
620 schnorr_selftest_one(grp->p, grp->q, grp->g, x);
621 }
622
623 /* [q-20, q) */
624 if (BN_set_word(x, 20) != 1)
625 fatal("%s: BN_set_word (x = 20)", __func__);
626 if (BN_sub(x, grp->q, x) != 1)
627 fatal("%s: BN_sub (q - x)", __func__);
628 for (i = 0; i < 19; i++) {
629 hh = BN_bn2hex(x);
630 printf("x = (q - %d) 0x%s\n", 20 - i, hh);
631 free(hh);
632 fflush(stdout);
633 schnorr_selftest_one(grp->p, grp->q, grp->g, x);
634 if (BN_add(x, x, BN_value_one()) != 1)
635 fatal("%s: BN_add (x + 1)", __func__);
636 }
637 BN_free(x);
638}
639
640int
641main(int argc, char **argv)
642{
643 log_init(argv[0], SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_USER, 1);
644
645 schnorr_selftest();
646 return 0;
647}
648#endif
649