ecdsa_ossl.c revision 1.1.1.6 
1/*
2 * Copyright 2002-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10/*
11 * ECDSA low level APIs are deprecated for public use, but still ok for
12 * internal use.
13 */
14#include "internal/deprecated.h"
15
16#include <string.h>
17#include <openssl/err.h>
18#include <openssl/obj_mac.h>
19#include <openssl/rand.h>
20#include "crypto/bn.h"
21#include "ec_local.h"
22
23int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
24                          BIGNUM **rp)
25{
26    if (eckey->group->meth->ecdsa_sign_setup == NULL) {
27        ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
28        return 0;
29    }
30
31    return eckey->group->meth->ecdsa_sign_setup(eckey, ctx_in, kinvp, rp);
32}
33
34ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
35                               const BIGNUM *in_kinv, const BIGNUM *in_r,
36                               EC_KEY *eckey)
37{
38    if (eckey->group->meth->ecdsa_sign_sig == NULL) {
39        ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
40        return NULL;
41    }
42
43    return eckey->group->meth->ecdsa_sign_sig(dgst, dgst_len,
44                                              in_kinv, in_r, eckey);
45}
46
47int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
48                          const ECDSA_SIG *sig, EC_KEY *eckey)
49{
50    if (eckey->group->meth->ecdsa_verify_sig == NULL) {
51        ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
52        return 0;
53    }
54
55    return eckey->group->meth->ecdsa_verify_sig(dgst, dgst_len, sig, eckey);
56}
57
58int ossl_ecdsa_sign(int type, const unsigned char *dgst, int dlen,
59                    unsigned char *sig, unsigned int *siglen,
60                    const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)
61{
62    ECDSA_SIG *s;
63
64    s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
65    if (s == NULL) {
66        *siglen = 0;
67        return 0;
68    }
69    *siglen = i2d_ECDSA_SIG(s, &sig);
70    ECDSA_SIG_free(s);
71    return 1;
72}
73
74static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
75                            BIGNUM **kinvp, BIGNUM **rp,
76                            const unsigned char *dgst, int dlen)
77{
78    BN_CTX *ctx = NULL;
79    BIGNUM *k = NULL, *r = NULL, *X = NULL;
80    const BIGNUM *order;
81    EC_POINT *tmp_point = NULL;
82    const EC_GROUP *group;
83    int ret = 0;
84    int order_bits;
85    const BIGNUM *priv_key;
86
87    if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
88        ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
89        return 0;
90    }
91    if ((priv_key = EC_KEY_get0_private_key(eckey)) == NULL) {
92        ERR_raise(ERR_LIB_EC, EC_R_MISSING_PRIVATE_KEY);
93        return 0;
94    }
95
96    if (!EC_KEY_can_sign(eckey)) {
97        ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
98        return 0;
99    }
100
101    if ((ctx = ctx_in) == NULL) {
102        if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL) {
103            ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
104            return 0;
105        }
106    }
107
108    k = BN_secure_new();        /* this value is later returned in *kinvp */
109    r = BN_new();               /* this value is later returned in *rp */
110    X = BN_new();
111    if (k == NULL || r == NULL || X == NULL) {
112        ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
113        goto err;
114    }
115    if ((tmp_point = EC_POINT_new(group)) == NULL) {
116        ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
117        goto err;
118    }
119    order = EC_GROUP_get0_order(group);
120
121    /* Preallocate space */
122    order_bits = BN_num_bits(order);
123    if (!BN_set_bit(k, order_bits)
124        || !BN_set_bit(r, order_bits)
125        || !BN_set_bit(X, order_bits))
126        goto err;
127
128    do {
129        /* get random k */
130        do {
131            if (dgst != NULL) {
132                if (!BN_generate_dsa_nonce(k, order, priv_key,
133                                           dgst, dlen, ctx)) {
134                    ERR_raise(ERR_LIB_EC, EC_R_RANDOM_NUMBER_GENERATION_FAILED);
135                    goto err;
136                }
137            } else {
138                if (!BN_priv_rand_range_ex(k, order, 0, ctx)) {
139                    ERR_raise(ERR_LIB_EC, EC_R_RANDOM_NUMBER_GENERATION_FAILED);
140                    goto err;
141                }
142            }
143        } while (BN_is_zero(k));
144
145        /* compute r the x-coordinate of generator * k */
146        if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
147            ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
148            goto err;
149        }
150
151        if (!EC_POINT_get_affine_coordinates(group, tmp_point, X, NULL, ctx)) {
152            ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
153            goto err;
154        }
155
156        if (!BN_nnmod(r, X, order, ctx)) {
157            ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
158            goto err;
159        }
160    } while (BN_is_zero(r));
161
162    /* compute the inverse of k */
163    if (!ossl_ec_group_do_inverse_ord(group, k, k, ctx)) {
164        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
165        goto err;
166    }
167
168    /* clear old values if necessary */
169    BN_clear_free(*rp);
170    BN_clear_free(*kinvp);
171    /* save the pre-computed values  */
172    *rp = r;
173    *kinvp = k;
174    ret = 1;
175 err:
176    if (!ret) {
177        BN_clear_free(k);
178        BN_clear_free(r);
179    }
180    if (ctx != ctx_in)
181        BN_CTX_free(ctx);
182    EC_POINT_free(tmp_point);
183    BN_clear_free(X);
184    return ret;
185}
186
187int ossl_ecdsa_simple_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
188                                 BIGNUM **rp)
189{
190    return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
191}
192
193ECDSA_SIG *ossl_ecdsa_simple_sign_sig(const unsigned char *dgst, int dgst_len,
194                                      const BIGNUM *in_kinv, const BIGNUM *in_r,
195                                      EC_KEY *eckey)
196{
197    int ok = 0, i;
198    BIGNUM *kinv = NULL, *s, *m = NULL;
199    const BIGNUM *order, *ckinv;
200    BN_CTX *ctx = NULL;
201    const EC_GROUP *group;
202    ECDSA_SIG *ret;
203    const BIGNUM *priv_key;
204
205    group = EC_KEY_get0_group(eckey);
206    priv_key = EC_KEY_get0_private_key(eckey);
207
208    if (group == NULL) {
209        ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
210        return NULL;
211    }
212    if (priv_key == NULL) {
213        ERR_raise(ERR_LIB_EC, EC_R_MISSING_PRIVATE_KEY);
214        return NULL;
215    }
216
217    if (!EC_KEY_can_sign(eckey)) {
218        ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
219        return NULL;
220    }
221
222    ret = ECDSA_SIG_new();
223    if (ret == NULL) {
224        ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
225        return NULL;
226    }
227    ret->r = BN_new();
228    ret->s = BN_new();
229    if (ret->r == NULL || ret->s == NULL) {
230        ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
231        goto err;
232    }
233    s = ret->s;
234
235    if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL
236        || (m = BN_new()) == NULL) {
237        ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
238        goto err;
239    }
240
241    order = EC_GROUP_get0_order(group);
242    i = BN_num_bits(order);
243    /*
244     * Need to truncate digest if it is too long: first truncate whole bytes.
245     */
246    if (8 * dgst_len > i)
247        dgst_len = (i + 7) / 8;
248    if (!BN_bin2bn(dgst, dgst_len, m)) {
249        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
250        goto err;
251    }
252    /* If still too long, truncate remaining bits with a shift */
253    if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
254        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
255        goto err;
256    }
257    do {
258        if (in_kinv == NULL || in_r == NULL) {
259            if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
260                ERR_raise(ERR_LIB_EC, ERR_R_ECDSA_LIB);
261                goto err;
262            }
263            ckinv = kinv;
264        } else {
265            ckinv = in_kinv;
266            if (BN_copy(ret->r, in_r) == NULL) {
267                ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
268                goto err;
269            }
270        }
271
272        /*
273         * With only one multiplicant being in Montgomery domain
274         * multiplication yields real result without post-conversion.
275         * Also note that all operations but last are performed with
276         * zero-padded vectors. Last operation, BN_mod_mul_montgomery
277         * below, returns user-visible value with removed zero padding.
278         */
279        if (!bn_to_mont_fixed_top(s, ret->r, group->mont_data, ctx)
280            || !bn_mul_mont_fixed_top(s, s, priv_key, group->mont_data, ctx)) {
281            ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
282            goto err;
283        }
284        if (!bn_mod_add_fixed_top(s, s, m, order)) {
285            ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
286            goto err;
287        }
288        /*
289         * |s| can still be larger than modulus, because |m| can be. In
290         * such case we count on Montgomery reduction to tie it up.
291         */
292        if (!bn_to_mont_fixed_top(s, s, group->mont_data, ctx)
293            || !BN_mod_mul_montgomery(s, s, ckinv, group->mont_data, ctx)) {
294            ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
295            goto err;
296        }
297
298        if (BN_is_zero(s)) {
299            /*
300             * if kinv and r have been supplied by the caller, don't
301             * generate new kinv and r values
302             */
303            if (in_kinv != NULL && in_r != NULL) {
304                ERR_raise(ERR_LIB_EC, EC_R_NEED_NEW_SETUP_VALUES);
305                goto err;
306            }
307        } else {
308            /* s != 0 => we have a valid signature */
309            break;
310        }
311    } while (1);
312
313    ok = 1;
314 err:
315    if (!ok) {
316        ECDSA_SIG_free(ret);
317        ret = NULL;
318    }
319    BN_CTX_free(ctx);
320    BN_clear_free(m);
321    BN_clear_free(kinv);
322    return ret;
323}
324
325/*-
326 * returns
327 *      1: correct signature
328 *      0: incorrect signature
329 *     -1: error
330 */
331int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
332                      const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
333{
334    ECDSA_SIG *s;
335    const unsigned char *p = sigbuf;
336    unsigned char *der = NULL;
337    int derlen = -1;
338    int ret = -1;
339
340    s = ECDSA_SIG_new();
341    if (s == NULL)
342        return ret;
343    if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
344        goto err;
345    /* Ensure signature uses DER and doesn't have trailing garbage */
346    derlen = i2d_ECDSA_SIG(s, &der);
347    if (derlen != sig_len || memcmp(sigbuf, der, derlen) != 0)
348        goto err;
349    ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
350 err:
351    OPENSSL_free(der);
352    ECDSA_SIG_free(s);
353    return ret;
354}
355
356int ossl_ecdsa_simple_verify_sig(const unsigned char *dgst, int dgst_len,
357                                 const ECDSA_SIG *sig, EC_KEY *eckey)
358{
359    int ret = -1, i;
360    BN_CTX *ctx;
361    const BIGNUM *order;
362    BIGNUM *u1, *u2, *m, *X;
363    EC_POINT *point = NULL;
364    const EC_GROUP *group;
365    const EC_POINT *pub_key;
366
367    /* check input values */
368    if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
369        (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
370        ERR_raise(ERR_LIB_EC, EC_R_MISSING_PARAMETERS);
371        return -1;
372    }
373
374    if (!EC_KEY_can_sign(eckey)) {
375        ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
376        return -1;
377    }
378
379    ctx = BN_CTX_new_ex(eckey->libctx);
380    if (ctx == NULL) {
381        ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
382        return -1;
383    }
384    BN_CTX_start(ctx);
385    u1 = BN_CTX_get(ctx);
386    u2 = BN_CTX_get(ctx);
387    m = BN_CTX_get(ctx);
388    X = BN_CTX_get(ctx);
389    if (X == NULL) {
390        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
391        goto err;
392    }
393
394    order = EC_GROUP_get0_order(group);
395    if (order == NULL) {
396        ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
397        goto err;
398    }
399
400    if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
401        BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
402        BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
403        ERR_raise(ERR_LIB_EC, EC_R_BAD_SIGNATURE);
404        ret = 0;                /* signature is invalid */
405        goto err;
406    }
407    /* calculate tmp1 = inv(S) mod order */
408    if (!ossl_ec_group_do_inverse_ord(group, u2, sig->s, ctx)) {
409        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
410        goto err;
411    }
412    /* digest -> m */
413    i = BN_num_bits(order);
414    /*
415     * Need to truncate digest if it is too long: first truncate whole bytes.
416     */
417    if (8 * dgst_len > i)
418        dgst_len = (i + 7) / 8;
419    if (!BN_bin2bn(dgst, dgst_len, m)) {
420        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
421        goto err;
422    }
423    /* If still too long truncate remaining bits with a shift */
424    if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
425        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
426        goto err;
427    }
428    /* u1 = m * tmp mod order */
429    if (!BN_mod_mul(u1, m, u2, order, ctx)) {
430        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
431        goto err;
432    }
433    /* u2 = r * w mod q */
434    if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
435        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
436        goto err;
437    }
438
439    if ((point = EC_POINT_new(group)) == NULL) {
440        ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
441        goto err;
442    }
443    if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
444        ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
445        goto err;
446    }
447
448    if (!EC_POINT_get_affine_coordinates(group, point, X, NULL, ctx)) {
449        ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
450        goto err;
451    }
452
453    if (!BN_nnmod(u1, X, order, ctx)) {
454        ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
455        goto err;
456    }
457    /*  if the signature is correct u1 is equal to sig->r */
458    ret = (BN_ucmp(u1, sig->r) == 0);
459 err:
460    BN_CTX_end(ctx);
461    BN_CTX_free(ctx);
462    EC_POINT_free(point);
463    return ret;
464}
465