Coverage Report

Created: 2023-06-08 06:40

/src/openssl30/crypto/ec/ecp_oct.c
Line
Count
Source (jump to first uncovered line)
1
/*
2
 * Copyright 2011-2021 The OpenSSL Project Authors. All Rights Reserved.
3
 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
4
 *
5
 * Licensed under the Apache License 2.0 (the "License").  You may not use
6
 * this file except in compliance with the License.  You can obtain a copy
7
 * in the file LICENSE in the source distribution or at
8
 * https://www.openssl.org/source/license.html
9
 */
10
11
/*
12
 * ECDSA low level APIs are deprecated for public use, but still ok for
13
 * internal use.
14
 */
15
#include "internal/deprecated.h"
16
17
#include <openssl/err.h>
18
#include <openssl/symhacks.h>
19
20
#include "ec_local.h"
21
22
int ossl_ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group,
23
                                                  EC_POINT *point,
24
                                                  const BIGNUM *x_, int y_bit,
25
                                                  BN_CTX *ctx)
26
895
{
27
895
    BN_CTX *new_ctx = NULL;
28
895
    BIGNUM *tmp1, *tmp2, *x, *y;
29
895
    int ret = 0;
30
31
895
    if (ctx == NULL) {
32
0
        ctx = new_ctx = BN_CTX_new_ex(group->libctx);
33
0
        if (ctx == NULL)
34
0
            return 0;
35
0
    }
36
37
895
    y_bit = (y_bit != 0);
38
39
895
    BN_CTX_start(ctx);
40
895
    tmp1 = BN_CTX_get(ctx);
41
895
    tmp2 = BN_CTX_get(ctx);
42
895
    x = BN_CTX_get(ctx);
43
895
    y = BN_CTX_get(ctx);
44
895
    if (y == NULL)
45
0
        goto err;
46
47
    /*-
48
     * Recover y.  We have a Weierstrass equation
49
     *     y^2 = x^3 + a*x + b,
50
     * so  y  is one of the square roots of  x^3 + a*x + b.
51
     */
52
53
    /* tmp1 := x^3 */
54
895
    if (!BN_nnmod(x, x_, group->field, ctx))
55
0
        goto err;
56
895
    if (group->meth->field_decode == 0) {
57
        /* field_{sqr,mul} work on standard representation */
58
194
        if (!group->meth->field_sqr(group, tmp2, x_, ctx))
59
0
            goto err;
60
194
        if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
61
0
            goto err;
62
701
    } else {
63
701
        if (!BN_mod_sqr(tmp2, x_, group->field, ctx))
64
0
            goto err;
65
701
        if (!BN_mod_mul(tmp1, tmp2, x_, group->field, ctx))
66
0
            goto err;
67
701
    }
68
69
    /* tmp1 := tmp1 + a*x */
70
895
    if (group->a_is_minus3) {
71
530
        if (!BN_mod_lshift1_quick(tmp2, x, group->field))
72
0
            goto err;
73
530
        if (!BN_mod_add_quick(tmp2, tmp2, x, group->field))
74
0
            goto err;
75
530
        if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, group->field))
76
0
            goto err;
77
530
    } else {
78
365
        if (group->meth->field_decode) {
79
365
            if (!group->meth->field_decode(group, tmp2, group->a, ctx))
80
0
                goto err;
81
365
            if (!BN_mod_mul(tmp2, tmp2, x, group->field, ctx))
82
0
                goto err;
83
365
        } else {
84
            /* field_mul works on standard representation */
85
0
            if (!group->meth->field_mul(group, tmp2, group->a, x, ctx))
86
0
                goto err;
87
0
        }
88
89
365
        if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
90
0
            goto err;
91
365
    }
92
93
    /* tmp1 := tmp1 + b */
94
895
    if (group->meth->field_decode) {
95
701
        if (!group->meth->field_decode(group, tmp2, group->b, ctx))
96
0
            goto err;
97
701
        if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
98
0
            goto err;
99
701
    } else {
100
194
        if (!BN_mod_add_quick(tmp1, tmp1, group->b, group->field))
101
0
            goto err;
102
194
    }
103
104
895
    ERR_set_mark();
105
895
    if (!BN_mod_sqrt(y, tmp1, group->field, ctx)) {
106
337
#ifndef FIPS_MODULE
107
337
        unsigned long err = ERR_peek_last_error();
108
109
337
        if (ERR_GET_LIB(err) == ERR_LIB_BN
110
337
            && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
111
337
            ERR_pop_to_mark();
112
337
            ERR_raise(ERR_LIB_EC, EC_R_INVALID_COMPRESSED_POINT);
113
337
        } else
114
0
#endif
115
0
        {
116
0
            ERR_clear_last_mark();
117
0
            ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
118
0
        }
119
337
        goto err;
120
337
    }
121
558
    ERR_clear_last_mark();
122
123
558
    if (y_bit != BN_is_odd(y)) {
124
273
        if (BN_is_zero(y)) {
125
0
            int kron;
126
127
0
            kron = BN_kronecker(x, group->field, ctx);
128
0
            if (kron == -2)
129
0
                goto err;
130
131
0
            if (kron == 1)
132
0
                ERR_raise(ERR_LIB_EC, EC_R_INVALID_COMPRESSION_BIT);
133
0
            else
134
                /*
135
                 * BN_mod_sqrt() should have caught this error (not a square)
136
                 */
137
0
                ERR_raise(ERR_LIB_EC, EC_R_INVALID_COMPRESSED_POINT);
138
0
            goto err;
139
0
        }
140
273
        if (!BN_usub(y, group->field, y))
141
0
            goto err;
142
273
    }
143
558
    if (y_bit != BN_is_odd(y)) {
144
0
        ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
145
0
        goto err;
146
0
    }
147
148
558
    if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
149
0
        goto err;
150
151
558
    ret = 1;
152
153
895
 err:
154
895
    BN_CTX_end(ctx);
155
895
    BN_CTX_free(new_ctx);
156
895
    return ret;
157
558
}
158
159
size_t ossl_ec_GFp_simple_point2oct(const EC_GROUP *group, const EC_POINT *point,
160
                                    point_conversion_form_t form,
161
                                    unsigned char *buf, size_t len, BN_CTX *ctx)
162
127
{
163
127
    size_t ret;
164
127
    BN_CTX *new_ctx = NULL;
165
127
    int used_ctx = 0;
166
127
    BIGNUM *x, *y;
167
127
    size_t field_len, i, skip;
168
169
127
    if ((form != POINT_CONVERSION_COMPRESSED)
170
127
        && (form != POINT_CONVERSION_UNCOMPRESSED)
171
127
        && (form != POINT_CONVERSION_HYBRID)) {
172
5
        ERR_raise(ERR_LIB_EC, EC_R_INVALID_FORM);
173
5
        goto err;
174
5
    }
175
176
122
    if (EC_POINT_is_at_infinity(group, point)) {
177
        /* encodes to a single 0 octet */
178
0
        if (buf != NULL) {
179
0
            if (len < 1) {
180
0
                ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
181
0
                return 0;
182
0
            }
183
0
            buf[0] = 0;
184
0
        }
185
0
        return 1;
186
0
    }
187
188
    /* ret := required output buffer length */
189
122
    field_len = BN_num_bytes(group->field);
190
122
    ret =
191
122
        (form ==
192
122
         POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
193
194
    /* if 'buf' is NULL, just return required length */
195
122
    if (buf != NULL) {
196
61
        if (len < ret) {
197
0
            ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
198
0
            goto err;
199
0
        }
200
201
61
        if (ctx == NULL) {
202
58
            ctx = new_ctx = BN_CTX_new_ex(group->libctx);
203
58
            if (ctx == NULL)
204
0
                return 0;
205
58
        }
206
207
61
        BN_CTX_start(ctx);
208
61
        used_ctx = 1;
209
61
        x = BN_CTX_get(ctx);
210
61
        y = BN_CTX_get(ctx);
211
61
        if (y == NULL)
212
0
            goto err;
213
214
61
        if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
215
0
            goto err;
216
217
61
        if ((form == POINT_CONVERSION_COMPRESSED
218
61
             || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
219
13
            buf[0] = form + 1;
220
48
        else
221
48
            buf[0] = form;
222
223
61
        i = 1;
224
225
61
        skip = field_len - BN_num_bytes(x);
226
61
        if (skip > field_len) {
227
0
            ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
228
0
            goto err;
229
0
        }
230
666
        while (skip > 0) {
231
605
            buf[i++] = 0;
232
605
            skip--;
233
605
        }
234
61
        skip = BN_bn2bin(x, buf + i);
235
61
        i += skip;
236
61
        if (i != 1 + field_len) {
237
0
            ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
238
0
            goto err;
239
0
        }
240
241
61
        if (form == POINT_CONVERSION_UNCOMPRESSED
242
61
            || form == POINT_CONVERSION_HYBRID) {
243
9
            skip = field_len - BN_num_bytes(y);
244
9
            if (skip > field_len) {
245
0
                ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
246
0
                goto err;
247
0
            }
248
169
            while (skip > 0) {
249
160
                buf[i++] = 0;
250
160
                skip--;
251
160
            }
252
9
            skip = BN_bn2bin(y, buf + i);
253
9
            i += skip;
254
9
        }
255
256
61
        if (i != ret) {
257
0
            ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
258
0
            goto err;
259
0
        }
260
61
    }
261
262
122
    if (used_ctx)
263
61
        BN_CTX_end(ctx);
264
122
    BN_CTX_free(new_ctx);
265
122
    return ret;
266
267
5
 err:
268
5
    if (used_ctx)
269
0
        BN_CTX_end(ctx);
270
5
    BN_CTX_free(new_ctx);
271
5
    return 0;
272
122
}
273
274
int ossl_ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
275
                                 const unsigned char *buf, size_t len,
276
                                 BN_CTX *ctx)
277
1.59k
{
278
1.59k
    point_conversion_form_t form;
279
1.59k
    int y_bit;
280
1.59k
    BN_CTX *new_ctx = NULL;
281
1.59k
    BIGNUM *x, *y;
282
1.59k
    size_t field_len, enc_len;
283
1.59k
    int ret = 0;
284
285
1.59k
    if (len == 0) {
286
25
        ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
287
25
        return 0;
288
25
    }
289
1.57k
    form = buf[0];
290
1.57k
    y_bit = form & 1;
291
1.57k
    form = form & ~1U;
292
1.57k
    if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
293
1.57k
        && (form != POINT_CONVERSION_UNCOMPRESSED)
294
1.57k
        && (form != POINT_CONVERSION_HYBRID)) {
295
57
        ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
296
57
        return 0;
297
57
    }
298
1.51k
    if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
299
20
        ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
300
20
        return 0;
301
20
    }
302
303
1.49k
    if (form == 0) {
304
73
        if (len != 1) {
305
49
            ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
306
49
            return 0;
307
49
        }
308
309
24
        return EC_POINT_set_to_infinity(group, point);
310
73
    }
311
312
1.42k
    field_len = BN_num_bytes(group->field);
313
1.42k
    enc_len =
314
1.42k
        (form ==
315
1.42k
         POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
316
317
1.42k
    if (len != enc_len) {
318
35
        ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
319
35
        return 0;
320
35
    }
321
322
1.38k
    if (ctx == NULL) {
323
1.38k
        ctx = new_ctx = BN_CTX_new_ex(group->libctx);
324
1.38k
        if (ctx == NULL)
325
0
            return 0;
326
1.38k
    }
327
328
1.38k
    BN_CTX_start(ctx);
329
1.38k
    x = BN_CTX_get(ctx);
330
1.38k
    y = BN_CTX_get(ctx);
331
1.38k
    if (y == NULL)
332
0
        goto err;
333
334
1.38k
    if (!BN_bin2bn(buf + 1, field_len, x))
335
0
        goto err;
336
1.38k
    if (BN_ucmp(x, group->field) >= 0) {
337
8
        ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
338
8
        goto err;
339
8
    }
340
341
1.37k
    if (form == POINT_CONVERSION_COMPRESSED) {
342
895
        if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
343
337
            goto err;
344
895
    } else {
345
482
        if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
346
0
            goto err;
347
482
        if (BN_ucmp(y, group->field) >= 0) {
348
8
            ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
349
8
            goto err;
350
8
        }
351
474
        if (form == POINT_CONVERSION_HYBRID) {
352
342
            if (y_bit != BN_is_odd(y)) {
353
21
                ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
354
21
                goto err;
355
21
            }
356
342
        }
357
358
        /*
359
         * EC_POINT_set_affine_coordinates is responsible for checking that
360
         * the point is on the curve.
361
         */
362
453
        if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
363
104
            goto err;
364
453
    }
365
366
907
    ret = 1;
367
368
1.38k
 err:
369
1.38k
    BN_CTX_end(ctx);
370
1.38k
    BN_CTX_free(new_ctx);
371
1.38k
    return ret;
372
907
}