2 * Copyright 2011-2020 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
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
12 * ECDSA low level APIs are deprecated for public use, but still ok for
15 #include "internal/deprecated.h"
17 #include <openssl/err.h>
18 #include <openssl/symhacks.h>
22 int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP
*group
,
24 const BIGNUM
*x_
, int y_bit
,
27 BN_CTX
*new_ctx
= NULL
;
28 BIGNUM
*tmp1
, *tmp2
, *x
, *y
;
32 /* clear error queue */
37 ctx
= new_ctx
= BN_CTX_new_ex(group
->libctx
);
45 tmp1
= BN_CTX_get(ctx
);
46 tmp2
= BN_CTX_get(ctx
);
53 * Recover y. We have a Weierstrass equation
54 * y^2 = x^3 + a*x + b,
55 * so y is one of the square roots of x^3 + a*x + b.
59 if (!BN_nnmod(x
, x_
, group
->field
, ctx
))
61 if (group
->meth
->field_decode
== 0) {
62 /* field_{sqr,mul} work on standard representation */
63 if (!group
->meth
->field_sqr(group
, tmp2
, x_
, ctx
))
65 if (!group
->meth
->field_mul(group
, tmp1
, tmp2
, x_
, ctx
))
68 if (!BN_mod_sqr(tmp2
, x_
, group
->field
, ctx
))
70 if (!BN_mod_mul(tmp1
, tmp2
, x_
, group
->field
, ctx
))
74 /* tmp1 := tmp1 + a*x */
75 if (group
->a_is_minus3
) {
76 if (!BN_mod_lshift1_quick(tmp2
, x
, group
->field
))
78 if (!BN_mod_add_quick(tmp2
, tmp2
, x
, group
->field
))
80 if (!BN_mod_sub_quick(tmp1
, tmp1
, tmp2
, group
->field
))
83 if (group
->meth
->field_decode
) {
84 if (!group
->meth
->field_decode(group
, tmp2
, group
->a
, ctx
))
86 if (!BN_mod_mul(tmp2
, tmp2
, x
, group
->field
, ctx
))
89 /* field_mul works on standard representation */
90 if (!group
->meth
->field_mul(group
, tmp2
, group
->a
, x
, ctx
))
94 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
98 /* tmp1 := tmp1 + b */
99 if (group
->meth
->field_decode
) {
100 if (!group
->meth
->field_decode(group
, tmp2
, group
->b
, ctx
))
102 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
105 if (!BN_mod_add_quick(tmp1
, tmp1
, group
->b
, group
->field
))
109 if (!BN_mod_sqrt(y
, tmp1
, group
->field
, ctx
)) {
111 unsigned long err
= ERR_peek_last_error();
113 if (ERR_GET_LIB(err
) == ERR_LIB_BN
114 && ERR_GET_REASON(err
) == BN_R_NOT_A_SQUARE
) {
116 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
117 EC_R_INVALID_COMPRESSED_POINT
);
121 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
127 if (y_bit
!= BN_is_odd(y
)) {
131 kron
= BN_kronecker(x
, group
->field
, ctx
);
136 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
137 EC_R_INVALID_COMPRESSION_BIT
);
140 * BN_mod_sqrt() should have caught this error (not a square)
142 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
143 EC_R_INVALID_COMPRESSED_POINT
);
146 if (!BN_usub(y
, group
->field
, y
))
149 if (y_bit
!= BN_is_odd(y
)) {
150 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
151 ERR_R_INTERNAL_ERROR
);
155 if (!EC_POINT_set_affine_coordinates(group
, point
, x
, y
, ctx
))
162 BN_CTX_free(new_ctx
);
166 size_t ec_GFp_simple_point2oct(const EC_GROUP
*group
, const EC_POINT
*point
,
167 point_conversion_form_t form
,
168 unsigned char *buf
, size_t len
, BN_CTX
*ctx
)
171 BN_CTX
*new_ctx
= NULL
;
174 size_t field_len
, i
, skip
;
176 if ((form
!= POINT_CONVERSION_COMPRESSED
)
177 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
178 && (form
!= POINT_CONVERSION_HYBRID
)) {
179 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_INVALID_FORM
);
183 if (EC_POINT_is_at_infinity(group
, point
)) {
184 /* encodes to a single 0 octet */
187 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
195 /* ret := required output buffer length */
196 field_len
= BN_num_bytes(group
->field
);
199 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
201 /* if 'buf' is NULL, just return required length */
204 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
209 ctx
= new_ctx
= BN_CTX_new_ex(group
->libctx
);
221 if (!EC_POINT_get_affine_coordinates(group
, point
, x
, y
, ctx
))
224 if ((form
== POINT_CONVERSION_COMPRESSED
225 || form
== POINT_CONVERSION_HYBRID
) && BN_is_odd(y
))
232 skip
= field_len
- BN_num_bytes(x
);
233 if (skip
> field_len
) {
234 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
241 skip
= BN_bn2bin(x
, buf
+ i
);
243 if (i
!= 1 + field_len
) {
244 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
248 if (form
== POINT_CONVERSION_UNCOMPRESSED
249 || form
== POINT_CONVERSION_HYBRID
) {
250 skip
= field_len
- BN_num_bytes(y
);
251 if (skip
> field_len
) {
252 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
259 skip
= BN_bn2bin(y
, buf
+ i
);
264 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
271 BN_CTX_free(new_ctx
);
277 BN_CTX_free(new_ctx
);
281 int ec_GFp_simple_oct2point(const EC_GROUP
*group
, EC_POINT
*point
,
282 const unsigned char *buf
, size_t len
, BN_CTX
*ctx
)
284 point_conversion_form_t form
;
286 BN_CTX
*new_ctx
= NULL
;
288 size_t field_len
, enc_len
;
292 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_BUFFER_TOO_SMALL
);
298 if ((form
!= 0) && (form
!= POINT_CONVERSION_COMPRESSED
)
299 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
300 && (form
!= POINT_CONVERSION_HYBRID
)) {
301 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
304 if ((form
== 0 || form
== POINT_CONVERSION_UNCOMPRESSED
) && y_bit
) {
305 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
311 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
315 return EC_POINT_set_to_infinity(group
, point
);
318 field_len
= BN_num_bytes(group
->field
);
321 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
323 if (len
!= enc_len
) {
324 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
329 ctx
= new_ctx
= BN_CTX_new_ex(group
->libctx
);
340 if (!BN_bin2bn(buf
+ 1, field_len
, x
))
342 if (BN_ucmp(x
, group
->field
) >= 0) {
343 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
347 if (form
== POINT_CONVERSION_COMPRESSED
) {
348 if (!EC_POINT_set_compressed_coordinates(group
, point
, x
, y_bit
, ctx
))
351 if (!BN_bin2bn(buf
+ 1 + field_len
, field_len
, y
))
353 if (BN_ucmp(y
, group
->field
) >= 0) {
354 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
357 if (form
== POINT_CONVERSION_HYBRID
) {
358 if (y_bit
!= BN_is_odd(y
)) {
359 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
365 * EC_POINT_set_affine_coordinates is responsible for checking that
366 * the point is on the curve.
368 if (!EC_POINT_set_affine_coordinates(group
, point
, x
, y
, ctx
))
376 BN_CTX_free(new_ctx
);