2 * Copyright 2011-2018 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
11 #include <openssl/err.h>
12 #include <openssl/symhacks.h>
16 int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP
*group
,
18 const BIGNUM
*x_
, int y_bit
,
21 BN_CTX
*new_ctx
= NULL
;
22 BIGNUM
*tmp1
, *tmp2
, *x
, *y
;
26 /* clear error queue */
31 ctx
= new_ctx
= BN_CTX_new_ex(group
->libctx
);
39 tmp1
= BN_CTX_get(ctx
);
40 tmp2
= BN_CTX_get(ctx
);
47 * Recover y. We have a Weierstrass equation
48 * y^2 = x^3 + a*x + b,
49 * so y is one of the square roots of x^3 + a*x + b.
53 if (!BN_nnmod(x
, x_
, group
->field
, ctx
))
55 if (group
->meth
->field_decode
== 0) {
56 /* field_{sqr,mul} work on standard representation */
57 if (!group
->meth
->field_sqr(group
, tmp2
, x_
, ctx
))
59 if (!group
->meth
->field_mul(group
, tmp1
, tmp2
, x_
, ctx
))
62 if (!BN_mod_sqr(tmp2
, x_
, group
->field
, ctx
))
64 if (!BN_mod_mul(tmp1
, tmp2
, x_
, group
->field
, ctx
))
68 /* tmp1 := tmp1 + a*x */
69 if (group
->a_is_minus3
) {
70 if (!BN_mod_lshift1_quick(tmp2
, x
, group
->field
))
72 if (!BN_mod_add_quick(tmp2
, tmp2
, x
, group
->field
))
74 if (!BN_mod_sub_quick(tmp1
, tmp1
, tmp2
, group
->field
))
77 if (group
->meth
->field_decode
) {
78 if (!group
->meth
->field_decode(group
, tmp2
, group
->a
, ctx
))
80 if (!BN_mod_mul(tmp2
, tmp2
, x
, group
->field
, ctx
))
83 /* field_mul works on standard representation */
84 if (!group
->meth
->field_mul(group
, tmp2
, group
->a
, x
, ctx
))
88 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
92 /* tmp1 := tmp1 + b */
93 if (group
->meth
->field_decode
) {
94 if (!group
->meth
->field_decode(group
, tmp2
, group
->b
, ctx
))
96 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
99 if (!BN_mod_add_quick(tmp1
, tmp1
, group
->b
, group
->field
))
103 if (!BN_mod_sqrt(y
, tmp1
, group
->field
, ctx
)) {
105 unsigned long err
= ERR_peek_last_error();
107 if (ERR_GET_LIB(err
) == ERR_LIB_BN
108 && ERR_GET_REASON(err
) == BN_R_NOT_A_SQUARE
) {
110 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
111 EC_R_INVALID_COMPRESSED_POINT
);
115 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
121 if (y_bit
!= BN_is_odd(y
)) {
125 kron
= BN_kronecker(x
, group
->field
, ctx
);
130 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
131 EC_R_INVALID_COMPRESSION_BIT
);
134 * BN_mod_sqrt() should have caught this error (not a square)
136 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
137 EC_R_INVALID_COMPRESSED_POINT
);
140 if (!BN_usub(y
, group
->field
, y
))
143 if (y_bit
!= BN_is_odd(y
)) {
144 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
145 ERR_R_INTERNAL_ERROR
);
149 if (!EC_POINT_set_affine_coordinates(group
, point
, x
, y
, ctx
))
156 BN_CTX_free(new_ctx
);
160 size_t ec_GFp_simple_point2oct(const EC_GROUP
*group
, const EC_POINT
*point
,
161 point_conversion_form_t form
,
162 unsigned char *buf
, size_t len
, BN_CTX
*ctx
)
165 BN_CTX
*new_ctx
= NULL
;
168 size_t field_len
, i
, skip
;
170 if ((form
!= POINT_CONVERSION_COMPRESSED
)
171 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
172 && (form
!= POINT_CONVERSION_HYBRID
)) {
173 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_INVALID_FORM
);
177 if (EC_POINT_is_at_infinity(group
, point
)) {
178 /* encodes to a single 0 octet */
181 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
189 /* ret := required output buffer length */
190 field_len
= BN_num_bytes(group
->field
);
193 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
195 /* if 'buf' is NULL, just return required length */
198 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
203 ctx
= new_ctx
= BN_CTX_new_ex(group
->libctx
);
215 if (!EC_POINT_get_affine_coordinates(group
, point
, x
, y
, ctx
))
218 if ((form
== POINT_CONVERSION_COMPRESSED
219 || form
== POINT_CONVERSION_HYBRID
) && BN_is_odd(y
))
226 skip
= field_len
- BN_num_bytes(x
);
227 if (skip
> field_len
) {
228 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
235 skip
= BN_bn2bin(x
, buf
+ i
);
237 if (i
!= 1 + field_len
) {
238 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
242 if (form
== POINT_CONVERSION_UNCOMPRESSED
243 || form
== POINT_CONVERSION_HYBRID
) {
244 skip
= field_len
- BN_num_bytes(y
);
245 if (skip
> field_len
) {
246 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
253 skip
= BN_bn2bin(y
, buf
+ i
);
258 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
265 BN_CTX_free(new_ctx
);
271 BN_CTX_free(new_ctx
);
275 int ec_GFp_simple_oct2point(const EC_GROUP
*group
, EC_POINT
*point
,
276 const unsigned char *buf
, size_t len
, BN_CTX
*ctx
)
278 point_conversion_form_t form
;
280 BN_CTX
*new_ctx
= NULL
;
282 size_t field_len
, enc_len
;
286 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_BUFFER_TOO_SMALL
);
292 if ((form
!= 0) && (form
!= POINT_CONVERSION_COMPRESSED
)
293 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
294 && (form
!= POINT_CONVERSION_HYBRID
)) {
295 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
298 if ((form
== 0 || form
== POINT_CONVERSION_UNCOMPRESSED
) && y_bit
) {
299 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
305 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
309 return EC_POINT_set_to_infinity(group
, point
);
312 field_len
= BN_num_bytes(group
->field
);
315 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
317 if (len
!= enc_len
) {
318 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
323 ctx
= new_ctx
= BN_CTX_new_ex(group
->libctx
);
334 if (!BN_bin2bn(buf
+ 1, field_len
, x
))
336 if (BN_ucmp(x
, group
->field
) >= 0) {
337 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
341 if (form
== POINT_CONVERSION_COMPRESSED
) {
342 if (!EC_POINT_set_compressed_coordinates(group
, point
, x
, y_bit
, ctx
))
345 if (!BN_bin2bn(buf
+ 1 + field_len
, field_len
, y
))
347 if (BN_ucmp(y
, group
->field
) >= 0) {
348 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
351 if (form
== POINT_CONVERSION_HYBRID
) {
352 if (y_bit
!= BN_is_odd(y
)) {
353 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
359 * EC_POINT_set_affine_coordinates is responsible for checking that
360 * the point is on the curve.
362 if (!EC_POINT_set_affine_coordinates(group
, point
, x
, y
, ctx
))
370 BN_CTX_free(new_ctx
);