2 * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (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
10 /* ====================================================================
11 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
12 * Portions of this software developed by SUN MICROSYSTEMS, INC.,
13 * and contributed to the OpenSSL project.
16 #include <openssl/err.h>
17 #include <openssl/symhacks.h>
21 int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP
*group
,
23 const BIGNUM
*x_
, int y_bit
,
26 BN_CTX
*new_ctx
= NULL
;
27 BIGNUM
*tmp1
, *tmp2
, *x
, *y
;
30 /* clear error queue */
34 ctx
= new_ctx
= BN_CTX_new();
42 tmp1
= BN_CTX_get(ctx
);
43 tmp2
= BN_CTX_get(ctx
);
50 * Recover y. We have a Weierstrass equation
51 * y^2 = x^3 + a*x + b,
52 * so y is one of the square roots of x^3 + a*x + b.
56 if (!BN_nnmod(x
, x_
, group
->field
, ctx
))
58 if (group
->meth
->field_decode
== 0) {
59 /* field_{sqr,mul} work on standard representation */
60 if (!group
->meth
->field_sqr(group
, tmp2
, x_
, ctx
))
62 if (!group
->meth
->field_mul(group
, tmp1
, tmp2
, x_
, ctx
))
65 if (!BN_mod_sqr(tmp2
, x_
, group
->field
, ctx
))
67 if (!BN_mod_mul(tmp1
, tmp2
, x_
, group
->field
, ctx
))
71 /* tmp1 := tmp1 + a*x */
72 if (group
->a_is_minus3
) {
73 if (!BN_mod_lshift1_quick(tmp2
, x
, group
->field
))
75 if (!BN_mod_add_quick(tmp2
, tmp2
, x
, group
->field
))
77 if (!BN_mod_sub_quick(tmp1
, tmp1
, tmp2
, group
->field
))
80 if (group
->meth
->field_decode
) {
81 if (!group
->meth
->field_decode(group
, tmp2
, group
->a
, ctx
))
83 if (!BN_mod_mul(tmp2
, tmp2
, x
, group
->field
, ctx
))
86 /* field_mul works on standard representation */
87 if (!group
->meth
->field_mul(group
, tmp2
, group
->a
, x
, ctx
))
91 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
95 /* tmp1 := tmp1 + b */
96 if (group
->meth
->field_decode
) {
97 if (!group
->meth
->field_decode(group
, tmp2
, group
->b
, ctx
))
99 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
102 if (!BN_mod_add_quick(tmp1
, tmp1
, group
->b
, group
->field
))
106 if (!BN_mod_sqrt(y
, tmp1
, group
->field
, ctx
)) {
107 unsigned long err
= ERR_peek_last_error();
109 if (ERR_GET_LIB(err
) == ERR_LIB_BN
110 && ERR_GET_REASON(err
) == BN_R_NOT_A_SQUARE
) {
112 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
113 EC_R_INVALID_COMPRESSED_POINT
);
115 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
120 if (y_bit
!= BN_is_odd(y
)) {
124 kron
= BN_kronecker(x
, group
->field
, ctx
);
129 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
130 EC_R_INVALID_COMPRESSION_BIT
);
133 * BN_mod_sqrt() should have cought this error (not a square)
135 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
136 EC_R_INVALID_COMPRESSED_POINT
);
139 if (!BN_usub(y
, group
->field
, y
))
142 if (y_bit
!= BN_is_odd(y
)) {
143 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
144 ERR_R_INTERNAL_ERROR
);
148 if (!EC_POINT_set_affine_coordinates_GFp(group
, point
, x
, y
, ctx
))
155 BN_CTX_free(new_ctx
);
159 size_t 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
)
164 BN_CTX
*new_ctx
= NULL
;
167 size_t field_len
, i
, skip
;
169 if ((form
!= POINT_CONVERSION_COMPRESSED
)
170 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
171 && (form
!= POINT_CONVERSION_HYBRID
)) {
172 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_INVALID_FORM
);
176 if (EC_POINT_is_at_infinity(group
, point
)) {
177 /* encodes to a single 0 octet */
180 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
188 /* ret := required output buffer length */
189 field_len
= BN_num_bytes(group
->field
);
192 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
194 /* if 'buf' is NULL, just return required length */
197 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
202 ctx
= new_ctx
= BN_CTX_new();
214 if (!EC_POINT_get_affine_coordinates_GFp(group
, point
, x
, y
, ctx
))
217 if ((form
== POINT_CONVERSION_COMPRESSED
218 || form
== POINT_CONVERSION_HYBRID
) && BN_is_odd(y
))
225 skip
= field_len
- BN_num_bytes(x
);
226 if (skip
> field_len
) {
227 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
234 skip
= BN_bn2bin(x
, buf
+ i
);
236 if (i
!= 1 + field_len
) {
237 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
241 if (form
== POINT_CONVERSION_UNCOMPRESSED
242 || form
== POINT_CONVERSION_HYBRID
) {
243 skip
= field_len
- BN_num_bytes(y
);
244 if (skip
> field_len
) {
245 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
252 skip
= BN_bn2bin(y
, buf
+ i
);
257 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
264 BN_CTX_free(new_ctx
);
270 BN_CTX_free(new_ctx
);
274 int ec_GFp_simple_oct2point(const EC_GROUP
*group
, EC_POINT
*point
,
275 const unsigned char *buf
, size_t len
, BN_CTX
*ctx
)
277 point_conversion_form_t form
;
279 BN_CTX
*new_ctx
= NULL
;
281 size_t field_len
, enc_len
;
285 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_BUFFER_TOO_SMALL
);
291 if ((form
!= 0) && (form
!= POINT_CONVERSION_COMPRESSED
)
292 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
293 && (form
!= POINT_CONVERSION_HYBRID
)) {
294 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
297 if ((form
== 0 || form
== POINT_CONVERSION_UNCOMPRESSED
) && y_bit
) {
298 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
304 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
308 return EC_POINT_set_to_infinity(group
, point
);
311 field_len
= BN_num_bytes(group
->field
);
314 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
316 if (len
!= enc_len
) {
317 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
322 ctx
= new_ctx
= BN_CTX_new();
333 if (!BN_bin2bn(buf
+ 1, field_len
, x
))
335 if (BN_ucmp(x
, group
->field
) >= 0) {
336 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
340 if (form
== POINT_CONVERSION_COMPRESSED
) {
341 if (!EC_POINT_set_compressed_coordinates_GFp
342 (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_GFp is responsible for checking that
360 * the point is on the curve.
362 if (!EC_POINT_set_affine_coordinates_GFp(group
, point
, x
, y
, ctx
))
370 BN_CTX_free(new_ctx
);