2 * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
5 * Licensed under the OpenSSL license (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
;
25 /* clear error queue */
29 ctx
= new_ctx
= BN_CTX_new();
37 tmp1
= BN_CTX_get(ctx
);
38 tmp2
= BN_CTX_get(ctx
);
45 * Recover y. We have a Weierstrass equation
46 * y^2 = x^3 + a*x + b,
47 * so y is one of the square roots of x^3 + a*x + b.
51 if (!BN_nnmod(x
, x_
, group
->field
, ctx
))
53 if (group
->meth
->field_decode
== 0) {
54 /* field_{sqr,mul} work on standard representation */
55 if (!group
->meth
->field_sqr(group
, tmp2
, x_
, ctx
))
57 if (!group
->meth
->field_mul(group
, tmp1
, tmp2
, x_
, ctx
))
60 if (!BN_mod_sqr(tmp2
, x_
, group
->field
, ctx
))
62 if (!BN_mod_mul(tmp1
, tmp2
, x_
, group
->field
, ctx
))
66 /* tmp1 := tmp1 + a*x */
67 if (group
->a_is_minus3
) {
68 if (!BN_mod_lshift1_quick(tmp2
, x
, group
->field
))
70 if (!BN_mod_add_quick(tmp2
, tmp2
, x
, group
->field
))
72 if (!BN_mod_sub_quick(tmp1
, tmp1
, tmp2
, group
->field
))
75 if (group
->meth
->field_decode
) {
76 if (!group
->meth
->field_decode(group
, tmp2
, group
->a
, ctx
))
78 if (!BN_mod_mul(tmp2
, tmp2
, x
, group
->field
, ctx
))
81 /* field_mul works on standard representation */
82 if (!group
->meth
->field_mul(group
, tmp2
, group
->a
, x
, ctx
))
86 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
90 /* tmp1 := tmp1 + b */
91 if (group
->meth
->field_decode
) {
92 if (!group
->meth
->field_decode(group
, tmp2
, group
->b
, ctx
))
94 if (!BN_mod_add_quick(tmp1
, tmp1
, tmp2
, group
->field
))
97 if (!BN_mod_add_quick(tmp1
, tmp1
, group
->b
, group
->field
))
101 if (!BN_mod_sqrt(y
, tmp1
, group
->field
, ctx
)) {
102 unsigned long err
= ERR_peek_last_error();
104 if (ERR_GET_LIB(err
) == ERR_LIB_BN
105 && ERR_GET_REASON(err
) == BN_R_NOT_A_SQUARE
) {
107 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
108 EC_R_INVALID_COMPRESSED_POINT
);
110 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
115 if (y_bit
!= BN_is_odd(y
)) {
119 kron
= BN_kronecker(x
, group
->field
, ctx
);
124 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
125 EC_R_INVALID_COMPRESSION_BIT
);
128 * BN_mod_sqrt() should have caught this error (not a square)
130 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
131 EC_R_INVALID_COMPRESSED_POINT
);
134 if (!BN_usub(y
, group
->field
, y
))
137 if (y_bit
!= BN_is_odd(y
)) {
138 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES
,
139 ERR_R_INTERNAL_ERROR
);
143 if (!EC_POINT_set_affine_coordinates_GFp(group
, point
, x
, y
, ctx
))
150 BN_CTX_free(new_ctx
);
154 size_t ec_GFp_simple_point2oct(const EC_GROUP
*group
, const EC_POINT
*point
,
155 point_conversion_form_t form
,
156 unsigned char *buf
, size_t len
, BN_CTX
*ctx
)
159 BN_CTX
*new_ctx
= NULL
;
162 size_t field_len
, i
, skip
;
164 if ((form
!= POINT_CONVERSION_COMPRESSED
)
165 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
166 && (form
!= POINT_CONVERSION_HYBRID
)) {
167 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_INVALID_FORM
);
171 if (EC_POINT_is_at_infinity(group
, point
)) {
172 /* encodes to a single 0 octet */
175 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
183 /* ret := required output buffer length */
184 field_len
= BN_num_bytes(group
->field
);
187 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
189 /* if 'buf' is NULL, just return required length */
192 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, EC_R_BUFFER_TOO_SMALL
);
197 ctx
= new_ctx
= BN_CTX_new();
209 if (!EC_POINT_get_affine_coordinates_GFp(group
, point
, x
, y
, ctx
))
212 if ((form
== POINT_CONVERSION_COMPRESSED
213 || form
== POINT_CONVERSION_HYBRID
) && BN_is_odd(y
))
220 skip
= field_len
- BN_num_bytes(x
);
221 if (skip
> field_len
) {
222 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
229 skip
= BN_bn2bin(x
, buf
+ i
);
231 if (i
!= 1 + field_len
) {
232 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
236 if (form
== POINT_CONVERSION_UNCOMPRESSED
237 || form
== POINT_CONVERSION_HYBRID
) {
238 skip
= field_len
- BN_num_bytes(y
);
239 if (skip
> field_len
) {
240 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
247 skip
= BN_bn2bin(y
, buf
+ i
);
252 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT
, ERR_R_INTERNAL_ERROR
);
259 BN_CTX_free(new_ctx
);
265 BN_CTX_free(new_ctx
);
269 int ec_GFp_simple_oct2point(const EC_GROUP
*group
, EC_POINT
*point
,
270 const unsigned char *buf
, size_t len
, BN_CTX
*ctx
)
272 point_conversion_form_t form
;
274 BN_CTX
*new_ctx
= NULL
;
276 size_t field_len
, enc_len
;
280 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_BUFFER_TOO_SMALL
);
286 if ((form
!= 0) && (form
!= POINT_CONVERSION_COMPRESSED
)
287 && (form
!= POINT_CONVERSION_UNCOMPRESSED
)
288 && (form
!= POINT_CONVERSION_HYBRID
)) {
289 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
292 if ((form
== 0 || form
== POINT_CONVERSION_UNCOMPRESSED
) && y_bit
) {
293 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
299 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
303 return EC_POINT_set_to_infinity(group
, point
);
306 field_len
= BN_num_bytes(group
->field
);
309 POINT_CONVERSION_COMPRESSED
) ? 1 + field_len
: 1 + 2 * field_len
;
311 if (len
!= enc_len
) {
312 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
317 ctx
= new_ctx
= BN_CTX_new();
328 if (!BN_bin2bn(buf
+ 1, field_len
, x
))
330 if (BN_ucmp(x
, group
->field
) >= 0) {
331 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
335 if (form
== POINT_CONVERSION_COMPRESSED
) {
336 if (!EC_POINT_set_compressed_coordinates_GFp
337 (group
, point
, x
, y_bit
, ctx
))
340 if (!BN_bin2bn(buf
+ 1 + field_len
, field_len
, y
))
342 if (BN_ucmp(y
, group
->field
) >= 0) {
343 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
346 if (form
== POINT_CONVERSION_HYBRID
) {
347 if (y_bit
!= BN_is_odd(y
)) {
348 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT
, EC_R_INVALID_ENCODING
);
354 * EC_POINT_set_affine_coordinates_GFp is responsible for checking that
355 * the point is on the curve.
357 if (!EC_POINT_set_affine_coordinates_GFp(group
, point
, x
, y
, ctx
))
365 BN_CTX_free(new_ctx
);