Bitcoin Core  22.99.0
P2P Digital Currency
main_impl.h
Go to the documentation of this file.
1 /***********************************************************************
2  * Copyright (c) 2020 Jonas Nick *
3  * Distributed under the MIT software license, see the accompanying *
4  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
5  ***********************************************************************/
6 
7 #ifndef SECP256K1_MODULE_EXTRAKEYS_MAIN_H
8 #define SECP256K1_MODULE_EXTRAKEYS_MAIN_H
9 
10 #include "../../../include/secp256k1.h"
11 #include "../../../include/secp256k1_extrakeys.h"
12 
14  return secp256k1_pubkey_load(ctx, ge, (const secp256k1_pubkey *) pubkey);
15 }
16 
19 }
20 
21 int secp256k1_xonly_pubkey_parse(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pubkey, const unsigned char *input32) {
22  secp256k1_ge pk;
23  secp256k1_fe x;
24 
25  VERIFY_CHECK(ctx != NULL);
26  ARG_CHECK(pubkey != NULL);
27  memset(pubkey, 0, sizeof(*pubkey));
28  ARG_CHECK(input32 != NULL);
29 
30  if (!secp256k1_fe_set_b32(&x, input32)) {
31  return 0;
32  }
33  if (!secp256k1_ge_set_xo_var(&pk, &x, 0)) {
34  return 0;
35  }
37  return 0;
38  }
39  secp256k1_xonly_pubkey_save(pubkey, &pk);
40  return 1;
41 }
42 
43 int secp256k1_xonly_pubkey_serialize(const secp256k1_context* ctx, unsigned char *output32, const secp256k1_xonly_pubkey *pubkey) {
44  secp256k1_ge pk;
45 
46  VERIFY_CHECK(ctx != NULL);
47  ARG_CHECK(output32 != NULL);
48  memset(output32, 0, 32);
49  ARG_CHECK(pubkey != NULL);
50 
51  if (!secp256k1_xonly_pubkey_load(ctx, &pk, pubkey)) {
52  return 0;
53  }
54  secp256k1_fe_get_b32(output32, &pk.x);
55  return 1;
56 }
57 
59  unsigned char out[2][32];
60  const secp256k1_xonly_pubkey* pk[2];
61  int i;
62 
63  VERIFY_CHECK(ctx != NULL);
64  pk[0] = pk0; pk[1] = pk1;
65  for (i = 0; i < 2; i++) {
66  /* If the public key is NULL or invalid, xonly_pubkey_serialize will
67  * call the illegal_callback and return 0. In that case we will
68  * serialize the key as all zeros which is less than any valid public
69  * key. This results in consistent comparisons even if NULL or invalid
70  * pubkeys are involved and prevents edge cases such as sorting
71  * algorithms that use this function and do not terminate as a
72  * result. */
73  if (!secp256k1_xonly_pubkey_serialize(ctx, out[i], pk[i])) {
74  /* Note that xonly_pubkey_serialize should already set the output to
75  * zero in that case, but it's not guaranteed by the API, we can't
76  * test it and writing a VERIFY_CHECK is more complex than
77  * explicitly memsetting (again). */
78  memset(out[i], 0, sizeof(out[i]));
79  }
80  }
81  return secp256k1_memcmp_var(out[0], out[1], sizeof(out[1]));
82 }
83 
88  int y_parity = 0;
90 
91  if (secp256k1_fe_is_odd(&r->y)) {
92  secp256k1_fe_negate(&r->y, &r->y, 1);
93  y_parity = 1;
94  }
95  return y_parity;
96 }
97 
98 int secp256k1_xonly_pubkey_from_pubkey(const secp256k1_context* ctx, secp256k1_xonly_pubkey *xonly_pubkey, int *pk_parity, const secp256k1_pubkey *pubkey) {
99  secp256k1_ge pk;
100  int tmp;
101 
102  VERIFY_CHECK(ctx != NULL);
103  ARG_CHECK(xonly_pubkey != NULL);
104  ARG_CHECK(pubkey != NULL);
105 
106  if (!secp256k1_pubkey_load(ctx, &pk, pubkey)) {
107  return 0;
108  }
110  if (pk_parity != NULL) {
111  *pk_parity = tmp;
112  }
113  secp256k1_xonly_pubkey_save(xonly_pubkey, &pk);
114  return 1;
115 }
116 
117 int secp256k1_xonly_pubkey_tweak_add(const secp256k1_context* ctx, secp256k1_pubkey *output_pubkey, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
118  secp256k1_ge pk;
119 
120  VERIFY_CHECK(ctx != NULL);
121  ARG_CHECK(output_pubkey != NULL);
122  memset(output_pubkey, 0, sizeof(*output_pubkey));
123  ARG_CHECK(internal_pubkey != NULL);
124  ARG_CHECK(tweak32 != NULL);
125 
126  if (!secp256k1_xonly_pubkey_load(ctx, &pk, internal_pubkey)
127  || !secp256k1_ec_pubkey_tweak_add_helper(&pk, tweak32)) {
128  return 0;
129  }
130  secp256k1_pubkey_save(output_pubkey, &pk);
131  return 1;
132 }
133 
134 int secp256k1_xonly_pubkey_tweak_add_check(const secp256k1_context* ctx, const unsigned char *tweaked_pubkey32, int tweaked_pk_parity, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
135  secp256k1_ge pk;
136  unsigned char pk_expected32[32];
137 
138  VERIFY_CHECK(ctx != NULL);
139  ARG_CHECK(internal_pubkey != NULL);
140  ARG_CHECK(tweaked_pubkey32 != NULL);
141  ARG_CHECK(tweak32 != NULL);
142 
143  if (!secp256k1_xonly_pubkey_load(ctx, &pk, internal_pubkey)
144  || !secp256k1_ec_pubkey_tweak_add_helper(&pk, tweak32)) {
145  return 0;
146  }
149  secp256k1_fe_get_b32(pk_expected32, &pk.x);
150 
151  return secp256k1_memcmp_var(&pk_expected32, tweaked_pubkey32, 32) == 0
152  && secp256k1_fe_is_odd(&pk.y) == tweaked_pk_parity;
153 }
154 
156  secp256k1_scalar_get_b32(&keypair->data[0], sk);
157  secp256k1_pubkey_save((secp256k1_pubkey *)&keypair->data[32], pk);
158 }
159 
160 
162  int ret;
163 
164  ret = secp256k1_scalar_set_b32_seckey(sk, &keypair->data[0]);
165  /* We can declassify ret here because sk is only zero if a keypair function
166  * failed (which zeroes the keypair) and its return value is ignored. */
167  secp256k1_declassify(ctx, &ret, sizeof(ret));
168  ARG_CHECK(ret);
169  return ret;
170 }
171 
172 /* Load a keypair into pk and sk (if non-NULL). This function declassifies pk
173  * and ARG_CHECKs that the keypair is not invalid. It always initializes sk and
174  * pk with dummy values. */
176  int ret;
177  const secp256k1_pubkey *pubkey = (const secp256k1_pubkey *)&keypair->data[32];
178 
179  /* Need to declassify the pubkey because pubkey_load ARG_CHECKs if it's
180  * invalid. */
181  secp256k1_declassify(ctx, pubkey, sizeof(*pubkey));
182  ret = secp256k1_pubkey_load(ctx, pk, pubkey);
183  if (sk != NULL) {
184  ret = ret && secp256k1_keypair_seckey_load(ctx, sk, keypair);
185  }
186  if (!ret) {
187  *pk = secp256k1_ge_const_g;
188  if (sk != NULL) {
189  *sk = secp256k1_scalar_one;
190  }
191  }
192  return ret;
193 }
194 
195 int secp256k1_keypair_create(const secp256k1_context* ctx, secp256k1_keypair *keypair, const unsigned char *seckey32) {
196  secp256k1_scalar sk;
197  secp256k1_ge pk;
198  int ret = 0;
199  VERIFY_CHECK(ctx != NULL);
200  ARG_CHECK(keypair != NULL);
201  memset(keypair, 0, sizeof(*keypair));
203  ARG_CHECK(seckey32 != NULL);
204 
205  ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &sk, &pk, seckey32);
206  secp256k1_keypair_save(keypair, &sk, &pk);
207  secp256k1_memczero(keypair, sizeof(*keypair), !ret);
208 
210  return ret;
211 }
212 
213 int secp256k1_keypair_sec(const secp256k1_context* ctx, unsigned char *seckey, const secp256k1_keypair *keypair) {
214  VERIFY_CHECK(ctx != NULL);
215  ARG_CHECK(seckey != NULL);
216  memset(seckey, 0, 32);
217  ARG_CHECK(keypair != NULL);
218 
219  memcpy(seckey, &keypair->data[0], 32);
220  return 1;
221 }
222 
224  VERIFY_CHECK(ctx != NULL);
225  ARG_CHECK(pubkey != NULL);
226  memset(pubkey, 0, sizeof(*pubkey));
227  ARG_CHECK(keypair != NULL);
228 
229  memcpy(pubkey->data, &keypair->data[32], sizeof(*pubkey));
230  return 1;
231 }
232 
233 int secp256k1_keypair_xonly_pub(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pubkey, int *pk_parity, const secp256k1_keypair *keypair) {
234  secp256k1_ge pk;
235  int tmp;
236 
237  VERIFY_CHECK(ctx != NULL);
238  ARG_CHECK(pubkey != NULL);
239  memset(pubkey, 0, sizeof(*pubkey));
240  ARG_CHECK(keypair != NULL);
241 
242  if (!secp256k1_keypair_load(ctx, NULL, &pk, keypair)) {
243  return 0;
244  }
246  if (pk_parity != NULL) {
247  *pk_parity = tmp;
248  }
249  secp256k1_xonly_pubkey_save(pubkey, &pk);
250 
251  return 1;
252 }
253 
254 int secp256k1_keypair_xonly_tweak_add(const secp256k1_context* ctx, secp256k1_keypair *keypair, const unsigned char *tweak32) {
255  secp256k1_ge pk;
256  secp256k1_scalar sk;
257  int y_parity;
258  int ret;
259 
260  VERIFY_CHECK(ctx != NULL);
261  ARG_CHECK(keypair != NULL);
262  ARG_CHECK(tweak32 != NULL);
263 
264  ret = secp256k1_keypair_load(ctx, &sk, &pk, keypair);
265  memset(keypair, 0, sizeof(*keypair));
266 
267  y_parity = secp256k1_extrakeys_ge_even_y(&pk);
268  if (y_parity == 1) {
269  secp256k1_scalar_negate(&sk, &sk);
270  }
271 
272  ret &= secp256k1_ec_seckey_tweak_add_helper(&sk, tweak32);
273  ret &= secp256k1_ec_pubkey_tweak_add_helper(&pk, tweak32);
274 
275  secp256k1_declassify(ctx, &ret, sizeof(ret));
276  if (ret) {
277  secp256k1_keypair_save(keypair, &sk, &pk);
278  }
279 
281  return ret;
282 }
283 
284 #endif
secp256k1_scalar_negate
static void secp256k1_scalar_negate(secp256k1_scalar *r, const secp256k1_scalar *a)
Compute the complement of a scalar (modulo the group order).
secp256k1_keypair_load
static int secp256k1_keypair_load(const secp256k1_context *ctx, secp256k1_scalar *sk, secp256k1_ge *pk, const secp256k1_keypair *keypair)
Definition: main_impl.h:175
VERIFY_CHECK
#define VERIFY_CHECK(cond)
Definition: util.h:95
secp256k1_ge_is_in_correct_subgroup
static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge *ge)
Determine if a point (which is assumed to be on the curve) is in the correct (sub)group of the curve.
secp256k1_ge::y
secp256k1_fe y
Definition: group.h:19
secp256k1_scalar_get_b32
static void secp256k1_scalar_get_b32(unsigned char *bin, const secp256k1_scalar *a)
Convert a scalar to a byte array.
secp256k1_pubkey_load
static int secp256k1_pubkey_load(const secp256k1_context *ctx, secp256k1_ge *ge, const secp256k1_pubkey *pubkey)
Definition: secp256k1.c:195
secp256k1_context_struct
Definition: secp256k1.c:47
secp256k1_declassify
static SECP256K1_INLINE void secp256k1_declassify(const secp256k1_context *ctx, const void *p, size_t len)
Definition: secp256k1.c:185
secp256k1_fe_normalize_var
static void secp256k1_fe_normalize_var(secp256k1_fe *r)
Normalize a field element, without constant-time guarantee.
secp256k1_fe_set_b32
static int secp256k1_fe_set_b32(secp256k1_fe *r, const unsigned char *a)
Set a field element equal to 32-byte big endian value.
secp256k1_xonly_pubkey_serialize
int secp256k1_xonly_pubkey_serialize(const secp256k1_context *ctx, unsigned char *output32, const secp256k1_xonly_pubkey *pubkey)
Serialize an xonly_pubkey object into a 32-byte sequence.
Definition: main_impl.h:43
secp256k1_memcmp_var
static SECP256K1_INLINE int secp256k1_memcmp_var(const void *s1, const void *s2, size_t n)
Semantics like memcmp.
Definition: util.h:221
ARG_CHECK
#define ARG_CHECK(cond)
Definition: secp256k1.c:34
secp256k1_xonly_pubkey_cmp
int secp256k1_xonly_pubkey_cmp(const secp256k1_context *ctx, const secp256k1_xonly_pubkey *pk0, const secp256k1_xonly_pubkey *pk1)
Compare two x-only public keys using lexicographic order.
Definition: main_impl.h:58
secp256k1_keypair_create
int secp256k1_keypair_create(const secp256k1_context *ctx, secp256k1_keypair *keypair, const unsigned char *seckey32)
Compute the keypair for a secret key.
Definition: main_impl.h:195
secp256k1_xonly_pubkey_parse
int secp256k1_xonly_pubkey_parse(const secp256k1_context *ctx, secp256k1_xonly_pubkey *pubkey, const unsigned char *input32)
Parse a 32-byte sequence into a xonly_pubkey object.
Definition: main_impl.h:21
secp256k1_xonly_pubkey_from_pubkey
int secp256k1_xonly_pubkey_from_pubkey(const secp256k1_context *ctx, secp256k1_xonly_pubkey *xonly_pubkey, int *pk_parity, const secp256k1_pubkey *pubkey)
Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey.
Definition: main_impl.h:98
secp256k1_pubkey_save
static void secp256k1_pubkey_save(secp256k1_pubkey *pubkey, secp256k1_ge *ge)
Definition: secp256k1.c:214
secp256k1_keypair
Opaque data structure that holds a keypair consisting of a secret and a public key.
Definition: secp256k1_extrakeys.h:33
secp256k1_scalar
A scalar modulo the group order of the secp256k1 curve.
Definition: scalar_4x64.h:13
secp256k1_ge_const_g
static const secp256k1_ge secp256k1_ge_const_g
Definition: group_impl.h:62
secp256k1_fe_is_odd
static int secp256k1_fe_is_odd(const secp256k1_fe *a)
Check the "oddness" of a field element.
secp256k1_ecmult_gen_context_is_built
static int secp256k1_ecmult_gen_context_is_built(const secp256k1_ecmult_gen_context *ctx)
Definition: ecmult_gen_impl.h:22
secp256k1_keypair_sec
int secp256k1_keypair_sec(const secp256k1_context *ctx, unsigned char *seckey, const secp256k1_keypair *keypair)
Get the secret key from a keypair.
Definition: main_impl.h:213
secp256k1_fe
Definition: field_10x26.h:12
secp256k1_context_struct::ecmult_gen_ctx
secp256k1_ecmult_gen_context ecmult_gen_ctx
Definition: secp256k1.c:48
secp256k1_keypair_seckey_load
static int secp256k1_keypair_seckey_load(const secp256k1_context *ctx, secp256k1_scalar *sk, const secp256k1_keypair *keypair)
Definition: main_impl.h:161
secp256k1_xonly_pubkey_load
static SECP256K1_INLINE int secp256k1_xonly_pubkey_load(const secp256k1_context *ctx, secp256k1_ge *ge, const secp256k1_xonly_pubkey *pubkey)
Definition: main_impl.h:13
secp256k1_keypair_save
static void secp256k1_keypair_save(secp256k1_keypair *keypair, const secp256k1_scalar *sk, secp256k1_ge *pk)
Definition: main_impl.h:155
secp256k1_fe_get_b32
static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a)
Convert a field element to a 32-byte big endian value.
secp256k1_ec_pubkey_tweak_add_helper
static int secp256k1_ec_pubkey_tweak_add_helper(secp256k1_ge *p, const unsigned char *tweak32)
Definition: secp256k1.c:631
secp256k1_keypair_pub
int secp256k1_keypair_pub(const secp256k1_context *ctx, secp256k1_pubkey *pubkey, const secp256k1_keypair *keypair)
Get the public key from a keypair.
Definition: main_impl.h:223
secp256k1_xonly_pubkey_save
static SECP256K1_INLINE void secp256k1_xonly_pubkey_save(secp256k1_xonly_pubkey *pubkey, secp256k1_ge *ge)
Definition: main_impl.h:17
secp256k1_scalar_one
static const secp256k1_scalar secp256k1_scalar_one
Definition: scalar_impl.h:31
secp256k1_memczero
static SECP256K1_INLINE void secp256k1_memczero(void *s, size_t len, int flag)
Definition: util.h:202
secp256k1_keypair_xonly_pub
int secp256k1_keypair_xonly_pub(const secp256k1_context *ctx, secp256k1_xonly_pubkey *pubkey, int *pk_parity, const secp256k1_keypair *keypair)
Get the x-only public key from a keypair.
Definition: main_impl.h:233
secp256k1_xonly_pubkey_tweak_add_check
int secp256k1_xonly_pubkey_tweak_add_check(const secp256k1_context *ctx, const unsigned char *tweaked_pubkey32, int tweaked_pk_parity, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32)
Checks that a tweaked pubkey is the result of calling secp256k1_xonly_pubkey_tweak_add with internal_...
Definition: main_impl.h:134
secp256k1_scalar_clear
static void secp256k1_scalar_clear(secp256k1_scalar *r)
Clear a scalar to prevent the leak of sensitive data.
secp256k1_extrakeys_ge_even_y
static int secp256k1_extrakeys_ge_even_y(secp256k1_ge *r)
Keeps a group element as is if it has an even Y and otherwise negates it.
Definition: main_impl.h:87
secp256k1_keypair_xonly_tweak_add
int secp256k1_keypair_xonly_tweak_add(const secp256k1_context *ctx, secp256k1_keypair *keypair, const unsigned char *tweak32)
Tweak a keypair by adding tweak32 to the secret key and updating the public key accordingly.
Definition: main_impl.h:254
secp256k1_ge_set_xo_var
static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd)
Set a group element (affine) equal to the point with the given X coordinate, and given oddness for Y.
secp256k1_fe_negate
static void secp256k1_fe_negate(secp256k1_fe *r, const secp256k1_fe *a, int m)
Set a field element equal to the additive inverse of another.
secp256k1_scalar_set_b32_seckey
static int secp256k1_scalar_set_b32_seckey(secp256k1_scalar *r, const unsigned char *bin)
Set a scalar from a big endian byte array and returns 1 if it is a valid seckey and 0 otherwise.
secp256k1_keypair::data
unsigned char data[96]
Definition: secp256k1_extrakeys.h:34
SECP256K1_INLINE
#define SECP256K1_INLINE
Definition: secp256k1.h:127
secp256k1_ge::x
secp256k1_fe x
Definition: group.h:18
secp256k1_ge_is_infinity
static int secp256k1_ge_is_infinity(const secp256k1_ge *a)
Check whether a group element is the point at infinity.
secp256k1_pubkey::data
unsigned char data[64]
Definition: secp256k1.h:71
secp256k1_ec_seckey_tweak_add_helper
static int secp256k1_ec_seckey_tweak_add_helper(secp256k1_scalar *sec, const unsigned char *tweak32)
Definition: secp256k1.c:600
secp256k1_pubkey
Opaque data structure that holds a parsed and valid public key.
Definition: secp256k1.h:70
secp256k1_ge
A group element of the secp256k1 curve, in affine coordinates.
Definition: group.h:13
secp256k1_xonly_pubkey_tweak_add
int secp256k1_xonly_pubkey_tweak_add(const secp256k1_context *ctx, secp256k1_pubkey *output_pubkey, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32)
Tweak an x-only public key by adding the generator multiplied with tweak32 to it.
Definition: main_impl.h:117
ctx
static secp256k1_context * ctx
Definition: tests.c:32
secp256k1_xonly_pubkey
Opaque data structure that holds a parsed and valid "x-only" public key.
Definition: secp256k1_extrakeys.h:22
secp256k1_ec_pubkey_create_helper
static int secp256k1_ec_pubkey_create_helper(const secp256k1_ecmult_gen_context *ecmult_gen_ctx, secp256k1_scalar *seckey_scalar, secp256k1_ge *p, const unsigned char *seckey)
Definition: secp256k1.c:535