Make pubkeys, set_xo, ... ge instead of gej
[secp256k1.git] / src / group.h
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1#ifndef _SECP256K1_GROUP_
2#define _SECP256K1_GROUP_
3
607884fc 4#include "num.h"
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5#include "field.h"
6
7fef6619 7/** A group element of the secp256k1 curve, in affine coordinates. */
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8typedef struct {
9 secp256k1_fe_t x;
10 secp256k1_fe_t y;
7fef6619 11 int infinity; // whether this represents the point at infinity
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12} secp256k1_ge_t;
13
7fef6619 14/** A group element of the secp256k1 curve, in jacobian coordinates. */
254327e4 15typedef struct {
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16 secp256k1_fe_t x; // actual X: x/z^2
17 secp256k1_fe_t y; // actual Y: y/z^3
254327e4 18 secp256k1_fe_t z;
7fef6619 19 int infinity; // whether this represents the point at infinity
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20} secp256k1_gej_t;
21
7fef6619 22/** Global constants related to the group */
254327e4 23typedef struct {
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24 secp256k1_num_t order; // the order of the curve (= order of its generator)
25 secp256k1_ge_t g; // the generator point
26
27 // constants related to secp256k1's efficiently computable endomorphism
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28 secp256k1_fe_t beta;
29 secp256k1_num_t lambda, a1b2, b1, a2;
30} secp256k1_ge_consts_t;
31
f491cd35 32static const secp256k1_ge_consts_t *secp256k1_ge_consts = NULL;
254327e4 33
7fef6619 34/** Initialize the group module. */
254327e4 35void static secp256k1_ge_start(void);
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36
37/** De-initialize the group module. */
254327e4 38void static secp256k1_ge_stop(void);
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39
40/** Set a group element equal to the point at infinity */
254327e4 41void static secp256k1_ge_set_infinity(secp256k1_ge_t *r);
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42
43/** Set a group element equal to the point with given X and Y coordinates */
254327e4 44void static secp256k1_ge_set_xy(secp256k1_ge_t *r, const secp256k1_fe_t *x, const secp256k1_fe_t *y);
7fef6619 45
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46/** Set a group element (jacobian) equal to the point with given X coordinate, and given oddness for Y.
47 The result is not guaranteed to be valid. */
48void static secp256k1_ge_set_xo(secp256k1_ge_t *r, const secp256k1_fe_t *x, int odd);
49
7fef6619 50/** Check whether a group element is the point at infinity. */
254327e4 51int static secp256k1_ge_is_infinity(const secp256k1_ge_t *a);
7fef6619 52
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53/** Check whether a group element is valid (i.e., on the curve). */
54int static secp256k1_ge_is_valid(const secp256k1_ge_t *a);
55
254327e4 56void static secp256k1_ge_neg(secp256k1_ge_t *r, const secp256k1_ge_t *a);
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57
58/** Get a hex representation of a point. *rlen will be overwritten with the real length. */
254327e4 59void static secp256k1_ge_get_hex(char *r, int *rlen, const secp256k1_ge_t *a);
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60
61/** Set a group element equal to another which is given in jacobian coordinates */
f11ff5be 62void static secp256k1_ge_set_gej(secp256k1_ge_t *r, secp256k1_gej_t *a);
254327e4 63
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64
65/** Set a group element (jacobian) equal to the point at infinity. */
254327e4 66void static secp256k1_gej_set_infinity(secp256k1_gej_t *r);
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67
68/** Set a group element (jacobian) equal to the point with given X and Y coordinates. */
254327e4 69void static secp256k1_gej_set_xy(secp256k1_gej_t *r, const secp256k1_fe_t *x, const secp256k1_fe_t *y);
7fef6619 70
7fef6619 71/** Set a group element (jacobian) equal to another which is given in affine coordinates. */
254327e4 72void static secp256k1_gej_set_ge(secp256k1_gej_t *r, const secp256k1_ge_t *a);
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73
74/** Get the X coordinate of a group element (jacobian). */
254327e4 75void static secp256k1_gej_get_x(secp256k1_fe_t *r, const secp256k1_gej_t *a);
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76
77/** Set r equal to the inverse of a (i.e., mirrored around the X axis) */
254327e4 78void static secp256k1_gej_neg(secp256k1_gej_t *r, const secp256k1_gej_t *a);
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79
80/** Check whether a group element is the point at infinity. */
254327e4 81int static secp256k1_gej_is_infinity(const secp256k1_gej_t *a);
7fef6619 82
7fef6619 83/** Set r equal to the double of a. */
254327e4 84void static secp256k1_gej_double(secp256k1_gej_t *r, const secp256k1_gej_t *a);
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85
86/** Set r equal to the sum of a and b. */
254327e4 87void static secp256k1_gej_add(secp256k1_gej_t *r, const secp256k1_gej_t *a, const secp256k1_gej_t *b);
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88
89/** Set r equal to the sum of a and b (with b given in jacobian coordinates). This is more efficient
90 than secp256k1_gej_add. */
254327e4 91void static secp256k1_gej_add_ge(secp256k1_gej_t *r, const secp256k1_gej_t *a, const secp256k1_ge_t *b);
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92
93/** Get a hex representation of a point. *rlen will be overwritten with the real length. */
254327e4 94void static secp256k1_gej_get_hex(char *r, int *rlen, const secp256k1_gej_t *a);
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95
96/** Set r to be equal to lambda times a, where lambda is chosen in a way such that this is very fast. */
254327e4 97void static secp256k1_gej_mul_lambda(secp256k1_gej_t *r, const secp256k1_gej_t *a);
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98
99/** Find r1 and r2 such that r1+r2*lambda = a, and r1 and r2 are maximum 128 bits long (given that a is
100 not more than 256 bits). */
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101void static secp256k1_gej_split_exp(secp256k1_num_t *r1, secp256k1_num_t *r2, const secp256k1_num_t *a);
102
b394396b 103#endif
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