frost/secp256k1-zkp
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Eliminate the prej array from ecmult_strauss_wnaf.

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Russell O'Connor
2021-02-26 15:18:50 -05:00
parent c9da1baad1
commit e5c18892db
4 changed files with 80 additions and 49 deletions
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33
src/group.h
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@@ -9,7 +9,10 @@
#include "field.h"
/** A group element of the secp256k1 curve, in affine coordinates. */
/** A group element in affine coordinates on the secp256k1 curve,
* or occasionally on an isomorphic curve of the form y^2 = x^3 + 7*t^6.
* Note: For exhaustive test mode, secp256k1 is replaced by a small subgroup of a different curve.
*/
typedef struct {
secp256k1_fe x;
secp256k1_fe y;
@@ -19,7 +22,9 @@ typedef struct {
#define SECP256K1_GE_CONST(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) {SECP256K1_FE_CONST((a),(b),(c),(d),(e),(f),(g),(h)), SECP256K1_FE_CONST((i),(j),(k),(l),(m),(n),(o),(p)), 0}
#define SECP256K1_GE_CONST_INFINITY {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), 1}
/** A group element of the secp256k1 curve, in jacobian coordinates. */
/** A group element of the secp256k1 curve, in jacobian coordinates.
* Note: For exhastive test mode, sepc256k1 is replaced by a small subgroup of a different curve.
*/
typedef struct {
secp256k1_fe x; /* actual X: x/z^2 */
secp256k1_fe y; /* actual Y: y/z^3 */
@@ -64,12 +69,24 @@ static void secp256k1_ge_set_gej_var(secp256k1_ge *r, secp256k1_gej *a);
/** Set a batch of group elements equal to the inputs given in jacobian coordinates */
static void secp256k1_ge_set_all_gej_var(secp256k1_ge *r, const secp256k1_gej *a, size_t len);
/** Bring a batch inputs given in jacobian coordinates (with known z-ratios) to
* the same global z "denominator". zr must contain the known z-ratios such
* that mul(a[i].z, zr[i+1]) == a[i+1].z. zr[0] is ignored. The x and y
* coordinates of the result are stored in r, the common z coordinate is
* stored in globalz. */
static void secp256k1_ge_globalz_set_table_gej(size_t len, secp256k1_ge *r, secp256k1_fe *globalz, const secp256k1_gej *a, const secp256k1_fe *zr);
/** Bring a batch of inputs to the same global z "denominator", based on ratios between
* (omitted) z coordinates of adjacent elements.
*
* Although the elements a[i] are _ge rather than _gej, they actually represent elements
* in Jacobian coordinates with their z coordinates omitted.
*
* Using the notation z(b) to represent the omitted z coordinate of b, the array zr of
* z coordinate ratios must satisfy zr[i] == z(a[i]) / z(a[i-1]) for 0 < 'i' < len.
* The zr[0] value is unused.
*
* This function adjusts the coordinates of 'a' in place so that for all 'i', z(a[i]) == z(a[len-1]).
* In other words, the initial value of z(a[len-1]) becomes the global z "denominator". Only the
* a[i].x and a[i].y coordinates are explicitly modified; the adjustment of the omitted z coordinate is
* implicit.
*
* The coordinates of the final element a[len-1] are not changed.
*/
static void secp256k1_ge_table_set_globalz(size_t len, secp256k1_ge *a, const secp256k1_fe *zr);
/** Set a group element (affine) equal to the point at infinity. */
static void secp256k1_ge_set_infinity(secp256k1_ge *r);