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fixup! feat(crypto): implement elligator2

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This commit is contained in:
Ondřej Vejpustek 2023-12-05 15:15:17 +01:00
parent 9acdaed06b
commit a412a857f1
1 changed files with 4 additions and 25 deletions
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29
crypto/elligator2.c
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@ -161,30 +161,24 @@ bool map_to_curve_elligator2_curve25519(const bignum25519 input,
bignum25519 y22 = {0};
curve25519_mul(y22, y21, c3);
memzero(c3, sizeof(c3));
memzero(y22, sizeof(y22));
// gx2 = gx1 * tv1
bignum25519 gx2 = {0};
curve25519_mul(gx2, gx1, tv1);
memzero(gx2, sizeof(gx2));
memzero(tv1, sizeof(tv1));
// tv2 = y21^2
curve25519_square(tv2, y21);
memzero(y21, sizeof(y21));
// tv2 = tv2 * gxd
curve25519_mul(tv2, tv2, gxd);
// e2 = tv2 == gx2
// int e2 = curve25519_isequal(tv2, gx2);
memzero(gx2, sizeof(gx2));
// y2 = CMOV(y22, y21, e2)
// bignum25519 y2 = {0};
// curve25519_cmov(y2, y22, y21, e2);
memzero(y21, sizeof(y21));
memzero(y22, sizeof(y22));
// tv2 = y1^2
curve25519_square(tv2, y1);
memzero(y1, sizeof(y1));
// tv2 = tv2 * gxd
curve25519_mul(tv2, tv2, gxd);
@ -201,21 +195,6 @@ bool map_to_curve_elligator2_curve25519(const bignum25519 input,
memzero(x1n, sizeof(x1n));
memzero(x2n, sizeof(x2n));
// y = CMOV(y2, y1, e3)
// bignum25519 y = {0};
// curve25519_cmov(y, y2, y1, e3);
memzero(y1, sizeof(y1));
// memzero(y2, sizeof(y2));
// e4 = sgn0(y) == 1
// int e4 = curve25519_isnegative(y);
// y = CMOV(y, -y, e3 XOR e4)
// bignum25519 minus_y = {0};
// curve25519_neg(minus_y, y);
// curve25519_cmov(y, minus_y, y, e3 ^ e4);
// memzero(minus_y, sizeof(minus_y));
// x = xn / xd
bignum25519 x = {0};
curve25519_recip(x, xd);