public static void select(Ge_cached t, Ge_cached[] pre, byte b)
{
Ge_cached minust = new Ge_cached();
int bnegative = negative((sbyte)b);
int babs = b - (((-bnegative) & b) << 1);
Fe_1.fe_1(t.YplusX);
Fe_1.fe_1(t.YminusX);
Fe_1.fe_1(t.Z);
Fe_1.fe_1(t.Z);
Fe_0.fe_0(t.T2d);
cmov(t, pre[0], equal((byte)babs, 1));
cmov(t, pre[1], equal((byte)babs, 2));
cmov(t, pre[2], equal((byte)babs, 3));
cmov(t, pre[3], equal((byte)babs, 4));
cmov(t, pre[4], equal((byte)babs, 5));
cmov(t, pre[5], equal((byte)babs, 6));
cmov(t, pre[6], equal((byte)babs, 7));
cmov(t, pre[7], equal((byte)babs, 8));
Fe_copy.fe_copy(minust.YplusX, t.YminusX);
Fe_copy.fe_copy(minust.YminusX, t.YplusX);
Fe_copy.fe_copy(minust.Z, t.Z);
Fe_neg.fe_neg(minust.T2d, t.T2d);
cmov(t, minust, bnegative);
}
public static void ge_montx_to_p2(Ge_p2 p, int[] u, byte ed_sign_bit)
{
int[] x = new int[10];
int[] y = new int[10];
int[] A = new int[10];
int[] v = new int[10];
int[] v2 = new int[10];
int[] iv = new int[10];
int[] nx = new int[10];
Fe_frombytes.fe_frombytes(A, A_bytes);
/* given u, recover edwards y */
/* given u, recover v */
/* given u and v, recover edwards x */
Fe_montx_to_edy.fe_montx_to_edy(y, u); /* y = (u - 1) / (u + 1) */
Fe_mont_rhs.fe_mont_rhs(v2, u); /* v^2 = u(u^2 + Au + 1) */
Fe_sqrt.fe_sqrt(v, v2); /* v = sqrt(v^2) */
Fe_mul.fe_mul(x, u, A); /* x = u * sqrt(-(A+2)) */
Fe_invert.fe_invert(iv, v); /* 1/v */
Fe_mul.fe_mul(x, x, iv); /* x = (u/v) * sqrt(-(A+2)) */
Fe_neg.fe_neg(nx, x); /* negate x to match sign bit */
Fe_cmov.fe_cmov(x, nx, Fe_isnegative.fe_isnegative(x) ^ ed_sign_bit);
Fe_copy.fe_copy(p.X, x);
Fe_copy.fe_copy(p.Y, y);
Fe_1.fe_1(p.Z);
/* POSTCONDITION: check that p->X and p->Y satisfy the Ed curve equation */
/* -x^2 + y^2 = 1 + dx^2y^2 */
//#ifndef NDEBUG
//{
//fe one, d, x2, y2, x2y2, dx2y2;
//
//unsigned char dbytes[32] = {
//0xa3, 0x78, 0x59, 0x13, 0xca, 0x4d, 0xeb, 0x75,
//0xab, 0xd8, 0x41, 0x41, 0x4d, 0x0a, 0x70, 0x00,
//0x98, 0xe8, 0x79, 0x77, 0x79, 0x40, 0xc7, 0x8c,
//0x73, 0xfe, 0x6f, 0x2b, 0xee, 0x6c, 0x03, 0x52
//};
//
//fe_frombytes(d, dbytes);
//fe_1(one);
//fe_sq(x2, p->X); /* x^2 */
//fe_sq(y2, p->Y); /* y^2 */
//
//fe_mul(dx2y2, x2, y2); /* x^2y^2 */
//fe_mul(dx2y2, dx2y2, d); /* dx^2y^2 */
//fe_add(dx2y2, dx2y2, one); /* dx^2y^2 + 1 */
//fe_neg(x2y2, x2); /* -x^2 */
//fe_add(x2y2, x2y2, y2); /* -x^2 + y^2 */
//
//assert(fe_isequal(x2y2, dx2y2));
//}
//#endif
}
/*
* return r = -p
*/
public static void ge_neg(Ge_p3 r, Ge_p3 p)
{
Fe_neg.fe_neg(r.X, p.X);
Fe_copy.fe_copy(r.Y, p.Y);
Fe_copy.fe_copy(r.Z, p.Z);
Fe_neg.fe_neg(r.T, p.T);
}
public static int ge_frombytes_negate_vartime(Ge_p3 h, byte[] s)
{
int[] u = new int[10];
int[] v = new int[10];
int[] v3 = new int[10];
int[] vxx = new int[10];
int[] check = new int[10];
Fe_frombytes.fe_frombytes(h.Y, s);
Fe_1.fe_1(h.Z);
Fe_sq.fe_sq(u, h.Y);
Fe_mul.fe_mul(v, u, d);
Fe_sub.fe_sub(u, u, h.Z); /* u = y^2-1 */
Fe_add.fe_add(v, v, h.Z); /* v = dy^2+1 */
Fe_sq.fe_sq(v3, v);
Fe_mul.fe_mul(v3, v3, v); /* v3 = v^3 */
Fe_sq.fe_sq(h.X, v3);
Fe_mul.fe_mul(h.X, h.X, v);
Fe_mul.fe_mul(h.X, h.X, u); /* x = uv^7 */
Fe_pow22523.fe_pow22523(h.X, h.X); /* x = (uv^7)^((q-5)/8) */
Fe_mul.fe_mul(h.X, h.X, v3);
Fe_mul.fe_mul(h.X, h.X, u); /* x = uv^3(uv^7)^((q-5)/8) */
Fe_sq.fe_sq(vxx, h.X);
Fe_mul.fe_mul(vxx, vxx, v);
Fe_sub.fe_sub(check, vxx, u); /* vx^2-u */
if (Fe_isnonzero.fe_isnonzero(check) != 0)
{
Fe_add.fe_add(check, vxx, u); /* vx^2+u */
if (Fe_isnonzero.fe_isnonzero(check) != 0)
{
return(-1);
}
Fe_mul.fe_mul(h.X, h.X, sqrtm1);
}
if (Fe_isnegative.fe_isnegative(h.X) == ((((uint)s[31]) >> 7) & 0x01))
{
Fe_neg.fe_neg(h.X, h.X);
}
Fe_mul.fe_mul(h.T, h.X, h.Y);
return(0);
}
static void select(Ge_precomp t, int pos, byte b)
{
Ge_precomp[,] gepc_base = (pos <= 7 ? Ge_precomp_base_0_7.gepc_base :
(pos <= 15 ? Ge_precomp_base_8_15.gepc_base :
(pos <= 23 ? Ge_precomp_base_16_23.gepc_base : Ge_precomp_base_24_31.gepc_base)));
Ge_precomp minust = new Ge_precomp();
int bnegative = negative((sbyte)b);
int babs = b - (((-bnegative) & b) << 1);
Ge_precomp_0.ge_precomp_0(t);
cmov(t, gepc_base[pos, 0], equal((byte)babs, (byte)1));
cmov(t, gepc_base[pos, 1], equal((byte)babs, (byte)2));
cmov(t, gepc_base[pos, 2], equal((byte)babs, (byte)3));
cmov(t, gepc_base[pos, 3], equal((byte)babs, (byte)4));
cmov(t, gepc_base[pos, 4], equal((byte)babs, (byte)5));
cmov(t, gepc_base[pos, 5], equal((byte)babs, (byte)6));
cmov(t, gepc_base[pos, 6], equal((byte)babs, (byte)7));
cmov(t, gepc_base[pos, 7], equal((byte)babs, (byte)8));
Fe_copy.fe_copy(minust.yplusx, t.yminusx);
Fe_copy.fe_copy(minust.yminusx, t.yplusx);
Fe_neg.fe_neg(minust.xy2d, t.xy2d);
cmov(t, minust, bnegative);
}
