diff options
| -rw-r--r-- | src/math/numbertheory/point_gfp.cpp | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/src/math/numbertheory/point_gfp.cpp b/src/math/numbertheory/point_gfp.cpp index 723fb473b..ed9c0acc8 100644 --- a/src/math/numbertheory/point_gfp.cpp +++ b/src/math/numbertheory/point_gfp.cpp @@ -57,9 +57,6 @@ BigInt PointGFp::monty_mult(const BigInt& a, const BigInt& b) BigInt a2 = mod_p.reduce(a); BigInt b2 = mod_p.reduce(b); - a2.grow_to(p_size); - b2.grow_to(p_size); - bigint_simple_mul(t, a2.data(), a2.sig_words(), b2.data(), b2.sig_words()); } @@ -117,9 +114,14 @@ PointGFp& PointGFp::operator+=(const PointGFp& rhs) BigInt x = mod_p.reduce(monty_mult(r, r) - S2 - U2*2); - U2 = mod_p.reduce(U2 - x); + U2 -= x; + if(U2.is_negative()) + U2 += curve.get_p(); BigInt y = monty_mult(r, U2) - monty_mult(S1, S2); + if(y.is_negative()) + y += curve.get_p(); + BigInt z = monty_mult(monty_mult(coord_z, rhs.coord_z), H); coord_x = x; @@ -225,13 +227,18 @@ void PointGFp::mult2() BigInt M = mod_p.reduce(a_z4 + 3 * monty_mult(coord_x, coord_x)); - BigInt x = monty_mult(M, M) - 2*S; + BigInt x = mod_p.reduce(monty_mult(M, M) - 2*S); - BigInt U = 8 * monty_mult(y_2, y_2); + BigInt U = mod_p.reduce(monty_mult(y_2, y_2) << 3); BigInt y = monty_mult(M, S - x) - U; + if(y.is_negative()) + y += curve.get_p(); + BigInt z = 2 * monty_mult(coord_y, coord_z); + if(z >= curve.get_p()) + z -= curve.get_p(); coord_x = x; coord_y = y; |