diff options
Diffstat (limited to 'src/lib/pubkey/ec_group/point_mul.cpp')
| -rw-r--r-- | src/lib/pubkey/ec_group/point_mul.cpp | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/src/lib/pubkey/ec_group/point_mul.cpp b/src/lib/pubkey/ec_group/point_mul.cpp index d42a5d5e8..d052b837c 100644 --- a/src/lib/pubkey/ec_group/point_mul.cpp +++ b/src/lib/pubkey/ec_group/point_mul.cpp @@ -6,6 +6,7 @@ #include <botan/internal/point_mul.h> #include <botan/rng.h> +#include <botan/reducer.h> #include <botan/internal/rounding.h> namespace Botan { @@ -38,8 +39,10 @@ PointGFp Blinded_Point_Multiply::blinded_multiply(const BigInt& scalar, return m_point_mul->mul(scalar, rng, m_order, m_ws); } -PointGFp_Base_Point_Precompute::PointGFp_Base_Point_Precompute(const PointGFp& base) : +PointGFp_Base_Point_Precompute::PointGFp_Base_Point_Precompute(const PointGFp& base, + const Modular_Reducer& mod_order) : m_base_point(base), + m_mod_order(mod_order), m_p_words(base.get_curve().get_p().size()), m_T_size(base.get_curve().get_p().bits() + PointGFp_SCALAR_BLINDING_BITS + 1) { @@ -97,7 +100,9 @@ PointGFp PointGFp_Base_Point_Precompute::mul(const BigInt& k, // Choose a small mask m and use k' = k + m*order (Coron's 1st countermeasure) const BigInt mask(rng, PointGFp_SCALAR_BLINDING_BITS, false); - const BigInt scalar = k + group_order * mask; + + // Instead of reducing k mod group order should we alter the mask size?? + const BigInt scalar = m_mod_order.reduce(k) + group_order * mask; size_t windows = round_up(scalar.bits(), 2) / 2; |