diff options
Diffstat (limited to 'src/lib')
| -rw-r--r-- | src/lib/math/ec_gfp/point_gfp.cpp | 50 |
1 files changed, 2 insertions, 48 deletions
diff --git a/src/lib/math/ec_gfp/point_gfp.cpp b/src/lib/math/ec_gfp/point_gfp.cpp index bb446566e..5283b7352 100644 --- a/src/lib/math/ec_gfp/point_gfp.cpp +++ b/src/lib/math/ec_gfp/point_gfp.cpp @@ -314,8 +314,6 @@ Blinded_Point_Multiply::Blinded_Point_Multiply(const PointGFp& base, const BigIn const CurveGFp& curve = base.get_curve(); -#if BOTAN_POINTGFP_BLINDED_MULTIPLY_USE_MONTGOMERY_LADDER - const PointGFp inv = -base; m_U.resize(6*m_h + 3); @@ -332,17 +330,6 @@ Blinded_Point_Multiply::Blinded_Point_Multiply(const PointGFp& base, const BigIn m_U[3*m_h+1-i] = m_U[3*m_h+2-i]; m_U[3*m_h+1-i].add(inv, m_ws); } -#else - m_U.resize(1 << m_h); - m_U[0] = PointGFp::zero_of(curve); - m_U[1] = base; - - for(size_t i = 2; i < m_U.size(); ++i) - { - m_U[i] = m_U[i-1]; - m_U[i].add(base, m_ws); - } -#endif } PointGFp Blinded_Point_Multiply::blinded_multiply(const BigInt& scalar_in, @@ -351,9 +338,9 @@ PointGFp Blinded_Point_Multiply::blinded_multiply(const BigInt& scalar_in, if(scalar_in.is_negative()) throw Invalid_Argument("Blinded_Point_Multiply scalar must be positive"); -#if BOTAN_POINTGFP_SCALAR_BLINDING_BITS > 0 +#if BOTAN_POINTGFP_USE_SCALAR_BLINDING // Choose a small mask m and use k' = k + m*order (Coron's 1st countermeasure) - const BigInt mask(rng, BOTAN_POINTGFP_SCALAR_BLINDING_BITS, false); + const BigInt mask(rng, (m_order.bits()+1)/2, false); const BigInt scalar = scalar_in + m_order * mask; #else const BigInt& scalar = scalar_in; @@ -365,7 +352,6 @@ PointGFp Blinded_Point_Multiply::blinded_multiply(const BigInt& scalar_in, for(size_t i = 0; i != m_U.size(); ++i) m_U[i].randomize_repr(rng); -#if BOTAN_POINTGFP_BLINDED_MULTIPLY_USE_MONTGOMERY_LADDER PointGFp R = m_U.at(3*m_h + 2); // base point int32_t alpha = 0; @@ -395,38 +381,6 @@ PointGFp Blinded_Point_Multiply::blinded_multiply(const BigInt& scalar_in, const int32_t k0 = scalar.get_bit(0); R.add(m_U[3*m_h + 1 - alpha - (k0 ^ 1)], m_ws); -#else - - // N-bit windowing exponentiation: - - size_t windows = round_up(scalar_bits, m_h) / m_h; - - PointGFp R = m_U[0]; - - if(windows > 0) - { - windows--; - const uint32_t nibble = scalar.get_substring(windows*m_h, m_h); - R.add(m_U[nibble], m_ws); - - /* - Randomize after adding the first nibble as before the addition R - is zero, and we cannot effectively randomize the point - representation of the zero point. - */ - R.randomize_repr(rng); - - while(windows) - { - for(size_t i = 0; i != m_h; ++i) - R.mult2(m_ws); - - const uint32_t inner_nibble = scalar.get_substring((windows-1)*m_h, m_h); - R.add(m_U[inner_nibble], m_ws); - windows--; - } - } -#endif //BOTAN_ASSERT(R.on_the_curve(), "Output is on the curve"); |