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authorlloyd <lloyd@randombit.net>2010-03-13 05:47:14 +0000
committerlloyd <lloyd@randombit.net>2010-03-13 05:47:14 +0000
commitb6851ef0eecf0910e310d27da6afe3bd926bfc8a (patch)
tree626653a0263979e14e6fd955e8349bab4827471b /src/math
parent1d0538d6906f3f0695976da3fde65eb72e830afb (diff)
Small monty_mult cleanup
Diffstat (limited to 'src/math')
-rw-r--r--src/math/numbertheory/point_gfp.cpp18
1 files changed, 8 insertions, 10 deletions
diff --git a/src/math/numbertheory/point_gfp.cpp b/src/math/numbertheory/point_gfp.cpp
index 93714e219..25b267822 100644
--- a/src/math/numbertheory/point_gfp.cpp
+++ b/src/math/numbertheory/point_gfp.cpp
@@ -35,22 +35,21 @@ PointGFp::PointGFp(const CurveGFp& curve, const BigInt& x, const BigInt& y) :
BigInt PointGFp::monty_mult(const BigInt& a, const BigInt& b)
{
- BigInt result = 0;
-
if(a.is_zero() || b.is_zero())
- return result;
+ return 0;
const BigInt& p = curve.get_p();
const u32bit p_size = p.sig_words();
const word p_dash = curve.get_p_dash();
- result.grow_to(p_size);
+ BigInt result;
+ result.grow_to(2*p_size+1);
SecureVector<word> t;
t.grow_to(2*p_size+1);
- if(a > 0 && b > 0 && a < p && b < p && a.size() >= p_size && b.size() >= p_size)
+ if(a > 0 && b > 0 && a < p && b < p)
{
bigint_simple_mul(t, a.data(), a.sig_words(), b.data(), b.sig_words());
}
@@ -58,18 +57,17 @@ BigInt PointGFp::monty_mult(const BigInt& a, const BigInt& b)
{
const Modular_Reducer& mod_p = curve.mod_p();
- BigInt a2 = a;
- BigInt b2 = b;
+ BigInt a2 = mod_p.reduce(a);
+ BigInt b2 = mod_p.reduce(b);
+
a2.grow_to(p_size);
b2.grow_to(p_size);
- a2 = mod_p.reduce(a2);
- b2 = mod_p.reduce(b2);
-
bigint_simple_mul(t, a2.data(), a2.sig_words(), b2.data(), b2.sig_words());
}
bigint_monty_redc(&t[0], t.size(), p.data(), p_size, p_dash);
+
copy_mem(&result[0], &t[p_size], p_size);
return result;