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internal/ed25519: rearrange VartimeDoubleBaseMul args 

This way they line up with a*A + b*B (except B is implicit).
This commit is contained in:
Henry de Valence 2019-05-09 00:20:01 -07:00 committed by Filippo Valsorda
parent 1e66180e96
commit 2d09ffd636
2 changed files with 5 additions and 5 deletions
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2
internal/edwards25519/scalarMul.go
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@ -157,7 +157,7 @@ func (v *ProjP3) MultiscalarMul(scalars []scalar.Scalar, points []*ProjP3) *Proj
// Set v to a*A + b*B, where B is the Ed25519 basepoint, and return v.
//
// The scalar multiplication is done in variable time.
func (v *ProjP3) VartimeDoubleBaseMul(a, b *scalar.Scalar, A *ProjP3) *ProjP3 {
func (v *ProjP3) VartimeDoubleBaseMul(a *scalar.Scalar, A *ProjP3, b *scalar.Scalar) *ProjP3 {
// Similarly to the single variable-base approach, we compute
// digits and use them with a lookup table. However, because
// we are allowed to do variable-time operations, we don't

8
internal/edwards25519/scalarMul_test.go
View File

@ -59,11 +59,11 @@ func TestBasepointMulVsDalek(t *testing.T) {
func TestVartimeDoubleBaseMulVsDalek(t *testing.T) {
var p ProjP3
var z scalar.Scalar
p.VartimeDoubleBaseMul(&dalekScalar, &z, &B)
p.VartimeDoubleBaseMul(&dalekScalar, &B, &z)
if dalekScalarBasepoint.Equal(&p) != 1 {
t.Error("VartimeDoubleBaseMul fails with b=0")
}
p.VartimeDoubleBaseMul(&z, &dalekScalar, &B)
p.VartimeDoubleBaseMul(&z, &B, &dalekScalar)
if dalekScalarBasepoint.Equal(&p) != 1 {
t.Error("VartimeDoubleBaseMul fails with a=0")
}
@ -175,7 +175,7 @@ func TestVartimeDoubleBaseMulMatchesBasepointMul(t *testing.T) {
y[31] &= 127
var p, q1, q2, check ProjP3
p.VartimeDoubleBaseMul(&x, &y, &B)
p.VartimeDoubleBaseMul(&x, &B, &y)
q1.BasepointMul(&x)
q2.BasepointMul(&y)
@ -236,7 +236,7 @@ func BenchmarkVartimeDoubleBaseMul(t *testing.B) {
var p ProjP3
for i := 0; i < t.N; i++ {
p.VartimeDoubleBaseMul(&dalekScalar, &dalekScalar, &B)
p.VartimeDoubleBaseMul(&dalekScalar, &B, &dalekScalar)
}
}