P2Pool/edwards25519
P2Pool/edwards25519
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field: fix heap escape in SqrtRatio

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We were reusing a named return as a function variable name, which was
causing it to escape to the heap, and cause an allocation in Ed25519
verification.
This commit is contained in:
Filippo Valsorda 2022-01-05 09:33:10 -05:00
parent 18ef51f6b0
commit 17a0e597a6
1 changed files with 2 additions and 2 deletions
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4
field/fe.go
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@ -395,14 +395,14 @@ var sqrtM1 = &Element{1718705420411056, 234908883556509,
// If u/v is square, SqrtRatio returns r and 1. If u/v is not square, SqrtRatio
// sets r according to Section 4.3 of draft-irtf-cfrg-ristretto255-decaf448-00,
// and returns r and 0.
func (r *Element) SqrtRatio(u, v *Element) (rr *Element, wasSquare int) {
func (r *Element) SqrtRatio(u, v *Element) (R *Element, wasSquare int) {
t0 := new(Element)
// r = (u * v3) * (u * v7)^((p-5)/8)
v2 := new(Element).Square(v)
uv3 := new(Element).Multiply(u, t0.Multiply(v2, v))
uv7 := new(Element).Multiply(uv3, t0.Square(v2))
rr = new(Element).Multiply(uv3, t0.Pow22523(uv7))
rr := new(Element).Multiply(uv3, t0.Pow22523(uv7))
check := new(Element).Multiply(v, t0.Square(rr)) // check = v * r^2