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// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build amd64 || arm64
package elliptic
import (
"crypto/internal/nistec"
"math/big"
)
func (c p256Curve) Inverse(k *big.Int) *big.Int {
if k.Sign() < 0 {
// This should never happen.
k = new(big.Int).Neg(k)
}
if k.Cmp(c.params.N) >= 0 {
// This should never happen.
k = new(big.Int).Mod(k, c.params.N)
}
scalar := k.FillBytes(make([]byte, 32))
inverse, err := nistec.P256OrdInverse(scalar)
if err != nil {
panic("crypto/elliptic: nistec rejected normalized scalar")
}
return new(big.Int).SetBytes(inverse)
}
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