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29 lines
720 B
Go
29 lines
720 B
Go
//go:build (amd64 && !generic) || (arm64 && !generic)
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// +build amd64,!generic arm64,!generic
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package sm2ec
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import (
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"math/big"
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_sm2ec "github.com/emmansun/gmsm/internal/sm2ec"
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)
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// Inverse, implements invertible interface, used by Sign()
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func (curve *sm2Curve) Inverse(k *big.Int) *big.Int {
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if k.Sign() < 0 {
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// This should never happen.
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k = new(big.Int).Neg(k)
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}
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if k.Cmp(curve.params.N) >= 0 {
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// This should never happen.
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k = new(big.Int).Mod(k, curve.params.N)
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}
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scalar := k.FillBytes(make([]byte, 32))
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inverse, err := _sm2ec.P256OrdInverse(scalar)
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if err != nil {
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panic("sm2/elliptic: sm2 rejected normalized scalar")
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}
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return new(big.Int).SetBytes(inverse)
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}
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