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53 lines
1.3 KiB
Go
53 lines
1.3 KiB
Go
//go:build purego || !(amd64 || arm64 || s390x || ppc64le)
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package sm2ec
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import (
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"errors"
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"github.com/emmansun/gmsm/internal/sm2ec/fiat"
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)
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// P256OrdInverse, sets out to in⁻¹ mod org(G). If in is zero, out will be zero.
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// n-2 =
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// 1111111111111111111111111111111011111111111111111111111111111111
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// 1111111111111111111111111111111111111111111111111111111111111111
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// 0111001000000011110111110110101100100001110001100000010100101011
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// 0101001110111011111101000000100100111001110101010100000100100001
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//
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func P256OrdInverse(k []byte) ([]byte, error) {
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if len(k) != 32 {
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return nil, errors.New("invalid scalar length")
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}
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x := new(fiat.SM2P256OrderElement)
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_, err := x.SetBytes(k)
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if err != nil {
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return nil, err
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}
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xinv := new(fiat.SM2P256OrderElement).Invert(x)
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return xinv.Bytes(), nil
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}
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// P256OrdMul multiplication modulo org(G).
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func P256OrdMul(in1, in2 []byte) ([]byte, error) {
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if len(in1) != 32 || len(in2) != 32 {
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return nil, errors.New("invalid scalar length")
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}
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ax := new(fiat.SM2P256OrderElement)
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ay := new(fiat.SM2P256OrderElement)
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res := new(fiat.SM2P256OrderElement)
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_, err := ax.SetBytes(in1)
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if err != nil {
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return nil, err
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}
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_, err = ay.SetBytes(in2)
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if err != nil {
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return nil, err
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}
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res = res.Mul(ax, ay)
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return res.Bytes(), nil
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}
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