yaole
65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
package sm2a
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import (
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"io"
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"math/big"
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"xdx.jelly/xgcl/gmath"
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"xdx.jelly/xgcl/sm/sm2"
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"xdx.jelly/xgcl/sm/sm3"
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)
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type ClientSignContext struct {
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pk *sm2.PublicKey
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k1 *big.Int
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rand io.Reader
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}
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func NewClientSignContext(pk *sm2.PublicKey, r io.Reader) *ClientSignContext {
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c := &ClientSignContext{
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pk: sm2.NewPublicKey(),
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k1: new(big.Int),
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rand: r,
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}
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c.pk.Set(pk)
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return c
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}
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// Initial 客户端签名第一步，初始化，输入预处理后的待签名数据e,输出协同计算中间数据给服务端
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// 输出 = e || [k_1](P+G)
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func (c *ClientSignContext) Initial(e []byte) ([]byte, error) {
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buf := make([]byte, sm2.ByteSize())
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if n, err := c.rand.Read(buf); n != len(buf) || err != nil {
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return nil, err
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}
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c.k1.SetBytes(buf)
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c.k1.Mod(c.k1, sm2.OrderN())
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x, y := sm2.Curve().Add(c.pk.X, c.pk.Y, sm2.BaseX(), sm2.BaseY())
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x, y = sm2.Curve256.ScalarMult(x, y, c.k1.Bytes())
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out := make([]byte, sm3.Size+2*sm2.ByteSize())
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pos := copy(out, e)
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pos += copy(out[pos:], gmath.BigIntToNByte(x, sm2.ByteSize()))
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copy(out[pos:], gmath.BigIntToNByte(y, sm2.ByteSize()))
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return out, nil
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}
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// Final 客户端根据服务端协同计算结果，计算签名值
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// in = r || s1
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func (c *ClientSignContext) Final(clientKey *sm2.PrivateKey, in []byte) (*sm2.Signature, error) {
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sig := sm2.NewSignature()
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sig.R.SetBytes(in[:sm2.ByteSize()])
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s1 := new(big.Int)
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s1.SetBytes(in[sm2.ByteSize():])
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sig.S.Mul(sig.R, clientKey.D)
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sig.S.Add(sig.S, c.k1)
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sig.S.Add(sig.S, s1)
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sig.S.Sub(sig.S, sig.R)
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sig.S.Mod(sig.S, sm2.OrderN())
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sig.R.Mod(sig.R, sm2.OrderN())
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return sig, nil
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}
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