yaole
48 lines
1.2 KiB
Go
48 lines
1.2 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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// ServerSign 服务端根据客户端的协同签名中间数据计算
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// in = e || [k_1](P+G)
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// out = r || k_2 + r*d_s
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func ServerSign(serverKey *sm2.PrivateKey, pk *sm2.PublicKey, in []byte, rand io.Reader) ([]byte, error) {
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k2 := make([]byte, sm2.ByteSize())
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if n, err := rand.Read(k2); n != len(k2) || err != nil {
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return nil, err
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}
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var x, y *big.Int
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tx := new(big.Int)
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ty := new(big.Int)
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r := new(big.Int)
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r.SetBytes(in[:sm3.Size])
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tx.SetBytes(in[sm3.Size : sm3.Size+sm2.ByteSize()])
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ty.SetBytes(in[sm3.Size+sm2.ByteSize() : sm3.Size+2*sm2.ByteSize()])
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x, y = sm2.Curve().Add(pk.X, pk.Y, sm2.BaseX(), sm2.BaseY())
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x, y = sm2.Curve256.ScalarMult(x, y, k2)
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x, y = sm2.Curve().Add(x, y, tx, ty)
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r.Add(r, x)
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r.Mod(r, sm2.OrderN())
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x.Mul(r, serverKey.D)
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y.SetBytes(k2)
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x.Add(x, y)
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x.Mod(x, sm2.OrderN())
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out := make([]byte, 2*sm2.ByteSize())
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copy(out, gmath.BigIntToNByte(r, sm2.ByteSize()))
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copy(out[sm2.ByteSize():], gmath.BigIntToNByte(x, sm2.ByteSize()))
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// 清除中间变量
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gmath.ClearBigInt(x)
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gmath.ClearBigInt(y)
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gmath.ClearBigInt(tx)
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gmath.ClearBigInt(ty)
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gmath.ClearBigInt(r)
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return out, nil
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}
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