yaole
42 lines
1.4 KiB
Go
42 lines
1.4 KiB
Go
package implicitcert
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import (
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"fmt"
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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/sm2/ec256"
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"xdx.jelly/xgcl/sm/sm3"
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)
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var errRandomReader = fmt.Errorf("Random Reader reads error")
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// KGCComputeUserKey compute user's partial private key and declare public key
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// TODO if r is nil, then w=KDF(H_A‖x_U‖y_U‖ks, 8×⌈(5×(log2n))/32⌉) mod n
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func KGCComputeUserKey(id []byte,
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userPartialPublickey *sm2.PublicKey,
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kgcPrivateKey *sm2.PrivateKey,
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kgcPublicKey *sm2.PublicKey,
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r io.Reader) (kgcGeneratedUserPartialPrivateKey *sm2.PrivateKey, kgcGeneratedUserDeclarePublicKey *sm2.PublicKey, err error) {
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h := sm2.PreComputeWithIdAndPubkey(id, kgcPublicKey)
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w := make([]byte, sm2.ByteSize())
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if n, err := r.Read(w); n < sm2.ByteSize() || err != nil {
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return nil, nil, errRandomReader
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}
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// x, y := sm2.Curve().CombinedMult(userPartialPublickey.X, userPartialPublickey.Y, w, []byte{1})
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x, y := ec256.CombinedMult(userPartialPublickey.X, userPartialPublickey.Y, w, []byte{1})
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digest := sm3.Sum(gmath.BigIntToNByte(x, sm2.ByteSize()), gmath.BigIntToNByte(y, sm2.ByteSize()), h)
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t := new(big.Int)
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t.SetBytes(digest[:])
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t.Mul(t, kgcPrivateKey.Get())
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t.Mod(t, sm2.OrderN())
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t.Add(t, new(big.Int).SetBytes(w))
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t.Mod(t, sm2.OrderN())
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sk := &sm2.PrivateKey{PublicKey: sm2.PublicKey{X: x, Y: y}, D: t}
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return sk, &sk.PublicKey, nil
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}
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