github.com/defanghe/fabric@v2.1.1+incompatible/internal/cryptogen/csp/csp_internal_test.go (about)

     1  /*
     2  Copyright IBM Corp. All Rights Reserved.
     3  
     4  SPDX-License-Identifier: Apache-2.0
     5  */
     6  package csp
     7  
     8  import (
     9  	"crypto/ecdsa"
    10  	"crypto/elliptic"
    11  	"math/big"
    12  	"testing"
    13  
    14  	"github.com/stretchr/testify/assert"
    15  )
    16  
    17  func TestToLowS(t *testing.T) {
    18  	curve := elliptic.P256()
    19  	halfOrder := new(big.Int).Div(curve.Params().N, big.NewInt(2))
    20  
    21  	for _, test := range []struct {
    22  		name        string
    23  		sig         ECDSASignature
    24  		expectedSig ECDSASignature
    25  	}{
    26  		{
    27  			name: "HighS",
    28  			sig: ECDSASignature{
    29  				R: big.NewInt(1),
    30  				// set S to halfOrder + 1
    31  				S: new(big.Int).Add(halfOrder, big.NewInt(1)),
    32  			},
    33  			// expected signature should be (sig.R, -sig.S mod N)
    34  			expectedSig: ECDSASignature{
    35  				R: big.NewInt(1),
    36  				S: new(big.Int).Mod(new(big.Int).Neg(new(big.Int).Add(halfOrder, big.NewInt(1))), curve.Params().N),
    37  			},
    38  		},
    39  		{
    40  			name: "LowS",
    41  			sig: ECDSASignature{
    42  				R: big.NewInt(1),
    43  				// set S to halfOrder - 1
    44  				S: new(big.Int).Sub(halfOrder, big.NewInt(1)),
    45  			},
    46  			// expected signature should be sig
    47  			expectedSig: ECDSASignature{
    48  				R: big.NewInt(1),
    49  				S: new(big.Int).Sub(halfOrder, big.NewInt(1)),
    50  			},
    51  		},
    52  		{
    53  			name: "HalfOrder",
    54  			sig: ECDSASignature{
    55  				R: big.NewInt(1),
    56  				// set S to halfOrder
    57  				S: halfOrder,
    58  			},
    59  			// expected signature should be sig
    60  			expectedSig: ECDSASignature{
    61  				R: big.NewInt(1),
    62  				S: halfOrder,
    63  			},
    64  		},
    65  	} {
    66  		t.Run(test.name, func(t *testing.T) {
    67  			curve := elliptic.P256()
    68  			key := ecdsa.PublicKey{
    69  				Curve: curve,
    70  			}
    71  			assert.Equal(t, test.expectedSig, toLowS(key, test.sig))
    72  		})
    73  	}
    74  }