sm2, sm2ec: remove useless codes since go 1.19

docs/cfca.md

@@ -104,7 +104,8 @@ SADK 3.2之后的版本，支持下列SM2密文格式(encryptedType)：
 * 0x02/0x03 - C1为压缩点格式，具体是C1C3C2还是C1C2C3取决于解密时的选项参数，默认为C1C3C2。
 
 ### 生成双密钥CSR （v0.29.6+）
-`cfca.CreateCertificateRequest`，和CFCA SADK不同，调用者需要自行先生成两对密钥对，一对用于签名证书，一对用于加解密CFCA生成的加密用私钥文件（CFCA加密，申请者解密）。
+`cfca.CreateCertificateRequest`，和CFCA SADK不同，调用者需要自行先生成两对密钥对，一对用于签名证书，一对用于加解密CFCA生成的加密用私钥文件（CFCA加密，申请者解密）。这个方法对应CFCA的`cfca.sadk.util.P10Request.generateDoublePKCS10Request`方法。按我的理解，非国密（RSA）应该不需要支持这种双密钥对机制，不过既然**CFCA SADK**支持，本软件库从**v0.30.0**开始也支持。
+
 使用`cfca.ParseEscrowPrivateKey`解析CFCA返回的加密用私钥。
 
 ### SM2私钥、证书的解析

sm2/sm2_legacy.go

@@ -10,9 +10,9 @@ import (
 	"math/big"
 	"strings"
 
+	_subtle "github.com/emmansun/gmsm/internal/subtle"
 	"github.com/emmansun/gmsm/sm2/sm2ec"
 	"github.com/emmansun/gmsm/sm3"
-	_subtle "github.com/emmansun/gmsm/internal/subtle"
 	"golang.org/x/crypto/cryptobyte"
 	"golang.org/x/crypto/cryptobyte/asn1"
 )
@@ -392,7 +392,7 @@ func bytesToPoint(curve elliptic.Curve, bytes []byte) (*big.Int, *big.Int, int,
 		data := make([]byte, 1+byteLen*2)
 		data[0] = uncompressed
 		copy(data[1:], bytes[1:1+byteLen*2])
-		x, y := sm2ec.Unmarshal(curve, data)
+		x, y := elliptic.Unmarshal(curve, data)
 		if x == nil || y == nil {
 			return nil, nil, 0, fmt.Errorf("sm2: point is not on curve %s", curve.Params().Name)
 		}
@@ -404,7 +404,7 @@ func bytesToPoint(curve elliptic.Curve, bytes []byte) (*big.Int, *big.Int, int,
 		// Make sure it's NIST curve or SM2 P-256 curve
 		if strings.HasPrefix(curve.Params().Name, "P-") || strings.EqualFold(curve.Params().Name, sm2ec.P256().Params().Name) {
 			// y² = x³ - 3x + b, prime curves
-			x, y := sm2ec.UnmarshalCompressed(curve, bytes[:1+byteLen])
+			x, y := elliptic.UnmarshalCompressed(curve, bytes[:1+byteLen])
 			if x == nil || y == nil {
 				return nil, nil, 0, fmt.Errorf("sm2: point is not on curve %s", curve.Params().Name)
 			}

sm2/sm2ec/elliptic.go

@@ -2,7 +2,6 @@ package sm2ec
 
 import (
 	"crypto/elliptic"
-	"math/big"
 	"sync"
 )
 
@@ -16,29 +15,3 @@ func P256() elliptic.Curve {
 	initonce.Do(initAll)
 	return sm2p256
 }
-
-// Since golang 1.19
-// unmarshaler is implemented by curves with their own constant-time Unmarshal.
-// There isn't an equivalent interface for Marshal/MarshalCompressed because
-// that doesn't involve any mathematical operations, only FillBytes and Bit.
-type unmarshaler interface {
-	Unmarshal([]byte) (x, y *big.Int)
-	UnmarshalCompressed([]byte) (x, y *big.Int)
-}
-
-func Unmarshal(curve elliptic.Curve, data []byte) (x, y *big.Int) {
-	if c, ok := curve.(unmarshaler); ok {
-		return c.Unmarshal(data)
-	}
-	return elliptic.Unmarshal(curve, data)
-}
-
-// UnmarshalCompressed converts a point, serialized by MarshalCompressed, into
-// an x, y pair. It is an error if the point is not in compressed form, is not
-// on the curve, or is the point at infinity. On error, x = nil.
-func UnmarshalCompressed(curve elliptic.Curve, data []byte) (x, y *big.Int) {
-	if c, ok := curve.(unmarshaler); ok {
-		return c.UnmarshalCompressed(data)
-	}
-	return elliptic.UnmarshalCompressed(curve, data)
-}

sm2/sm2ec/elliptic_test.go

@@ -61,7 +61,7 @@ func TestOffCurve(t *testing.T) {
 		x.FillBytes(b[1 : 1+byteLen])
 		y.FillBytes(b[1+byteLen : 1+2*byteLen])
 
-		x1, y1 := Unmarshal(curve, b)
+		x1, y1 := elliptic.Unmarshal(curve, b)
 		if x1 != nil || y1 != nil {
 			t.Errorf("unmarshaling a point not on the curve succeeded")
 		}
@@ -126,18 +126,18 @@ func testInfinity(t *testing.T, curve elliptic.Curve) {
 		t.Errorf("IsOnCurve(∞) == true")
 	}
 
-	if xx, yy := Unmarshal(curve, elliptic.Marshal(curve, x0, y0)); xx != nil || yy != nil {
+	if xx, yy := elliptic.Unmarshal(curve, elliptic.Marshal(curve, x0, y0)); xx != nil || yy != nil {
 		t.Errorf("Unmarshal(Marshal(∞)) did not return an error")
 	}
 	// We don't test UnmarshalCompressed(MarshalCompressed(∞)) because there are
 	// two valid points with x = 0.
-	if xx, yy := Unmarshal(curve, []byte{0x00}); xx != nil || yy != nil {
+	if xx, yy := elliptic.Unmarshal(curve, []byte{0x00}); xx != nil || yy != nil {
 		t.Errorf("Unmarshal(∞) did not return an error")
 	}
 	byteLen := (curve.Params().BitSize + 7) / 8
 	buf := make([]byte, byteLen*2+1)
 	buf[0] = 4 // Uncompressed format.
-	if xx, yy := Unmarshal(curve, buf); xx != nil || yy != nil {
+	if xx, yy := elliptic.Unmarshal(curve, buf); xx != nil || yy != nil {
 		t.Errorf("Unmarshal((0,0)) did not return an error")
 	}
 }
@@ -149,7 +149,7 @@ func TestMarshal(t *testing.T) {
 			t.Fatal(err)
 		}
 		serialized := elliptic.Marshal(curve, x, y)
-		xx, yy := Unmarshal(curve, serialized)
+		xx, yy := elliptic.Unmarshal(curve, serialized)
 		if xx == nil {
 			t.Fatal("failed to unmarshal")
 		}
@@ -230,7 +230,7 @@ func TestMarshalCompressed(t *testing.T) {
 
 	t.Run("Invalid", func(t *testing.T) {
 		data, _ := hex.DecodeString("02fd4bf61763b46581fd9174d623516cf3c81edd40e29ffa2777fb6cb0ae3ce535")
-		X, Y := UnmarshalCompressed(P256(), data)
+		X, Y := elliptic.UnmarshalCompressed(P256(), data)
 		if X != nil || Y != nil {
 			t.Error("expected an error for invalid encoding")
 		}
@@ -258,7 +258,7 @@ func testMarshalCompressed(t *testing.T, curve elliptic.Curve, x, y *big.Int, wa
 		t.Errorf("got unexpected MarshalCompressed result: got %x, want %x", got, want)
 	}
 
-	X, Y := UnmarshalCompressed(curve, got)
+	X, Y := elliptic.UnmarshalCompressed(curve, got)
 	if X == nil || Y == nil {
 		t.Fatalf("UnmarshalCompressed failed unexpectedly")
 	}
@@ -328,7 +328,7 @@ func BenchmarkMarshalUnmarshal(b *testing.B) {
 			b.ReportAllocs()
 			for i := 0; i < b.N; i++ {
 				buf := elliptic.Marshal(curve, x, y)
-				xx, yy := Unmarshal(curve, buf)
+				xx, yy := elliptic.Unmarshal(curve, buf)
 				if xx.Cmp(x) != 0 || yy.Cmp(y) != 0 {
 					b.Error("Unmarshal output different from Marshal input")
 				}
@@ -338,7 +338,7 @@ func BenchmarkMarshalUnmarshal(b *testing.B) {
 			b.ReportAllocs()
 			for i := 0; i < b.N; i++ {
 				buf := elliptic.MarshalCompressed(curve, x, y)
-				xx, yy := UnmarshalCompressed(curve, buf)
+				xx, yy := elliptic.UnmarshalCompressed(curve, buf)
 				if xx.Cmp(x) != 0 || yy.Cmp(y) != 0 {
 					b.Error("Unmarshal output different from Marshal input")
 				}