1 files changed, 405 insertions, 0 deletions
diff --git a/src/crypto/elliptic/elliptic_test.go b/src/crypto/elliptic/elliptic_test.go
new file mode 100644
index 0000000..34d70f6
--- /dev/null
+++ b/src/crypto/elliptic/elliptic_test.go
@@ -0,0 +1,405 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package elliptic
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/hex"
+	"math/big"
+	"testing"
+)
+
+// genericParamsForCurve returns the dereferenced CurveParams for
+// the specified curve. This is used to avoid the logic for
+// upgrading a curve to its specific implementation, forcing
+// usage of the generic implementation.
+func genericParamsForCurve(c Curve) *CurveParams {
+	d := *(c.Params())
+	return &d
+}
+
+func testAllCurves(t *testing.T, f func(*testing.T, Curve)) {
+	tests := []struct {
+		name  string
+		curve Curve
+	}{
+		{"P256", P256()},
+		{"P256/Params", genericParamsForCurve(P256())},
+		{"P224", P224()},
+		{"P224/Params", genericParamsForCurve(P224())},
+		{"P384", P384()},
+		{"P384/Params", genericParamsForCurve(P384())},
+		{"P521", P521()},
+		{"P521/Params", genericParamsForCurve(P521())},
+	}
+	if testing.Short() {
+		tests = tests[:1]
+	}
+	for _, test := range tests {
+		curve := test.curve
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+			f(t, curve)
+		})
+	}
+}
+
+func TestOnCurve(t *testing.T) {
+	testAllCurves(t, func(t *testing.T, curve Curve) {
+		if !curve.IsOnCurve(curve.Params().Gx, curve.Params().Gy) {
+			t.Error("basepoint is not on the curve")
+		}
+	})
+}
+
+func TestOffCurve(t *testing.T) {
+	testAllCurves(t, func(t *testing.T, curve Curve) {
+		x, y := new(big.Int).SetInt64(1), new(big.Int).SetInt64(1)
+		if curve.IsOnCurve(x, y) {
+			t.Errorf("point off curve is claimed to be on the curve")
+		}
+
+		byteLen := (curve.Params().BitSize + 7) / 8
+		b := make([]byte, 1+2*byteLen)
+		b[0] = 4 // uncompressed point
+		x.FillBytes(b[1 : 1+byteLen])
+		y.FillBytes(b[1+byteLen : 1+2*byteLen])
+
+		x1, y1 := Unmarshal(curve, b)
+		if x1 != nil || y1 != nil {
+			t.Errorf("unmarshaling a point not on the curve succeeded")
+		}
+	})
+}
+
+func TestInfinity(t *testing.T) {
+	testAllCurves(t, testInfinity)
+}
+
+func isInfinity(x, y *big.Int) bool {
+	return x.Sign() == 0 && y.Sign() == 0
+}
+
+func testInfinity(t *testing.T, curve Curve) {
+	x0, y0 := new(big.Int), new(big.Int)
+	xG, yG := curve.Params().Gx, curve.Params().Gy
+
+	if !isInfinity(curve.ScalarMult(xG, yG, curve.Params().N.Bytes())) {
+		t.Errorf("x^q != ∞")
+	}
+	if !isInfinity(curve.ScalarMult(xG, yG, []byte{0})) {
+		t.Errorf("x^0 != ∞")
+	}
+
+	if !isInfinity(curve.ScalarMult(x0, y0, []byte{1, 2, 3})) {
+		t.Errorf("∞^k != ∞")
+	}
+	if !isInfinity(curve.ScalarMult(x0, y0, []byte{0})) {
+		t.Errorf("∞^0 != ∞")
+	}
+
+	if !isInfinity(curve.ScalarBaseMult(curve.Params().N.Bytes())) {
+		t.Errorf("b^q != ∞")
+	}
+	if !isInfinity(curve.ScalarBaseMult([]byte{0})) {
+		t.Errorf("b^0 != ∞")
+	}
+
+	if !isInfinity(curve.Double(x0, y0)) {
+		t.Errorf("2∞ != ∞")
+	}
+	// There is no other point of order two on the NIST curves (as they have
+	// cofactor one), so Double can't otherwise return the point at infinity.
+
+	nMinusOne := new(big.Int).Sub(curve.Params().N, big.NewInt(1))
+	x, y := curve.ScalarMult(xG, yG, nMinusOne.Bytes())
+	x, y = curve.Add(x, y, xG, yG)
+	if !isInfinity(x, y) {
+		t.Errorf("x^(q-1) + x != ∞")
+	}
+	x, y = curve.Add(xG, yG, x0, y0)
+	if x.Cmp(xG) != 0 || y.Cmp(yG) != 0 {
+		t.Errorf("x+∞ != x")
+	}
+	x, y = curve.Add(x0, y0, xG, yG)
+	if x.Cmp(xG) != 0 || y.Cmp(yG) != 0 {
+		t.Errorf("∞+x != x")
+	}
+
+	if curve.IsOnCurve(x0, y0) {
+		t.Errorf("IsOnCurve(∞) == true")
+	}
+
+	if xx, yy := Unmarshal(curve, 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 {
+		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 {
+		t.Errorf("Unmarshal((0,0)) did not return an error")
+	}
+}
+
+func TestMarshal(t *testing.T) {
+	testAllCurves(t, func(t *testing.T, curve Curve) {
+		_, x, y, err := GenerateKey(curve, rand.Reader)
+		if err != nil {
+			t.Fatal(err)
+		}
+		serialized := Marshal(curve, x, y)
+		xx, yy := Unmarshal(curve, serialized)
+		if xx == nil {
+			t.Fatal("failed to unmarshal")
+		}
+		if xx.Cmp(x) != 0 || yy.Cmp(y) != 0 {
+			t.Fatal("unmarshal returned different values")
+		}
+	})
+}
+
+func TestUnmarshalToLargeCoordinates(t *testing.T) {
+	// See https://golang.org/issues/20482.
+	testAllCurves(t, testUnmarshalToLargeCoordinates)
+}
+
+func testUnmarshalToLargeCoordinates(t *testing.T, curve Curve) {
+	p := curve.Params().P
+	byteLen := (p.BitLen() + 7) / 8
+
+	// Set x to be greater than curve's parameter P – specifically, to P+5.
+	// Set y to mod_sqrt(x^3 - 3x + B)) so that (x mod P = 5 , y) is on the
+	// curve.
+	x := new(big.Int).Add(p, big.NewInt(5))
+	y := curve.Params().polynomial(x)
+	y.ModSqrt(y, p)
+
+	invalid := make([]byte, byteLen*2+1)
+	invalid[0] = 4 // uncompressed encoding
+	x.FillBytes(invalid[1 : 1+byteLen])
+	y.FillBytes(invalid[1+byteLen:])
+
+	if X, Y := Unmarshal(curve, invalid); X != nil || Y != nil {
+		t.Errorf("Unmarshal accepts invalid X coordinate")
+	}
+
+	if curve == p256 {
+		// This is a point on the curve with a small y value, small enough that
+		// we can add p and still be within 32 bytes.
+		x, _ = new(big.Int).SetString("31931927535157963707678568152204072984517581467226068221761862915403492091210", 10)
+		y, _ = new(big.Int).SetString("5208467867388784005506817585327037698770365050895731383201516607147", 10)
+		y.Add(y, p)
+
+		if p.Cmp(y) > 0 || y.BitLen() != 256 {
+			t.Fatal("y not within expected range")
+		}
+
+		// marshal
+		x.FillBytes(invalid[1 : 1+byteLen])
+		y.FillBytes(invalid[1+byteLen:])
+
+		if X, Y := Unmarshal(curve, invalid); X != nil || Y != nil {
+			t.Errorf("Unmarshal accepts invalid Y coordinate")
+		}
+	}
+}
+
+// TestInvalidCoordinates tests big.Int values that are not valid field elements
+// (negative or bigger than P). They are expected to return false from
+// IsOnCurve, all other behavior is undefined.
+func TestInvalidCoordinates(t *testing.T) {
+	testAllCurves(t, testInvalidCoordinates)
+}
+
+func testInvalidCoordinates(t *testing.T, curve Curve) {
+	checkIsOnCurveFalse := func(name string, x, y *big.Int) {
+		if curve.IsOnCurve(x, y) {
+			t.Errorf("IsOnCurve(%s) unexpectedly returned true", name)
+		}
+	}
+
+	p := curve.Params().P
+	_, x, y, _ := GenerateKey(curve, rand.Reader)
+	xx, yy := new(big.Int), new(big.Int)
+
+	// Check if the sign is getting dropped.
+	xx.Neg(x)
+	checkIsOnCurveFalse("-x, y", xx, y)
+	yy.Neg(y)
+	checkIsOnCurveFalse("x, -y", x, yy)
+
+	// Check if negative values are reduced modulo P.
+	xx.Sub(x, p)
+	checkIsOnCurveFalse("x-P, y", xx, y)
+	yy.Sub(y, p)
+	checkIsOnCurveFalse("x, y-P", x, yy)
+
+	// Check if positive values are reduced modulo P.
+	xx.Add(x, p)
+	checkIsOnCurveFalse("x+P, y", xx, y)
+	yy.Add(y, p)
+	checkIsOnCurveFalse("x, y+P", x, yy)
+
+	// Check if the overflow is dropped.
+	xx.Add(x, new(big.Int).Lsh(big.NewInt(1), 535))
+	checkIsOnCurveFalse("x+2⁵³⁵, y", xx, y)
+	yy.Add(y, new(big.Int).Lsh(big.NewInt(1), 535))
+	checkIsOnCurveFalse("x, y+2⁵³⁵", x, yy)
+
+	// Check if P is treated like zero (if possible).
+	// y^2 = x^3 - 3x + B
+	// y = mod_sqrt(x^3 - 3x + B)
+	// y = mod_sqrt(B) if x = 0
+	// If there is no modsqrt, there is no point with x = 0, can't test x = P.
+	if yy := new(big.Int).ModSqrt(curve.Params().B, p); yy != nil {
+		if !curve.IsOnCurve(big.NewInt(0), yy) {
+			t.Fatal("(0, mod_sqrt(B)) is not on the curve?")
+		}
+		checkIsOnCurveFalse("P, y", p, yy)
+	}
+}
+
+func TestMarshalCompressed(t *testing.T) {
+	t.Run("P-256/03", func(t *testing.T) {
+		data, _ := hex.DecodeString("031e3987d9f9ea9d7dd7155a56a86b2009e1e0ab332f962d10d8beb6406ab1ad79")
+		x, _ := new(big.Int).SetString("13671033352574878777044637384712060483119675368076128232297328793087057702265", 10)
+		y, _ := new(big.Int).SetString("66200849279091436748794323380043701364391950689352563629885086590854940586447", 10)
+		testMarshalCompressed(t, P256(), x, y, data)
+	})
+	t.Run("P-256/02", func(t *testing.T) {
+		data, _ := hex.DecodeString("021e3987d9f9ea9d7dd7155a56a86b2009e1e0ab332f962d10d8beb6406ab1ad79")
+		x, _ := new(big.Int).SetString("13671033352574878777044637384712060483119675368076128232297328793087057702265", 10)
+		y, _ := new(big.Int).SetString("49591239931264812013903123569363872165694192725937750565648544718012157267504", 10)
+		testMarshalCompressed(t, P256(), x, y, data)
+	})
+
+	t.Run("Invalid", func(t *testing.T) {
+		data, _ := hex.DecodeString("02fd4bf61763b46581fd9174d623516cf3c81edd40e29ffa2777fb6cb0ae3ce535")
+		X, Y := UnmarshalCompressed(P256(), data)
+		if X != nil || Y != nil {
+			t.Error("expected an error for invalid encoding")
+		}
+	})
+
+	if testing.Short() {
+		t.Skip("skipping other curves on short test")
+	}
+
+	testAllCurves(t, func(t *testing.T, curve Curve) {
+		_, x, y, err := GenerateKey(curve, rand.Reader)
+		if err != nil {
+			t.Fatal(err)
+		}
+		testMarshalCompressed(t, curve, x, y, nil)
+	})
+
+}
+
+func testMarshalCompressed(t *testing.T, curve Curve, x, y *big.Int, want []byte) {
+	if !curve.IsOnCurve(x, y) {
+		t.Fatal("invalid test point")
+	}
+	got := MarshalCompressed(curve, x, y)
+	if want != nil && !bytes.Equal(got, want) {
+		t.Errorf("got unexpected MarshalCompressed result: got %x, want %x", got, want)
+	}
+
+	X, Y := UnmarshalCompressed(curve, got)
+	if X == nil || Y == nil {
+		t.Fatalf("UnmarshalCompressed failed unexpectedly")
+	}
+
+	if !curve.IsOnCurve(X, Y) {
+		t.Error("UnmarshalCompressed returned a point not on the curve")
+	}
+	if X.Cmp(x) != 0 || Y.Cmp(y) != 0 {
+		t.Errorf("point did not round-trip correctly: got (%v, %v), want (%v, %v)", X, Y, x, y)
+	}
+}
+
+func TestLargeIsOnCurve(t *testing.T) {
+	testAllCurves(t, func(t *testing.T, curve Curve) {
+		large := big.NewInt(1)
+		large.Lsh(large, 1000)
+		if curve.IsOnCurve(large, large) {
+			t.Errorf("(2^1000, 2^1000) is reported on the curve")
+		}
+	})
+}
+
+func benchmarkAllCurves(b *testing.B, f func(*testing.B, Curve)) {
+	tests := []struct {
+		name  string
+		curve Curve
+	}{
+		{"P256", P256()},
+		{"P224", P224()},
+		{"P384", P384()},
+		{"P521", P521()},
+	}
+	for _, test := range tests {
+		curve := test.curve
+		b.Run(test.name, func(b *testing.B) {
+			f(b, curve)
+		})
+	}
+}
+
+func BenchmarkScalarBaseMult(b *testing.B) {
+	benchmarkAllCurves(b, func(b *testing.B, curve Curve) {
+		priv, _, _, _ := GenerateKey(curve, rand.Reader)
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			x, _ := curve.ScalarBaseMult(priv)
+			// Prevent the compiler from optimizing out the operation.
+			priv[0] ^= byte(x.Bits()[0])
+		}
+	})
+}
+
+func BenchmarkScalarMult(b *testing.B) {
+	benchmarkAllCurves(b, func(b *testing.B, curve Curve) {
+		_, x, y, _ := GenerateKey(curve, rand.Reader)
+		priv, _, _, _ := GenerateKey(curve, rand.Reader)
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			x, y = curve.ScalarMult(x, y, priv)
+		}
+	})
+}
+
+func BenchmarkMarshalUnmarshal(b *testing.B) {
+	benchmarkAllCurves(b, func(b *testing.B, curve Curve) {
+		_, x, y, _ := GenerateKey(curve, rand.Reader)
+		b.Run("Uncompressed", func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				buf := Marshal(curve, x, y)
+				xx, yy := Unmarshal(curve, buf)
+				if xx.Cmp(x) != 0 || yy.Cmp(y) != 0 {
+					b.Error("Unmarshal output different from Marshal input")
+				}
+			}
+		})
+		b.Run("Compressed", func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				buf := MarshalCompressed(curve, x, y)
+				xx, yy := UnmarshalCompressed(curve, buf)
+				if xx.Cmp(x) != 0 || yy.Cmp(y) != 0 {
+					b.Error("Unmarshal output different from Marshal input")
+				}
+			}
+		})
+	})
+}