diff options
Diffstat (limited to 'src/crypto/elliptic/elliptic_test.go')
-rw-r--r-- | src/crypto/elliptic/elliptic_test.go | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/src/crypto/elliptic/elliptic_test.go b/src/crypto/elliptic/elliptic_test.go index e80e7731aa..bb16b0d163 100644 --- a/src/crypto/elliptic/elliptic_test.go +++ b/src/crypto/elliptic/elliptic_test.go @@ -721,3 +721,84 @@ func testMarshalCompressed(t *testing.T, curve Curve, x, y *big.Int, want []byte t.Errorf("point did not round-trip correctly: got (%v, %v), want (%v, %v)", X, Y, x, y) } } + +func testAllCurves(t *testing.T, f func(*testing.T, Curve)) { + tests := []struct { + name string + curve Curve + }{ + {"P256", P256()}, + {"P256/Params", P256().Params()}, + {"P224", P224()}, + {"P224/Params", P224().Params()}, + {"P384", P384()}, + {"P384/Params", P384().Params()}, + {"P521", P521()}, + {"P521/Params", P521().Params()}, + } + 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) + }) + } +} + +// 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) + } +} |