@Test
public void toP2ReturnsExpectedResultIfGroupElementHasP3Representation() {
for (int i = 0; i < 10; i++) {
// Arrange:
final GroupElement g = MathUtils.getRandomGroupElement();
// Act:
final GroupElement h1 = g.toP2();
final GroupElement h2 = MathUtils.toRepresentation(g, GroupElement.Representation.P2);
// Assert:
Assert.assertThat(h1, IsEqual.equalTo(h2));
Assert.assertThat(h1.getRepresentation(), IsEqual.equalTo(GroupElement.Representation.P2));
Assert.assertThat(h1.getX(), IsEqual.equalTo(g.getX()));
Assert.assertThat(h1.getY(), IsEqual.equalTo(g.getY()));
Assert.assertThat(h1.getZ(), IsEqual.equalTo(g.getZ()));
Assert.assertThat(h1.getT(), IsEqual.equalTo(null));
}
}
@Test
public void toP3ReturnsExpectedResultIfGroupElementHasP3Representation() {
for (int i = 0; i < 10; i++) {
// Arrange:
final GroupElement g = MathUtils.getRandomGroupElement();
// Act:
final GroupElement h = g.toP3();
// Assert:
Assert.assertThat(h, IsEqual.equalTo(g));
Assert.assertThat(h.getRepresentation(), IsEqual.equalTo(GroupElement.Representation.P3));
Assert.assertThat(h, IsEqual.equalTo(g));
Assert.assertThat(h.getX(), IsEqual.equalTo(g.getX()));
Assert.assertThat(h.getY(), IsEqual.equalTo(g.getY()));
Assert.assertThat(h.getZ(), IsEqual.equalTo(g.getZ()));
Assert.assertThat(h.getT(), IsEqual.equalTo(g.getT()));
}
}
@Test
public void isOnCurveReturnsFalseForPointsNotOnTheCurve() {
for (int i = 0; i < 100; i++) {
// Arrange:
final GroupElement g = MathUtils.getRandomGroupElement();
final GroupElement h =
GroupElement.p2(curve, g.getX(), g.getY(), g.getZ().multiply(curve.getField().TWO));
// Assert (can only fail for 5*Z^2=1):
Assert.assertThat(h.isOnCurve(), IsEqual.equalTo(false));
}
}
@Test
public void toCachedReturnsExpectedResultIfGroupElementHasP3Representation() {
for (int i = 0; i < 10; i++) {
// Arrange:
final GroupElement g = MathUtils.getRandomGroupElement();
// Act:
final GroupElement h1 = g.toCached();
final GroupElement h2 = MathUtils.toRepresentation(g, GroupElement.Representation.CACHED);
// Assert:
Assert.assertThat(h1, IsEqual.equalTo(h2));
Assert.assertThat(
h1.getRepresentation(), IsEqual.equalTo(GroupElement.Representation.CACHED));
Assert.assertThat(h1, IsEqual.equalTo(g));
Assert.assertThat(h1.getX(), IsEqual.equalTo(g.getY().add(g.getX())));
Assert.assertThat(h1.getY(), IsEqual.equalTo(g.getY().subtract(g.getX())));
Assert.assertThat(h1.getZ(), IsEqual.equalTo(g.getZ()));
Assert.assertThat(h1.getT(), IsEqual.equalTo(g.getT().multiply(curve.get2D())));
}
}
@Test
public void toByteArrayReturnsExpectedResult() {
for (int i = 0; i < 100; i++) {
// Arrange:
final GroupElement g = MathUtils.getRandomGroupElement();
// Act:
final byte[] gBytes = g.toByteArray();
final byte[] bytes = MathUtils.toByteArray(MathUtils.toBigInteger(g.getY()));
if (MathUtils.toBigInteger(g.getX()).mod(new BigInteger("2")).equals(BigInteger.ONE)) {
bytes[31] |= 0x80;
}
// Assert:
Assert.assertThat(Arrays.equals(gBytes, bytes), IsEqual.equalTo(true));
}
}