/** Test method for {@link GroupElement#cmov(GroupElement, int)}. */
@Test
public void testCmov() {
GroupElement a = curve.getZero(GroupElement.Representation.PRECOMP);
GroupElement b = GroupElement.precomp(curve, TWO, ZERO, TEN);
assertThat(a.cmov(b, 0), is(equalTo(a)));
assertThat(a.cmov(b, 1), is(equalTo(b)));
}
/**
* Test method for {@link GroupElement#precomp(Curve, FieldElement, FieldElement, FieldElement)}.
*/
@Test
public void testPrecomp() {
final GroupElement t = GroupElement.precomp(curve, ONE, ONE, ZERO);
assertThat(t.curve, is(equalTo(curve)));
assertThat(t.repr, is(GroupElement.Representation.PRECOMP));
assertThat(t.X, is(ONE));
assertThat(t.Y, is(ONE));
assertThat(t.Z, is(ZERO));
assertThat(t.T, is((FieldElement) null));
}
/** Test method for {@link GroupElement#select(int, int)}. */
@Test
public void testSelect() {
GroupElement B = ed25519.getB();
for (int i = 0; i < 32; i++) {
// 16^i 0 B
assertThat(
i + ",0", B.select(i, 0), is(equalTo(GroupElement.precomp(curve, ONE, ONE, ZERO))));
for (int j = 1; j < 8; j++) {
// 16^i r_i B
GroupElement t = B.select(i, j);
assertThat(i + "," + j, t, is(equalTo(B.precmp[i][j - 1])));
// -16^i r_i B
t = B.select(i, -j);
GroupElement neg =
GroupElement.precomp(
curve, B.precmp[i][j - 1].Y, B.precmp[i][j - 1].X, B.precmp[i][j - 1].Z.negate());
assertThat(i + "," + -j, t, is(equalTo(neg)));
}
}
}