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/**
* EdDSA-Java by str4d
*
* To the extent possible under law, the person who associated CC0 with
* EdDSA-Java has waived all copyright and related or neighboring rights
* to EdDSA-Java.
*
* You should have received a copy of the CC0 legalcode along with this
* work. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
*
*/
package net.i2p.crypto.eddsa.math.ed25519;
import net.i2p.crypto.eddsa.math.*;
import org.hamcrest.core.IsEqual;
import org.junit.*;
import java.math.BigInteger;
import java.security.SecureRandom;
/**
* Tests rely on the BigInteger class.
*/
public class Ed25519LittleEndianEncodingTest {
private static final SecureRandom random = new SecureRandom();
@Test
public void encodeReturnsCorrectByteArrayForSimpleFieldElements() {
// Arrange:
final int[] t1 = new int[10];
final int[] t2 = new int[10];
t2[0] = 1;
final FieldElement fieldElement1 = new Ed25519FieldElement(MathUtils.getField(), t1);
final FieldElement fieldElement2 = new Ed25519FieldElement(MathUtils.getField(), t2);
// Act:
final byte[] bytes1 = MathUtils.getField().getEncoding().encode(fieldElement1);
final byte[] bytes2 = MathUtils.getField().getEncoding().encode(fieldElement2);
// Assert:
Assert.assertThat(bytes1, IsEqual.equalTo(MathUtils.toByteArray(BigInteger.ZERO)));
Assert.assertThat(bytes2, IsEqual.equalTo(MathUtils.toByteArray(BigInteger.ONE)));
}
@Test
public void encodeReturnsCorrectByteArray() {
for (int i=0; i<10000; i++){
// Arrange:
final int[] t = new int[10];
for (int j=0; j<10; j++) {
t[j] = random.nextInt(1 << 28) - (1 << 27);
}
final FieldElement fieldElement1 = new Ed25519FieldElement(MathUtils.getField(), t);
final BigInteger b = MathUtils.toBigInteger(t);
// Act:
final byte[] bytes = MathUtils.getField().getEncoding().encode(fieldElement1);
// Assert:
Assert.assertThat(bytes, IsEqual.equalTo(MathUtils.toByteArray(b.mod(MathUtils.getQ()))));
}
}
@Test
public void decodeReturnsCorrectFieldElementForSimpleByteArrays() {
// Arrange:
final byte[] bytes1 = new byte[32];
final byte[] bytes2 = new byte[32];
bytes2[0] = 1;
// Act:
final Ed25519FieldElement f1 = (Ed25519FieldElement)MathUtils.getField().getEncoding().decode(bytes1);
final Ed25519FieldElement f2 = (Ed25519FieldElement)MathUtils.getField().getEncoding().decode(bytes2);
final BigInteger b1 = MathUtils.toBigInteger(f1.t);
final BigInteger b2 = MathUtils.toBigInteger(f2.t);
// Assert:
Assert.assertThat(b1, IsEqual.equalTo(BigInteger.ZERO));
Assert.assertThat(b2, IsEqual.equalTo(BigInteger.ONE));
}
@Test
public void decodeReturnsCorrectFieldElement() {
for (int i=0; i<10000; i++) {
// Arrange:
final byte[] bytes = new byte[32];
random.nextBytes(bytes);
bytes[31] = (byte)(bytes[31] & 0x7f);
final BigInteger b1 = MathUtils.toBigInteger(bytes);
// Act:
final Ed25519FieldElement f = (Ed25519FieldElement)MathUtils.getField().getEncoding().decode(bytes);
final BigInteger b2 = MathUtils.toBigInteger(f.t).mod(MathUtils.getQ());
// Assert:
Assert.assertThat(b2, IsEqual.equalTo(b1));
}
}
@Test
public void isNegativeReturnsCorrectResult() {
for (int i=0; i<10000; i++) {
// Arrange:
final int[] t = new int[10];
for (int j=0; j<10; j++) {
t[j] = random.nextInt(1 << 28) - (1 << 27);
}
final boolean isNegative = MathUtils.toBigInteger(t).mod(MathUtils.getQ()).mod(new BigInteger("2")).equals(BigInteger.ONE);
final FieldElement f = new Ed25519FieldElement(MathUtils.getField(), t);
// Assert:
Assert.assertThat(MathUtils.getField().getEncoding().isNegative(f), IsEqual.equalTo(isNegative));
}
}
}
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