public void ModifiedCiphertextFails()
{
var rnd = new Random();
var key = new byte[Snuffle.KEY_SIZE_IN_BYTES];
rnd.NextBytes(key);
var aad = new byte[16];
rnd.NextBytes(aad);
var message = new byte[32];
rnd.NextBytes(message);
var aead = new XChaCha20Poly1305(key);
var ciphertext = aead.Encrypt(message, aad);
// Flipping bits
for (var b = 0; b < ciphertext.Length; b++)
{
for (var bit = 0; bit < 8; bit++)
{
var modified = new byte[ciphertext.Length];
Array.Copy(ciphertext, modified, ciphertext.Length);
modified[b] ^= (byte)(1 << bit);
Assert.Throws <CryptographicException>(() => aead.Decrypt(modified, aad), SnufflePoly1305.AEAD_EXCEPTION_INVALID_TAG);
}
}
// Truncate the message
for (var length = 0; length < ciphertext.Length; length++)
{
var modified = new byte[length];
Array.Copy(ciphertext, modified, length);
Assert.Throws <CryptographicException>(() => aead.Decrypt(modified, aad), SnufflePoly1305.AEAD_EXCEPTION_INVALID_TAG);
}
// Modify AAD
for (var b = 0; b < aad.Length; b++)
{
for (var bit = 0; bit < 8; bit++)
{
var modified = new byte[aad.Length];
Array.Copy(aad, modified, aad.Length);
modified[b] ^= (byte)(1 << bit);
Assert.Throws <CryptographicException>(() => aead.Decrypt(modified, aad), SnufflePoly1305.AEAD_EXCEPTION_INVALID_TAG);
}
}
}
public void Decrypt(Tests.Vectors.XChaCha20Poly1305TestVector test)
{
var aead = new XChaCha20Poly1305(test.Key);
var plaintext = new byte[test.CipherText.Length];
aead.Decrypt(test.Nonce, test.CipherText, test.Tag, plaintext, test.Aad);
}
public void DecryptWhenNonceIsEmptyFails()
{
// Arrange, Act & Assert
var aead = new XChaCha20Poly1305(new byte[Snuffle.KEY_SIZE_IN_BYTES]);
Assert.Throws <CryptographicException>(() => aead.Decrypt(new byte[50], new byte[0], new byte[0]), EXCEPTION_MESSAGE_NONCE_LENGTH);
}
public void DecryptWhenNonceLengthIsInvalidFails()
{
// Arrange, Act & Assert
var aead = new XChaCha20Poly1305(new byte[Snuffle.KEY_SIZE_IN_BYTES]);
Assert.Throws <CryptographicException>(() => aead.Decrypt(new byte[50], new byte[0], new byte[24 + TestHelpers.ReturnRandomPositiveNegative()]), EXCEPTION_MESSAGE_NONCE_LENGTH);
}
public void EncryptDecryptLongMessagesWithNonceTest()
{
var rnd = new Random();
var dataSize = 16;
while (dataSize <= (1 << 24))
{
var plaintext = new byte[dataSize];
rnd.NextBytes(plaintext);
var aad = new byte[dataSize / 3];
rnd.NextBytes(aad);
var nonce = new byte[24];
rnd.NextBytes(nonce);
var key = new byte[Snuffle.KEY_SIZE_IN_BYTES];
rnd.NextBytes(key);
var aead = new XChaCha20Poly1305(key);
var ciphertext = aead.Encrypt(plaintext, aad, nonce);
var decrypted = aead.Decrypt(ciphertext, aad, nonce);
//Assert.AreEqual(plaintext, decrypted);
Assert.IsTrue(CryptoBytes.ConstantTimeEquals(plaintext, decrypted));
dataSize += 5 * dataSize / 11;
}
}
public void EncryptDecryptWithNonceTest()
{
var rnd = new Random();
var key = new byte[Snuffle.KEY_SIZE_IN_BYTES];
rnd.NextBytes(key);
var aead = new XChaCha20Poly1305(key);
for (var i = 0; i < 100; i++)
{
var message = new byte[100];
rnd.NextBytes(message);
var aad = new byte[16];
rnd.NextBytes(aad);
var nonce = new byte[24];
rnd.NextBytes(nonce);
var ciphertext = aead.Encrypt(message, aad, nonce);
var decrypted = aead.Decrypt(ciphertext, aad, nonce);
//Assert.AreEqual(message, decrypted);
Assert.IsTrue(CryptoBytes.ConstantTimeEquals(message, decrypted));
}
}
public void DecryptWithNonceWhenCiphertextIsTooShortFails()
{
// Arrange & Act
var cipher = new XChaCha20Poly1305(new byte[Snuffle.KEY_SIZE_IN_BYTES]);
// Assert
Assert.Throws <CryptographicException>(() => cipher.Decrypt(new byte[27], new byte[1], new byte[1]));
}
public void XChaCha20Poly1305TestVectors()
{
// From libsodium's test/default/aead_xchacha20poly1305.c and https://tools.ietf.org/html/draft-arciszewski-xchacha-01.
// Arrange
foreach (var test in XChaCha20Poly1305TestVector.TestVectors)
{
// Act
var aead = new XChaCha20Poly1305(test.Key);
//var message = aead.Decrypt(CryptoBytes.Combine(test.CipherText, test.Tag), test.Aad, test.Nonce); // same as below...
var output = aead.Decrypt(CryptoBytes.Combine(test.Nonce, test.CipherText, test.Tag), test.Aad);
// Assert
//Assert.That(output, Is.EqualTo(test.PlainText));
Assert.IsTrue(CryptoBytes.ConstantTimeEquals(test.PlainText, output));
}
}
public static void Test(string[] testVector)
{
var plaintext = testVector[0];
var aad = testVector[1];
var key = testVector[2];
var nonce = testVector[3];
var ciphertext = testVector[4];
var tag = testVector[5];
var a = new XChaCha20Poly1305();
using (var k = Key.Import(a, key.DecodeHex(), KeyBlobFormat.RawSymmetricKey))
{
var b = a.Encrypt(k, new Nonce(nonce.DecodeHex(), 0), aad.DecodeHex(), plaintext.DecodeHex());
Assert.Equal((ciphertext + tag).DecodeHex(), b);
Assert.True(a.Decrypt(k, new Nonce(nonce.DecodeHex(), 0), aad.DecodeHex(), b, out var r));
Assert.Equal(plaintext.DecodeHex(), r);
}
}
public void ModifiedAssociatedDataFails()
{
var rnd = new Random();
var key = new byte[Snuffle.KEY_SIZE_IN_BYTES];
rnd.NextBytes(key);
var aead = new XChaCha20Poly1305(key);
var aad = new byte[0];
for (var msgSize = 0; msgSize < 75; msgSize++)
{
var message = new byte[msgSize];
rnd.NextBytes(message);
// encrypting with aad as a 0-length array
var ciphertext = aead.Encrypt(message, aad);
var decrypted = aead.Decrypt(ciphertext, aad);
//Assert.AreEqual(message, decrypted);
Assert.IsTrue(CryptoBytes.ConstantTimeEquals(message, decrypted));
var decrypted2 = aead.Decrypt(ciphertext, null);
//Assert.AreEqual(message, decrypted2);
Assert.IsTrue(CryptoBytes.ConstantTimeEquals(message, decrypted2));
var badAad = new byte[] { 1, 2, 3 };
Assert.Throws <CryptographicException>(() => aead.Decrypt(ciphertext, badAad), SnufflePoly1305.AEAD_EXCEPTION_INVALID_TAG);
// encrypting with aad equal to null
ciphertext = aead.Encrypt(message, null);
decrypted = aead.Decrypt(ciphertext, aad);
//Assert.AreEqual(message, decrypted);
Assert.IsTrue(CryptoBytes.ConstantTimeEquals(message, decrypted));
decrypted2 = aead.Decrypt(ciphertext, null);
//Assert.AreEqual(message, decrypted2);
Assert.IsTrue(CryptoBytes.ConstantTimeEquals(message, decrypted2));
Assert.Throws <CryptographicException>(() => aead.Decrypt(ciphertext, badAad), SnufflePoly1305.AEAD_EXCEPTION_INVALID_TAG);
}
}
public byte[] Decrypt(Tests.Vectors.XChaCha20Poly1305TestVector test)
{
var aead = new XChaCha20Poly1305(test.Key);
return(aead.Decrypt(CryptoBytes.Combine(test.Nonce, test.CipherText, test.Tag), test.Aad));
}