private byte[] EncryptOrDecrypt(bool forEncryption, byte[] data, byte[] key, byte[] nonce)
{
if (ExpectedKeySize != key.Length)
{
throw new CryptoException("Invalid key size");
}
if (ExpectedNonceSize != nonce.Length)
{
throw new CryptoException("Invalid nonce size");
}
// We do the X-part of XChaCha20 and then use the ChaCha20 from bouncy castle
byte[] subkey = new byte[KeySizeBytes];
ChaCha20Base.HChaCha20(subkey, key, nonce);
byte[] chaChaNonce = CreateChaChaNonce(nonce);
ICipherParameters aeadParams = new AeadParameters(
new KeyParameter(subkey), MacSizeBytes * 8, chaChaNonce, null);
IAeadCipher chaCha20Poly1305 = new ChaCha20Poly1305();
chaCha20Poly1305.Init(forEncryption, aeadParams);
byte[] result = new byte[chaCha20Poly1305.GetOutputSize(data.Length)];
int len = chaCha20Poly1305.ProcessBytes(data, 0, data.Length, result, 0);
chaCha20Poly1305.DoFinal(result, len);
return(result);
}
private void OutputSizeTests()
{
byte[] K = new byte[32];
byte[] A = null;
byte[] N = new byte[12];
AeadParameters parameters = new AeadParameters(new KeyParameter(K), 16 * 8, N, A);
ChaCha20Poly1305 cipher = InitCipher(true, parameters);
if (cipher.GetUpdateOutputSize(0) != 0)
{
Fail("incorrect getUpdateOutputSize for initial 0 bytes encryption");
}
if (cipher.GetOutputSize(0) != 16)
{
Fail("incorrect getOutputSize for initial 0 bytes encryption");
}
cipher.Init(false, parameters);
if (cipher.GetUpdateOutputSize(0) != 0)
{
Fail("incorrect getUpdateOutputSize for initial 0 bytes decryption");
}
// NOTE: 0 bytes would be truncated data, but we want it to fail in the doFinal, not here
if (cipher.GetOutputSize(0) != 0)
{
Fail("fragile getOutputSize for initial 0 bytes decryption");
}
if (cipher.GetOutputSize(16) != 0)
{
Fail("incorrect getOutputSize for initial MAC-size bytes decryption");
}
}
public void ChaCha20_Poly1305_Decrypt(CBORObject alg, byte[] K)
{
ChaCha20Poly1305 cipher = new ChaCha20Poly1305();
KeyParameter ContentKey;
// The requirements from JWA
// IV is 96 bits
// Authentication tag is 128 bits
// key sizes are 128, 192 and 256 bits
ContentKey = new KeyParameter(K);
byte[] IV = new byte[96 / 8];
CBORObject cbor = FindAttribute(HeaderKeys.IV);
if (cbor == null)
{
throw new Exception("Missing IV");
}
if (cbor.Type != CBORType.ByteString)
{
throw new CoseException("IV is incorrectly formed.");
}
if (cbor.GetByteString().Length > IV.Length)
{
throw new CoseException("IV is too long.");
}
Array.Copy(cbor.GetByteString(), 0, IV, IV.Length - cbor.GetByteString().Length, cbor.GetByteString().Length);
AeadParameters parameters = new AeadParameters(ContentKey, 128, IV, getAADBytes());
cipher.Init(false, parameters);
byte[] C = new byte[cipher.GetOutputSize(RgbEncrypted.Length)];
int len = cipher.ProcessBytes(RgbEncrypted, 0, RgbEncrypted.Length, C, 0);
len += cipher.DoFinal(C, len);
rgbContent = C;
}
private void CheckTestCase(
ChaCha20Poly1305 encCipher,
ChaCha20Poly1305 decCipher,
string testName,
byte[] SA,
byte[] P,
byte[] C,
byte[] T)
{
byte[] enc = new byte[encCipher.GetOutputSize(P.Length)];
if (SA != null)
{
encCipher.ProcessAadBytes(SA, 0, SA.Length);
}
int len = encCipher.ProcessBytes(P, 0, P.Length, enc, 0);
len += encCipher.DoFinal(enc, len);
if (enc.Length != len)
{
Fail("encryption reported incorrect length: " + testName);
}
byte[] mac = encCipher.GetMac();
byte[] data = new byte[P.Length];
Array.Copy(enc, 0, data, 0, data.Length);
byte[] tail = new byte[enc.Length - P.Length];
Array.Copy(enc, P.Length, tail, 0, tail.Length);
if (!AreEqual(C, data))
{
Fail("incorrect encrypt in: " + testName);
}
if (!AreEqual(T, mac))
{
Fail("getMac() returned wrong mac in: " + testName);
}
if (!AreEqual(T, tail))
{
Fail("stream contained wrong mac in: " + testName);
}
byte[] dec = new byte[decCipher.GetOutputSize(enc.Length)];
if (SA != null)
{
decCipher.ProcessAadBytes(SA, 0, SA.Length);
}
len = decCipher.ProcessBytes(enc, 0, enc.Length, dec, 0);
len += decCipher.DoFinal(dec, len);
mac = decCipher.GetMac();
data = new byte[C.Length];
Array.Copy(dec, 0, data, 0, data.Length);
if (!AreEqual(P, data))
{
Fail("incorrect decrypt in: " + testName);
}
}
private void RandomTest(SecureRandom random)
{
int kLength = 32;
byte[] K = new byte[kLength];
random.NextBytes(K);
int pHead = random.Next(256);
int pLength = random.Next(65536);
int pTail = random.Next(256);
byte[] P = new byte[pHead + pLength + pTail];
random.NextBytes(P);
int aLength = random.Next(256);
byte[] A = new byte[aLength];
random.NextBytes(A);
int saLength = random.Next(256);
byte[] SA = new byte[saLength];
random.NextBytes(SA);
int nonceLength = 12;
byte[] nonce = new byte[nonceLength];
random.NextBytes(nonce);
AeadParameters parameters = new AeadParameters(new KeyParameter(K), 16 * 8, nonce, A);
ChaCha20Poly1305 cipher = InitCipher(true, parameters);
int ctLength = cipher.GetOutputSize(pLength);
byte[] C = new byte[saLength + ctLength];
Array.Copy(SA, 0, C, 0, saLength);
int split = NextInt(random, saLength + 1);
cipher.ProcessAadBytes(C, 0, split);
cipher.ProcessAadBytes(C, split, saLength - split);
int predicted = cipher.GetUpdateOutputSize(pLength);
int len = cipher.ProcessBytes(P, pHead, pLength, C, saLength);
if (predicted != len)
{
Fail("encryption reported incorrect update length in randomised test");
}
len += cipher.DoFinal(C, saLength + len);
if (ctLength != len)
{
Fail("encryption reported incorrect length in randomised test");
}
byte[] encT = cipher.GetMac();
byte[] tail = new byte[ctLength - pLength];
Array.Copy(C, saLength + pLength, tail, 0, tail.Length);
if (!AreEqual(encT, tail))
{
Fail("stream contained wrong mac in randomised test");
}
cipher.Init(false, parameters);
int decPHead = random.Next(256);
int decPLength = cipher.GetOutputSize(ctLength);
int decPTail = random.Next(256);
byte[] decP = new byte[decPHead + decPLength + decPTail];
split = NextInt(random, saLength + 1);
cipher.ProcessAadBytes(C, 0, split);
cipher.ProcessAadBytes(C, split, saLength - split);
predicted = cipher.GetUpdateOutputSize(ctLength);
len = cipher.ProcessBytes(C, saLength, ctLength, decP, decPHead);
if (predicted != len)
{
Fail("decryption reported incorrect update length in randomised test");
}
len += cipher.DoFinal(decP, decPHead + len);
if (!AreEqual(P, pHead, pHead + pLength, decP, decPHead, decPHead + decPLength))
{
Fail("incorrect decrypt in randomised test");
}
byte[] decT = cipher.GetMac();
if (!AreEqual(encT, decT))
{
Fail("decryption produced different mac from encryption");
}
//
// key reuse test
//
cipher.Init(false, AeadTestUtilities.ReuseKey(parameters));
decPHead = random.Next(256);
decPLength = cipher.GetOutputSize(ctLength);
decPTail = random.Next(256);
decP = new byte[decPHead + decPLength + decPTail];
split = NextInt(random, saLength + 1);
cipher.ProcessAadBytes(C, 0, split);
cipher.ProcessAadBytes(C, split, saLength - split);
len = cipher.ProcessBytes(C, saLength, ctLength, decP, decPHead);
len += cipher.DoFinal(decP, decPHead + len);
if (!AreEqual(P, pHead, pHead + pLength, decP, decPHead, decPHead + decPLength))
{
Fail("incorrect decrypt in randomised test");
}
decT = cipher.GetMac();
if (!AreEqual(encT, decT))
{
Fail("decryption produced different mac from encryption");
}
}
private byte[] ChaCha20_Poly1305(CBORObject alg, byte[] K)
{
ChaCha20Poly1305 cipher = new ChaCha20Poly1305();
KeyParameter ContentKey;
int cbitTag = 128;
// The requirements from JWA
// IV is 96 bits
// Authentication tag is 128 bits
// key size is 256 bits
byte[] IV = new byte[96 / 8];
CBORObject cbor = FindAttribute(HeaderKeys.IV);
if (cbor != null)
{
if (cbor.Type != CBORType.ByteString)
{
throw new CoseException("IV is incorrectly formed.");
}
if (cbor.GetByteString().Length > IV.Length)
{
throw new CoseException("IV is too long.");
}
Array.Copy(cbor.GetByteString(), 0, IV, IV.Length - cbor.GetByteString().Length, cbor.GetByteString().Length);
}
else
{
s_PRNG.NextBytes(IV);
AddAttribute(HeaderKeys.IV, CBORObject.FromObject(IV), UNPROTECTED);
}
if (K == null)
{
Debug.Assert(alg.Type == CBORType.Number);
switch ((AlgorithmValuesInt)alg.AsInt32())
{
case AlgorithmValuesInt.ChaCha20_Poly1305:
K = new byte[256 / 8];
cbitTag = 128;
break;
default:
throw new CoseException("Unsupported algorithm: " + alg);
}
s_PRNG.NextBytes(K);
}
// Generate key
ContentKey = new KeyParameter(K);
// Build the object to be hashed
byte[] aad = getAADBytes();
AeadParameters parameters = new AeadParameters(ContentKey, cbitTag, IV, aad);
cipher.Init(true, parameters);
byte[] C = new byte[cipher.GetOutputSize(rgbContent.Length)];
int len = cipher.ProcessBytes(rgbContent, 0, rgbContent.Length, C, 0);
len += cipher.DoFinal(C, len);
RgbEncrypted = C;
return(K);
}
