public Tuple<RootKey, ChainKey> CreateChain(ECPublicKey theirRatchetKey, ECKeyPair ourRatchetKey)
{
byte[] sharedSecret = Curve.CalculateAgreement (theirRatchetKey, ourRatchetKey.PrivateKey);
byte[] derivedSecretBytes = _kdf.DeriveSecrets (sharedSecret, Key, Encoding.UTF8.GetBytes ("WhisperRatchet"), DerivedRootSecrets.SIZE);
var derivedSecrets = new DerivedRootSecrets (derivedSecretBytes);
RootKey newRootKey = new RootKey (_kdf, derivedSecrets.RootKey);
ChainKey newChainKey = new ChainKey (_kdf, derivedSecrets.ChainKey, 0);
return new Tuple<RootKey, ChainKey> (newRootKey, newChainKey);
}
public void TestChainKeyDerivationV2()
{
byte[] seed = {(byte) 0x8a, (byte) 0xb7, (byte) 0x2d, (byte) 0x6f, (byte) 0x4c,
(byte) 0xc5, (byte) 0xac, (byte) 0x0d, (byte) 0x38, (byte) 0x7e,
(byte) 0xaf, (byte) 0x46, (byte) 0x33, (byte) 0x78, (byte) 0xdd,
(byte) 0xb2, (byte) 0x8e, (byte) 0xdd, (byte) 0x07, (byte) 0x38,
(byte) 0x5b, (byte) 0x1c, (byte) 0xb0, (byte) 0x12, (byte) 0x50,
(byte) 0xc7, (byte) 0x15, (byte) 0x98, (byte) 0x2e, (byte) 0x7a,
(byte) 0xd4, (byte) 0x8f};
byte[] messageKey = {(byte) 0x02, (byte) 0xa9, (byte) 0xaa, (byte) 0x6c, (byte) 0x7d,
(byte) 0xbd, (byte) 0x64, (byte) 0xf9, (byte) 0xd3, (byte) 0xaa,
(byte) 0x92, (byte) 0xf9, (byte) 0x2a, (byte) 0x27, (byte) 0x7b,
(byte) 0xf5, (byte) 0x46, (byte) 0x09, (byte) 0xda, (byte) 0xdf,
(byte) 0x0b, (byte) 0x00, (byte) 0x82, (byte) 0x8a, (byte) 0xcf,
(byte) 0xc6, (byte) 0x1e, (byte) 0x3c, (byte) 0x72, (byte) 0x4b,
(byte) 0x84, (byte) 0xa7};
byte[] macKey = {(byte) 0xbf, (byte) 0xbe, (byte) 0x5e, (byte) 0xfb, (byte) 0x60,
(byte) 0x30, (byte) 0x30, (byte) 0x52, (byte) 0x67, (byte) 0x42,
(byte) 0xe3, (byte) 0xee, (byte) 0x89, (byte) 0xc7, (byte) 0x02,
(byte) 0x4e, (byte) 0x88, (byte) 0x4e, (byte) 0x44, (byte) 0x0f,
(byte) 0x1f, (byte) 0xf3, (byte) 0x76, (byte) 0xbb, (byte) 0x23,
(byte) 0x17, (byte) 0xb2, (byte) 0xd6, (byte) 0x4d, (byte) 0xeb,
(byte) 0x7c, (byte) 0x83};
byte[] nextChainKey = {(byte) 0x28, (byte) 0xe8, (byte) 0xf8, (byte) 0xfe, (byte) 0xe5,
(byte) 0x4b, (byte) 0x80, (byte) 0x1e, (byte) 0xef, (byte) 0x7c,
(byte) 0x5c, (byte) 0xfb, (byte) 0x2f, (byte) 0x17, (byte) 0xf3,
(byte) 0x2c, (byte) 0x7b, (byte) 0x33, (byte) 0x44, (byte) 0x85,
(byte) 0xbb, (byte) 0xb7, (byte) 0x0f, (byte) 0xac, (byte) 0x6e,
(byte) 0xc1, (byte) 0x03, (byte) 0x42, (byte) 0xa2, (byte) 0x46,
(byte) 0xd1, (byte) 0x5d};
ChainKey chainKey = new ChainKey(HKDF.CreateFor(2), seed, 0);
Assert.True(ArrayComparer.Compare(chainKey.Key, seed));
Assert.True(ArrayComparer.Compare(chainKey.GetMessageKeys().CipherKey, messageKey));
Assert.True(ArrayComparer.Compare(chainKey.GetMessageKeys().MacKey, macKey));
Assert.True(ArrayComparer.Compare(chainKey.GetNextChainKey().Key, nextChainKey));
Assert.True(chainKey.Index == 0);
Assert.True(chainKey.GetMessageKeys().Counter == 0);
Assert.True(chainKey.GetNextChainKey().Index == 1);
Assert.True(chainKey.GetNextChainKey().GetMessageKeys().Counter == 1);
}
public void SetSenderChainKey(ChainKey senderChainKey)
{
var chainKey = new Chain.ChainKey {
key = senderChainKey.Key,
index = senderChainKey.Index
};
Structure.SenderChain.chainKey = chainKey;
}
public void SetSenderChain(ECKeyPair senderRatchetKeyPair, ChainKey chainKey)
{
var chainKeyStructure = new Chain.ChainKey {
key = chainKey.Key,
index = (UInt32)chainKey.Index
};
var senderChain = new Chain {
SenderRatchetKey = senderRatchetKeyPair.PublicKey.Serialize(),
SenderRatchetKeyPrivate = senderRatchetKeyPair.PrivateKey.Serialize(),
chainKey = chainKeyStructure
};
Structure.SenderChain = senderChain;
}
public void SetReceiverChainKey(ECPublicKey senderEphemeral, ChainKey chainKey)
{
var chainAndIndex = GetReceiverChain(senderEphemeral);
var chain = chainAndIndex.Item1;
var chainKeyStructure = new Chain.ChainKey {
key = chainKey.Key,
index = (UInt32)chainKey.Index
};
chain.chainKey = chainKeyStructure;
}
public ChainKey GetSenderChainKey()
{
var chainKeyStructure = Structure.SenderChain.chainKey;
var cK = new ChainKey(HKDF.CreateFor(GetSessionVersion()),
chainKeyStructure.key,
chainKeyStructure.index);
return cK;
}
public void AddReceiverChain(ECPublicKey senderRatchetKey, ChainKey chainKey)
{
var chainKeyStructure = new Chain.ChainKey {
key = chainKey.Key,
index = (UInt32)chainKey.Index
};
var chain = new Chain {
chainKey = chainKeyStructure,
SenderRatchetKey = senderRatchetKey.Serialize()
};
Structure.ReceiverChains.Add(chain);
if(Structure.ReceiverChains.Count > 5)
{
Structure.ReceiverChains.RemoveAt(0);
}
}
public DerivedKeys(RootKey rootKey, ChainKey chainKey)
{
RootKey = rootKey;
ChainKey = chainKey;
}
private MessageKeys GetOrCreateMessageKeys(SessionState sessionState, ECPublicKey theirEphemeral, ChainKey chainKey, UInt32 counter)
{
if(chainKey.Index > counter)
{
if(sessionState.HasMessageKeys(theirEphemeral, counter))
{
return sessionState.RemoveMessageKeys(theirEphemeral, counter);
}
else
{
throw new DuplicateMessageException("Received message with old counter: " +
chainKey.Index + " , " + counter);
}
}
if(counter - chainKey.Index > 2000)
{
throw new InvalidMessageException("Over 2000 messages into the future!");
}
while(chainKey.Index < counter)
{
MessageKeys messageKeys = chainKey.GetMessageKeys();
sessionState.SetMessageKeys(theirEphemeral, messageKeys);
chainKey = chainKey.GetNextChainKey();
}
sessionState.SetReceiverChainKey(theirEphemeral, chainKey.GetNextChainKey());
return chainKey.GetMessageKeys();
}
