public static void InitializeSession(SessionState sessionState, AliceSignalProtocolParameters parameters)
{
try
{
sessionState.SetSessionVersion(CiphertextMessage.CurrentVersion);
sessionState.SetRemoteIdentityKey(parameters.GetTheirIdentityKey());
sessionState.SetLocalIdentityKey(parameters.GetOurIdentityKey().GetPublicKey());
EcKeyPair sendingRatchetKey = Curve.GenerateKeyPair();
MemoryStream secrets = new MemoryStream();
byte[] discontinuityBytes = GetDiscontinuityBytes();
secrets.Write(discontinuityBytes, 0, discontinuityBytes.Length);
byte[] agree1 = Curve.CalculateAgreement(parameters.GetTheirSignedPreKey(),
parameters.GetOurIdentityKey().GetPrivateKey());
byte[] agree2 = Curve.CalculateAgreement(parameters.GetTheirIdentityKey().GetPublicKey(),
parameters.GetOurBaseKey().GetPrivateKey());
byte[] agree3 = Curve.CalculateAgreement(parameters.GetTheirSignedPreKey(),
parameters.GetOurBaseKey().GetPrivateKey());
secrets.Write(agree1, 0, agree1.Length);
secrets.Write(agree2, 0, agree2.Length);
secrets.Write(agree3, 0, agree3.Length);
if (parameters.GetTheirOneTimePreKey().HasValue)
{
byte[] otAgree = Curve.CalculateAgreement(parameters.GetTheirOneTimePreKey().ForceGetValue(),
parameters.GetOurBaseKey().GetPrivateKey());
secrets.Write(otAgree, 0, otAgree.Length);
}
DerivedKeys derivedKeys = CalculateDerivedKeys(secrets.ToArray());
Pair <RootKey, ChainKey> sendingChain = derivedKeys.GetRootKey().CreateChain(parameters.GetTheirRatchetKey(), sendingRatchetKey);
sessionState.AddReceiverChain(parameters.GetTheirRatchetKey(), derivedKeys.GetChainKey());
sessionState.SetSenderChain(sendingRatchetKey, sendingChain.Second());
sessionState.SetRootKey(sendingChain.First());
}
catch (IOException e)
{
throw new Exception(e.Message);
}
}
