private byte[] Decrypt(SessionRecord sessionRecord, SignalMessage ciphertext)
{
lock (SessionLock)
{
IEnumerator <SessionState> previousStates = sessionRecord.GetPreviousSessionStates().GetEnumerator(); //iterator
LinkedList <Exception> exceptions = new LinkedList <Exception>();
try
{
SessionState sessionState = new SessionState(sessionRecord.GetSessionState());
byte[] plaintext = Decrypt(sessionState, ciphertext);
sessionRecord.SetState(sessionState);
return(plaintext);
}
catch (InvalidMessageException e)
{
exceptions.AddLast(e); // add (java default behavioir addlast)
}
while (previousStates.MoveNext()) //hasNext();
{
try
{
SessionState promotedState = new SessionState(previousStates.Current); //.next()
byte[] plaintext = Decrypt(promotedState, ciphertext);
sessionRecord.GetPreviousSessionStates().Remove(previousStates.Current); // previousStates.remove()
sessionRecord.PromoteState(promotedState);
return(plaintext);
}
catch (InvalidMessageException e)
{
exceptions.AddLast(e);
}
}
throw new InvalidMessageException("No valid sessions.", exceptions);
}
}
private byte[] Decrypt(SessionRecord sessionRecord, WhisperMessage ciphertext)
{
lock (SESSION_LOCK)
{
IEnumerator <SessionState> previousStates = sessionRecord.GetPreviousSessionStates().GetEnumerator();
LinkedList <Exception> exceptions = new LinkedList <Exception>();
try
{
SessionState sessionState = new SessionState(sessionRecord.GetSessionState());
byte[] plaintext = Decrypt(sessionState, ciphertext);
sessionRecord.SetState(sessionState);
return(plaintext);
}
catch (InvalidMessageException e)
{
exceptions.AddLast(e);
}
while (previousStates.MoveNext())
{
try
{
SessionState promotedState = new SessionState(previousStates.Current);
byte[] plaintext = Decrypt(promotedState, ciphertext);
sessionRecord.GetPreviousSessionStates().Remove(previousStates.Current);
sessionRecord.PromoteState(promotedState);
return(plaintext);
}
catch (InvalidMessageException e)
{
exceptions.AddLast(e);
}
}
throw new InvalidMessageException("No valid sessions.", exceptions);
}
}