My apologies in advance if my question seems a little unprofessional... I am not much of a developer after all.
As part of my university project I need to develop a program that will listen on the network and tell whether the traffic is encrypted or not? What's important is only to know if the traffic coming to a network end is encrypted and it's not really important to know the type and the algorithm of the encryption.
I really have no clue where to begin. I'd appreciate it if anyone could give me some clues on what to look for.
Thanks in advance...
Although the answer of GregS is of course correct, the best way to distinquish encrypted text is to look at the protocol used by the application. For instance, if browsers encrypt anything, it's probably done by using SSL. Remote terminals use SSH.
Although the cipher text is mostly looking as random bytes, you can probably distinquish the encryption protocols. If this is enough depends on your use case. As a first step, many protocols use a specific server port by default; this can be used as a heuristic so you can check the most common protocols for that port first.