I am a newbie in the security field, so sorry for the naive question.
In my understanding, using symetric encryption, if attacker knows encrypted text, original message, and algorithm means he can calculate the secret pretty easy?
As a prephase:
I am implementing initial security for my small casino, and consider using SSL channel for client - server interactions during the game. What stops me is that I am going to support game observers, who will only track the game state. So if observer becomes attacker, he will effectively know encrypted message, original message and encryption algorithm, effectively leaving nothing out of SSL security.