How hard is it to conduct a known plain text attack? My program is sending a very short message (say a 32-bit word) and the plain-text is known (say a boolean value with known padding). I'm using OpenSSL to set up the session for which this message will be sent, so the cipher will be 3DES, RC4, AES, IDEA, or the like. How hard would it be for someone to take an intercepted message and the plain text message and reverse engineer the key? Assume the interceptor knows which cipher is being used.

Thank in advance.

in pseudocode:

boolean val = true;
other sends on same SSL Connection with the same session key.