At 05:54 PM 2/21/01 -0600, Jim Choate wrote:
There is NO algorithm which will determine if an arbitrary piece of text is encrypted by an arbitrary algorithm. You can tell, at least statistically if a particular piece of arbitrary text ISN'T a particular algorithm or language either. Again, not the same problem.
The problem is to find a reasonable way for a relay to refuse to forward unencrypted messages. So that participants don't accidentally reveal the discussion. *Not* to identify the language or cipher algorithm. *Where* do you get that idea? (Rhetorical, I realize who I'm replying to..) A general and reliable heuristic is to measure entropy. This will of course pass unencrypted compressed files (including possibly jpeg, mpeg, etc.). A more reliable 'cheat' is to look for headers. This can also enforce an additional (and perhaps unwanted) requirement that a certain tool is used. But again, malicious posters will be able to spoof this. ....... "What company did you say you were from, Mr. Hewlett?" ---Walt Disney to Bill Hewlett eetimes 22.01.01 p 32