stuart@cs.rochester.edu (01/21/88)
I am somewhat surprised that no-one has mentioned it (perhaps I missed a relevant article or two) but one standard technique for fooling traffic analysis (an element of cryptology but not cryptography) is to insert enciphered "dummy" messages into the traffic. On continuous data streams this can be taken to the limit of sending traffic constantly whether you have "real" traffic or not. A moment's reflection will show you that this technique would be without value if a dummy message could be distinguised from a real message in the enciphered traffic. (Note that on continuous streams you are not going to go to very much trouble to produce dummy messages with the same characteristics as real messages; you'll just send bits and exploit the superiority of your cipher.) Stu Friedberg {ames,cmcl2,rutgers}!rochester!stuart stuart@cs.rochester.edu
henry@utzoo.uucp (Henry Spencer) (01/28/88)
> ... (Note that on continuous streams > you are not going to go to very much trouble to produce dummy messages > with the same characteristics as real messages; you'll just send bits > and exploit the superiority of your cipher.) Ah, but you'd better exercise at least a little bit of cleverness. If the dummy-message content is too predictable, and the opposition finds out about it (remember the standard assumption that the keys can be kept secret but the machinery can't be), you've just handed them a dandy starting point for known-plaintext attacks on your cipher. -- Those who do not understand Unix are | Henry Spencer @ U of Toronto Zoology condemned to reinvent it, poorly. | {allegra,ihnp4,decvax,utai}!utzoo!henry