Article View: sci.crypt
Article #3958Re: how do you tell encrytped data from random data?
From: Michael Mauldin
Date: Wed, 20 Jan 1988 22:52
Date: Wed, 20 Jan 1988 22:52
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In article <275@sysco>, chapman@sco.COM (Brian Chapman Mx321) writes: > Artificialy flat distributions mean that the data is > either a fraud or the encryption method pads with extra > characters. The encryption algorithm might very easily generate purposefully "flat" distributions by a variety of methods. You could switch tables after every block to shuffle "overused" bytes to less commonly used meanings. You can even guarantee perfectly flat counts by not altering the "meaning" of each byte. This turns out to require extra bytes, since once you make a decision that "I've used \035 enough, now", the remaining bytes encode fewer bits. Still, the result would be neither fraudulent nor padded with extra characters (the extra bytes would be "necessary"). If you got a really good encryption algorithm, this would be a pointless add-on feature, but that doesn't mean that seomone else isn't doing it. Michael L. Mauldin (Fuzzy) Department of Computer Science ARPA: Michael.Mauldin@NL.CS.CMU.EDU Carnegie-Mellon University Phone: (412) 268-3065 Pittsburgh, PA 15213-3890
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!rutgers!rochester!PT.CS.CMU.EDU!NL.CS.CMU.EDU!mlm From: mlm@NL.CS.CMU.EDU (Michael Mauldin) Newsgroups: sci.crypt Subject: Re: how do you tell encrytped data from random data? Summary: artificially flat distributions Message-ID: <688@PT.CS.CMU.EDU> Date: 20 Jan 88 22:52:04 GMT References: <660@bucket.UUCP> <275@sysco> <4454@ecsvax.UUCP> Sender: netnews@PT.CS.CMU.EDU Organization: Carnegie-Mellon University, CS/RI Lines: 22