falk@sun.UUCP (05/12/86)
The subject of censorship of net postings has come up in several newsgroups lately. In particular, the issue of net users censoring each other (by complaining to system administrators) has been discussed. I would be interested in the extent that "official" censorship takes place. For instance, I have heard that there was once a rabid Nazi type on the net who wouldn't shut up and whose views were illegal in some countries (less freedom of speach there than here) and this person's ravings had to be censored from the net before they reached Europe. Another example would be net.crypt. I have the distinct feeling that detailed discussions of DES or RSA are not allowed out of the country. Or for that matter, what if someone tried to post atomic secrets on the net? On the other hand, there is SO MUCH information on the net, that it would be a nightmare to filter the entire thing. How do they do it? I suspect that they have a computer that searches for key words (this is already done with other information traffic in and out of the U.S.). My question is, who are "they", where do they filter the net, how do they do it and how much gets erased? Also, I would like to conduct an experiment. Anybody outside of the U.S. who sees this posting, please send me e-mail so I can get a feel as to how widely this sort of discussion is disseminated. (Note that I've used two keywords, DES & RSA. (oops, I did it again!)). -- -ed falk, sun microsystems
gam@amdahl.UUCP (G A Moffett) (05/12/86)
In article <3660@sun.uucp> falk@sun.uucp (Ed Falk) writes: > Another example would be net.crypt. I have the distinct feeling that > detailed discussions of DES or RSA are not allowed out of the country. Our Corporate legal advisor says that the restrictions against exporting encryption stuff has been lifted. We used to have two UTS's: one with the crypt(3) stuff for domestic customers, and one without export. We no longer distiguish between the two -- we now ship everything to non-USA customers just as to the USA sites. I've already gotten one letter about this, asking me for further confirmation that this is ``true''. First, PLEASE DON'T ASK ME! Talk to *your* companies' legal advisors, or to the Federal Government directly. Second, I am sure we would hear about it from the Federalees if our Corporation were making a mistake .... -- Gordon A. Moffett ...!{ihnp4,seismo,hplabs}!amdahl!gam ~ Ah don't need no diamond ring ~ ~ Ah don't need no Cadillac car! ~ ~ Ah just wanna drink my Lone Star beer ~ ~ Down in the Lightnin' bar! ~ -- [ This does not represent Amdahl Corporation ]
dyer@atari.UUcp (Landon Dyer) (05/12/86)
Is anyone using usenet to exchange encrypted mail? (Especially across
borders to other countries....) Are there /cases/ of this where people
or agencies got upset?
What is the ``backbone policy'' on encrypted messages? [as if there
/could/ be a policy in such a community....]
How do you distinguish --- and clobber --- encrypted messages if you
don't want them going through?
--
Landon Dyer ...{lll-lcc,hoptoad,lll-crg!vecpyr}!atari!dyer
System Administrator For Life,
Atari Corp. Glorious People's New Revolution Collective Computer Center
"If Business is War, then I'm a Prisoner of Business!"sjl@ukc.ac.uk (S.J.Leviseur) (05/14/86)
We are the UK <-> world feed, and we certainly don't censor anything. The normal reason for dropping a group is cost. Each UK site pays about $54 a month for news, and for a lot of sites this causes problem with accountants. The quickest way for a UK site to get the DES crypt code, if they have a source license, is to approach an old site who have pre-embargo copy of Unix. This is perfectly legal since the license DES crypt was issued on is way below System 5.n (my V6 manual thinks it had DES crypt). Source licensed sites are allowed to exchange code provided the code given is from a prior release to the level of the recipients license. This means that it is rather late to start worrying about DES leaking out with Unix now. Why don't the DOD or whoever stop messing around and remove the embargo from the DES crypt, and while they are at it they could release BSD4.3 from embargo as well. Climbs off soapbox, but it's something I feel very strongly about. sean sjl@ukc.ac.uk sjl@ukc.uucp
josh@polaris.UUCP (Josh Knight) (05/15/86)
In article <271@atari.UUcp> dyer@atari.UUcp (Landon Dyer) writes: > >How do you distinguish --- and clobber --- encrypted messages if you >don't want them going through? > It should be very easy to tell encrypted text from plain text. The distribution of characters will be very different. Just for example consider the table below: Plain Encrypted 17095 555 11000 554 7655 553 7329 549 6985 547 6844 541 6272 539 6267 536 5800 535 3973 532 This is the distribution of the number of characters, sorted by the frequency. I.e. the first number in left column is the number of occurrences of the most frequent character in the plain text (blank) and the first number in the right column is the number of occurrences of the most frequent character in the encrypted text (some unprintable thing). The document was input for a text formatter (so period is higher than you might think) but the point is that the encrypted text LOOKS random (has high entropy) while the plain text does not. This particular document has about 126 K characters, so the average number of occurrences per character (the original character set was EBCDIC, so 8 bits are mandatory) is about 500. The minimum number of occurrences for the encrypted text is 439, while for the plain text only the top ranked 88 characters had non-zero counts, the rest being 0. The distribution of character pairs is even more striking. Again, the encrypted text has an almost "flat" distribution. The most frequent pair occurred only 10 times. The encrypted text has MANY more different pairs, about 56 K, than the plain text where there were about 2 K different pairs with the most frequent pair ('e ') occurring 3 K times. Note that detecting and clobbering news items this way will also remove items with totally random content. This would affect some news groups, but the effect might be considered beneficial in any event ;-). The encryption was done by an IBM product, which for the purposes of this discussion uses plain DES. This of course does not change the fact that any opinions expressed or implied are mine and not my employers. -- Josh Knight, IBM T.J. Watson Research josh@ibm.com, josh@yktvmh.bitnet, ...!philabs!polaris!josh
rt@nott-cs.UUCP (05/15/86)
In article <3660@sun.uucp>: > >Also, I would like to conduct an experiment. Anybody outside of the U.S. >who sees this posting, please send me e-mail so I can get a feel as to how >widely this sort of discussion is disseminated. (Note that I've used two >keywords, DES & RSA. (oops, I did it again!)). >-- [Apologies for putting this on net, but mail system wasn't playing] Hi. Well, it managed to get as far as here (Nottingham, UK). Anyway, if they are using keywords to find suspect articles, surely they'd let ones like youre's through? (Assuming they look at anything before they junk it) Roy (Note keywords still in) [There are no opinions in this posting, therefore they cannot coincide with those of my employers]
jim@randvax.UUCP (05/23/86)
In article <527@polaris.UUCP> josh@polaris.UUCP (Josh Knight) writes: > >It should be very easy to tell encrypted text from plain text. The >distribution of characters will be very different. Just for example >consider the table below: > > Plain Encrypted > > 17095 555 > 11000 554 > .... 553 > 5800 535 > 3973 532 Not all kinds of encryption will mess up the single-letter frequencies this well. For example, simple substitution (e.g. the ROT13 Caesar cipher used in net.jokes) has the same single-letter frequency as the underlying language. The Bazeries cipher, which combines simple substitution with permutation, would also have the same single-letter frequency distribution. For these it would be sufficient to note that the high-frequency letters are different from English in the sample. However, you can't even count on that: pure transposition systems will leave the individual letters alone and merely shift their locations, so that the single-letter frequency count will still look like English. For most of my stuff I've found that looking at a measure of digraph frequencies seems to do pretty well in general. I mainly use it to tell whether a [possibly modified] brute force run has finally found the answer -- saves eyeballing a lot of printouts. -- Jim Gillogly {decvax, vortex}!randvax!jim jim@rand-unix.arpa