January 1993 - cypherpunks-legacy

Re: Computerized OTP (was 5th AMENDMENT & DECRYPTION)
by Marc.Ringuette＠GS80.SP.CS.CMU.EDU 27 Jan '93

27 Jan '93

Thug writes, > The other possibility is to find a truly random RF source that has all > the properties you want, the more important being that the >average< > length of a homogenous bit run (0's or 1's) is around 4 or 5 bits. "All the properties you want?" What you want is random, and nothing else! Random isn't "average bit runs of 4 or 5 bits". It isn't "nice white noise". It is TRULY RANDOM! You need to understand that the absolutely critical property for a one time pad bit-stream to have is this: given all previous bits seen, the probability that the next bit seen will be zero or one is exactly 0.5. What you need is a method for converting a biased random number stream (say, one where after a run of zeroes, another zero has high probability) into an unbiased one where the probability of the next bit being zero is exactly 0.5. Truncating runs to length 5 is an attempt at this, but a VERY BAD and cryptographically useless attempt. Does anybody remember a good recipe for converting a biased RNG into an unbiased one? I can't think of one off the top of my head, and that's what Thug's friend seems to need. This has been discussed at length in the literature. -- Marc Ringuette (mnr(a)cs.cmu.edu)

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5th Amendment and keys
by strat＠intercon.com 27 Jan '93

27 Jan '93

It might be worth pinging Mike Godwin for a summary of his current assessment. I was at a meeting with him over the weekend, and he said he's slowly growing more optimistic with regard to this very issue, as a result of some precedents he found. He'd probably be honored to know that a whole list was hanging on his every word. :-) --Strat

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[veritas!u.washington.edu!news@markv.com: ]
by Jay Prime Positive 27 Jan '93

27 Jan '93

From: jpp@hermix To: cypherpunks(a)toad.com Subject: [veritas!u.washington.edu!news(a)markv.com: ] Interesting message I recieved... Twice... j'

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weak point of PGP implementation
by The Phantom 27 Jan '93

27 Jan '93

tcmay says: ---- With strong crypto, e.g., with 300 decimal digit moduli, the "costs" of decryption by brute force could easily exceed the GNP/GDP of the U.S. ... bagged" the house, perhaps a simple pass phrase was used in lieu of memorizing 300 digits, and so on. ---- I've been wondering about this. It seems as though the weak point of PGP is one of three possible things: 1) RSA key length (a key length of 10 digits might be a good target, but noone using pgp uses anything so absurdly small, so this can be all but ruled out barring any huge jumps in factoring .. 2) 'conventional cryptography' used for encoding the secring.pgp files, etc. What crypto, exactly, is used? How strong is it? If the NSA knocked on the door and demanded your computer, would it try to crack your key, or would it go directly for the secring.pgp file? 3) length/triviality of pass phrase. This is, I would think, the weakest point mentioned yet. How long does the pass phrase have to be until this point becomes as secure as the weaker of the above two? If all bits of your passphrase were random, how long would an exhaustive search take? matt Matt Thomlinson University of Washington, Seattle, Washington. Internet: phantom(a)u.washington.edu phone: (206) 528-5732 PGP 2.0 key availaible via email or finger phantom(a)hardy.u.washington.edu

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Coupled programs and security by obfuscation
by mjr＠netcom.com 27 Jan '93

27 Jan '93

**** Pat Farrel <pfarrell(a)cs.gmu.edu> writes >I expect that current terminal/menu based BBSes will disapear >once folks realize how much better easier, faster, and all >around better programs that use computers as computers work. I hope not... At least not until the BBS operators and writers agree on some standardized API so people like me and other third parties can write PC based interfaces in a language of our choice. The problem with current "coupled systems" (for example the Coconet BBS software) is that they all rely on proprietary interface programs on the PC. If I communicate with 10 BBS systems (large or small), I must have 10 different communications programs... No thanks... Also keep in mind that much of the value of these systems comes from their availability to the widest possible audience. There are people in many parts of the world who still have nothing better then 1970's style glass tty's and even paper-output type terminals! ****** Back on the issue of privacy and anonymity, I don't understand the lure of all these schemes for hiding mail paths, etc. If encrypted messages pass through one aliaser, and get decrypted (and aliased again) on another machine, you are protected. The machine that knows who you are can't read your material, and the machine that can read you doesn't know who you are. Any further obfuscation adds little (IMHO) to your security. Revelation of your identity (in either case) depends on collusion between system administrators on the different hosts. True this might be even less likely where 3 or more hosts are involved, but how much less so? If some agency is powerful enough to force two systems in different parts of the world (and the net) to reveal what they know about you, the chances are they can force three or four, etc. matthew rapaport Philosopher/Programmer At Large KD6KVH mjr(a)netcom.com 70371.255(a)compuserve.com

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Re: Computerized OTP (was 5th AMENDMENT & DECRYPTION)
by Marc.Ringuette＠GS80.SP.CS.CMU.EDU 27 Jan '93

27 Jan '93

thug(a)phantom.com (Murdering Thug) writes, > A person I know is working on a computerized version of the OTP that > extracts a truly random stream of bits from TV/RF static and massages it > using a DSP to be highly variable (e.g.: no runs of 0's or 1's longer than > 5 bits). Cool! You've managed to weaken the one time pad enough for someone to crack it! [ I can collect statistics on the plaintext based on the fact that if five zeroes occur in the OTP then the next bit is constrained to be one. Of course, I don't have complete access to the OTP, but it's an extremely useful statitistical foot-in-the-door. ] This failure occurred because your friend tried to create a number sequence that is somehow "more random than random". Such a sequence is, by definition, weak. -- Marc Ringuette (mnr(a)cs.cmu.edu)

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5th AMENDMENT & DECRYPTION
by John.Nieder＠f33.n125.z1.FIDONET.ORG 27 Jan '93

27 Jan '93

from: john.nieder(a)f33.n125.z1.fidonet.org > In a recent message, Murdering Thug said: > | The Fifth Ammendment is the tastiest one of all when it comes to > | encryption. By pleading the Fifth, you do not have to decrypt anything > | for the prosecution. The Fifth Ammendment gives you the right not to > | testify or provide evidence that would incriminate you. Providing a > | key to decrypt your hard disk would incriminate you, and you don't > | have to do it. I should like to see the body of case law on which this opinion is based, if any. . Recently this question came up in another forum on encryption & an "authority" on communications law claimed the probable scenario would be that the arresting agency would have the encrypted material decrypted by a competent government or academic agency & the costs of said decryption would eventually be recovered from the defendant through civil suits, presuming the defendant had sufficient assets. It is my memory of the thread that he claimed this had been done in previous cases. JN ... Gun control: It ain't about guns, it's about *control*. --- Blue Wave/Opus v2.12 [NR] -- John Nieder - via FidoNet node 1:125/555 UUCP - ...!uunet!hoptoad!kumr!fidogate!33!John.Nieder INTERNET - John.Nieder(a)f33.n125.z1.FIDONET.ORG

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Re: Rational PC mail , was Re: PGP on BBS
by jim＠tadpole.com 27 Jan '93

27 Jan '93

> From pfarrell(a)cs.gmu.edu Tue Jan 26 12:28:05 1993 > > While serial ports do lose characters, especially if you don't have > a 16550afn serial chip, I don't see this as a major hassle. In a pure > DOS space, you really arn't likely to lose the characters, and this > is the initial space of NUpop. With Windows, you have to learn to play > with the priorities to make it work well, or get one of the intellegent > serial driver DLLs that make it transparent. Let me try to put it another way. The higher you drive the DTE rate, the more likely you are to loose characters. At the same time, you start to care less about the (small) protocol overheads involved. > It is possible that the authors of the NUpop document don't worry too > much about single character dropouts. There is plenty of redundancy in > english. PGP will complain, but I can see retransmitting a message > half a dozen times to get it thru cleanly will lose. But if characters change during transmit, how can you tell that the message wasn't altered by some agent other than the device/driver? Further, if it happens only occasionally, won't you react with mistrust of the original message? "Hey, this message doesn't check with the author's key!" If it happens a lot, aren't you more likely to say, "Well, he must have meant $10,000, not $1000, the serial port must be loosing again." rather than resending some number of times? > I never allow my private key anywhere near a serial port. The public keys > are checksummed, so it is easy to see that a character is wrong. > I'd love to be able to use CSLIP. We (a bunch of folks on this campus) have > just convinced the admin to allow POP services. It will take a while before > we can convince them to allow SLIP, CSLIP, and PPP. The older I get, the more I understand, "Power to the people." Cheers, Jim

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withdraw
by Vincent Dileonardo 27 Jan '93

27 Jan '93

I would like to request that I be removed from your mailing list as soon as possible. Thank you. Vinnie DiLeonardo

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Re: Computerized OTP (was 5th AMENDMENT & DECRYPTION)
by pmetzger＠shearson.com 27 Jan '93

27 Jan '93

> From: thug(a)phantom.com (Murdering Thug) > Since none of us have ever been inside the NSA, we cannot > underestimate > their power and resources. For all we know they may have 500 Intel > Delta > supercomputers linked together, each having 65,536 i860-XP/50mhz > chips. > We really don't know what kind of iron they possess. Thus we can't > assume > that they can't factor extremely large numbers easily. Mr. Thug doesn't seem to understand the issue here. Your fear should be that the NSA knows something about number theory we don't, not that they possess a huge number of supercomputers. Consider that we believe the factoring problem to be exponential in the number of digits. That means that doubling the number of digits doesn't double the size of the problem -- it makes it far, far, far worse. Indeed, I suspect that it could be shown that using a key of only a few thousand digits, barring a change in factoring algorithm there would be no way to factor the number in the lifetime of the universe even were all the matter and energy in the universe given over to the factoring problem. There are problems that are known to be that size, by the way -- such as trying to do a complete search on the game tree for chess. So, if you are worried that the NSA might have 10,000 times the resources you suspected, you can just add a few more digits on to your key and defeat that possibility. Myself, I always use a key thats as long as possible to be safe, but I think that paranoia about their HARDWARE is wholely misplaced. The thing to be paranoid about is that they know something about factoring algorithms that we do not. Perry

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