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One time pads and randomness?
by AaronH4321＠aol.com 17 Dec '03

17 Dec '03

Question: I want to use a one time pad pased crypto system. I understand that the randomness of the pad genorator is key to security(other than lossing the keys). What I want to know is if I use a psuedo-RNG that maybe repeats its self every 1000 characters and use it to only encrypt messagase that are 100's of charaters long, will this be a major security risk? Next question: Say I create a 1 million character one time pad that passes all of the randomness tests. It is "truely random". I place it on two computers. Now when these two computers want to send email computer "A" grabs a chunk of the one time pad starting at a random point and encrypts it. It labels the email with the random starting point and sends it to "B". There "B" moves to the random point and begins decryption. During to process both computers mark that section of the OTP used so that they don't retransmit with it. I realize this has a limited amount of messages before it is used up. But would this be secure? Any suggestions, complaints, big gapping holes I missed? Aaron....

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Re: [STATS] Cypherpunks-unedited subscriptions
by i.am.not.a.number＠best.com 17 Dec '03

17 Dec '03

dang! i forgot to change. what's the moderated list being called? which is this one? yikes --- i've been paying attention to somether things. At 08:17 PM 1/17/97 -0800, you wrote: >Total subscribers for: > >Tue 14 Jan: 13 >Wed 15 Jan: 15 >Thu 16 Jan: 13 >Fri 17 Jan: 14 > >Looks like one of two things: >Either nobody wants the unedited list, or, some of the "regular people" >subscribe to the edited list and "flames" list separately, to get both. > > >

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by T. O'Brien 17 Dec '03

17 Dec '03

Your majordomo is malfunctioning. Unsubscribe

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by T. O'Brien 17 Dec '03

17 Dec '03

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by T. O'Brien 17 Dec '03

17 Dec '03

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One time pads, Next question?
by AaronH4321＠aol.com 17 Dec '03

17 Dec '03

Okay, with the intel I have gotten from the responses let me modify and clarify. So, I now know that you can't use a PRNG to create a OTP. If I did have a RNG that could create a "cryptographically" random, million character OTP and I physically loaded the data onto each computer I wanted to communicate with(e.i. group of laptops all loaded at the same location, same time), how cryptographically secure would the data be. I know that physical security would be a nessescary to the system. If I add some type of error checking to make sure someone that knows the plaintext doesn't modify specific characters, an attacker knows what the message is (e.g. "Send $10 to Bob") the message can be altered (to "Send $99 to Bob") even though it is encrypted. So, lets recap. If the keyig material is kept secure, and if the OTP is cryptographically random, and if error checking is implemented then would this be considered a secure(however encumbering it may be) system. Aaron.....

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Re: Keyword scanning/speech recognition
by Lucky Green 17 Dec '03

17 Dec '03

At 03:34 AM 1/19/97, pgut001(a)cs.auckland.ac.nz wrote: >I was talking to someone recently about the feasibilty of keyword-scanning >phone conversations. He thought it was probably still beyond the reach of >current technology, I thought it wasn't. I once met a fellow who's company makes high performance key word scanning and speaker recognition products for use by governmental entities in analyzing voice communications. Unfortunately, I lost his business card. -- Lucky Green <mailto:shamrock@netcom.com> PGP encrypted mail preferred Make your mark in the history of mathematics. Use the spare cycles of your PC/PPC/UNIX box to help find a new prime. http://www.mersenne.org/prime.htm

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RE: One time pads and randomness?
by Blake Coverett 17 Dec '03

17 Dec '03

> I want to use a one time pad pased crypto system. I understand that the > randomness of the pad genorator is key to security(other than lossing the > keys). What I want to know is if I use a psuedo-RNG that maybe repeats its > self every 1000 characters and use it to only encrypt messagase that are > 100's of charaters long, will this be a major security risk? I'm afraid you've fallen into one of the standard traps. A PRNG can *not* make a OTP no matter how you use it. The total amount of entropy in a PRNG is the amount of entropy in the seed you use to key it. All the other bits are directly derived from that seed. A true OTP is completely secure from an information-theory point of view because every byte has a full eight bits of entropy. A PRNG can never have this. Having said all this, it is possible to make a good cipher from a PRNG. RC4, for example, is exactly that and the variable sized key is the seed for the PRNG. It is however very difficult to come up with a good algorithm for that cryptographically sound PRNG and you would be much further ahead to use an existing one rather that trying to roll your own. > Say I create a 1 million character one time pad that passes all of the > randomness tests. It is "truely random". I place it on two computers. Now > when these two computers want to send email computer "A" grabs a chunk of the > one time pad starting at a random point and encrypts it. It labels the email > with the random starting point and sends it to "B". There "B" moves to the > random point and begins decryption. During to process both computers mark > that section of the OTP used so that they don't retransmit with it. I realize > this has a limited amount of messages before it is used up. But would this be > secure? Any suggestions, complaints, big gapping holes I missed? I don't see anything wrong as such, but there is nothing to be gained either. If your random data is real OTP material there is no need to skip to a random byte within it, just start at the beginning and use it in sequence. If your random data is the output of a PRNG like the above then random starting point doesn't buy you much additional security because the entire set of keying material can be recreated from the seed. It may increase the work-factor of searching for the key, but it also imposes the practical problem of keeping all that keying material secure. More importantly don't confuse statistically random with cryptographically random. Just because a bunch of bits passes all the randomness test you can think of doesn't mean it contains 100% entropy. Consider the digits of an irrational number like sqrt(2) or pi, the digits appear statistically random but they can be recreated from just a tiny bit of knowledge. A good litmus test is to ask yourself if there is any way you can reproduce those bits. If there is, they aren't a one time pad. (Of course even if you can't it doesn't mean they are good. :-) regards, -Blake

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Concerned about Pretty Safe Mail for Mac
by nobody＠replay.com 17 Dec '03

17 Dec '03

I'm concerned about the product "Pretty Safe Mail" for the Macintosh, by a company called Highware. I was wondering whether anyone here had tried evaluating it at all. It is a complete PGP implementation (not a front-end). They claim to have licensed some of PRZ's code from PGP. However, as far as I can tell, they are not making any of the source code available. As someone on the comp.security.pgp newsgroups pointed out, writing a wonderful user interface on a PGP trojan horse that either crippled the session key generator or used the session key to leak random portions of secret key primes would be a perfect tactic for a government wishing to penetrate PGP security. With such a great interface, compared to the original PGP, it can't help but become widely used. I realize that without the source code, it's a major hassle, but has anyone looked at Pretty Safe Mail (previously called Safemail) at all for suspicious behavior? For example: 1) non-random session key generation? 2) non-random key pair generation? 3) unnecessary disk access to secret keys? 4) anything else? Any findings, positive or negative, would be appreciated.

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Gilmore and Sandfart suck big dicks
by dlv＠bwalk.dm.com 17 Dec '03

17 Dec '03

Someone wrote to me: >Did you not mean any homo who has ever shaffted Gilmore and Sandy can >write what the fuck they like but straight or intelligent or NORMAL >people will have to be filtered. Yes, that's precisely how Sandfart's moderation will work. Homosexuals like Jason Durbin will continue to post personal attacks on Gilmore's many "enemies", but the victims of the libel will not be able to respond and refute their lies. The concept of "the best response to speech you don't like is more speech" is totally alien to the homosexual subculture on the Internet. These control freaks are into censorship and B&D. >I realize that normal people are few and far between in cypher punks. There may be quite a few normal and knowledgeable people left among the subscribers, but most posters are indeed militant homosexual censors who don't care about crypto except to drop a few "kewl" phrases - like Paul Bradley's infamous "brute-force attack on one-time pads". >I am NOT a cypher-punk and I hope that you do not class me as one, I am >merely interested in cryptography and believe it or not I actually pick >up tips every now and again from the list. I'm sure you're not a "cypher punk" - you're both too smart and too straight. :-) A while back I saw an announcement of a "cypher punks" meating where Jim Bell was explicitly disinvited, and I announced that I don't consider myself a "cypher punk". Jim Bell is a pro-censorship asshole, but I will defend his freedom of speech nevertheless. Occasional tidbits of useful information do still appear on this list. >I am against moderation on the list and I aggree that Gilmug is a lying >cocksucker. Please bear in mind that not everyone on the list is a >"jew-hating" faggot with nothing but shit between their ears. I wholeheartedly agree - however anyone who describes himself as a "cypher punk", after John Gilmore's dishonorable actions, probably is. --- Dr.Dimitri Vulis KOTM Brighton Beach Boardwalk BBS, Forest Hills, N.Y.: +1-718-261-2013, 14.4Kbps

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