An Honest and Simple Question.
in [Cryptography]
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From: Mark Murray on 17 Jul 2010 12:16 On 17/07/2010 16:20, adacrypt wrote: > Hi, Your'e getting too far ahead of the posse here - from my point of > view the mathematical core is untouchable and my remit ends there - > the rest is infrastructure management which is outside of my > experience but I have no doubt that there are solutions to every > problem you postulate - trading punches on hypothetical cases is a > ridiculous at this early stage of development - keep on taking the > tablets - cheers - adacrypt It is a very real situation that for me to had over my credit card details to a vendor in a foreign country, I need to do this over an encrypted link that I can trust. If I have to physically visit very such vendor to obtain a copy of the database, then this cryptosystem is no good. Brushing it off as a "management problem" is to miss the point. I could certainly fly to (say) Amazon, but I'd first have to make visits to the airport courier company, the taxicab company and the airline office to get their databases. If I have to do that, why do I need the bloody internet in the first place? No thanks. I'll use DH, RSA, DSA, AES, 3DES for now. Your system may be a crypto curiosity, its not practical. Practical cryptosystems have ways of doing the key exchange WITHOUT having to meet in person. BTW; in the early days of the USA/USSR "hotline" (a teleprinter), there were mutually shared (via the diplomatic channel) tapes of random numbers that were used for the Vernam cipher (OTP). These tapes were the key to the communication, key (pun!) to fending off hostilities and a total pain to manage due to the need for high levels of physical security needed in sharing the key set. In this way it is similar to the PITA that sharing your database would be. The Vernam cipher has the same key distribution problem that your system has (with the advantage that gazillions of random numbers can be stored on optical disks), and it is already provably secure. Coding a Vernam cipher is trivial, verifying its correctness is equally trivial. Its no good for commerce, but to secure superpower emails, it is sufficient, paticularly if the downside involves a mutual exchange of nasty, radioactive, explosive things. M -- Mark "No Nickname" Murray Notable nebbish, extreme generalist.
From: adacrypt on 17 Jul 2010 12:30 On Jul 17, 4:50 pm, adacrypt <austin.oby...(a)hotmail.com> wrote: > On Jul 17, 4:31 pm, Bruce Stephens <bruce+use...(a)cenderis.demon.co.uk> > wrote: > > > > > > > adacrypt <austin.oby...(a)hotmail.com> writes: > > > [...] > > > > It matters nothing to me what your conception of being asymmetric is - > > > I have stated what I understand it to be and I also point out that its > > > is not normal mathematical terminology or even a jargon word in > > > mathematics - all of mathematics and especially Algebra is intensely > > > asymmetric - > > > It's a technical cryptographic term, and you're right to imply that it's > > very recent. The concept didn't (publically) exist before 1976. RSA > > came a little later. > > > > youv'e been conned by a salient piece of spin that enates from the RSA > > > cipher > > > Wrong. The idea predates RSA, and RSA was never the only asymmetric > > system. > > > > - clearly they believed there would never again be even a remote > > > challenge and they way was clear stake out their own publicity > > > goalposts that would last for all time. > > > Nonsense, you're just making that up. RSA was not the only system and > > isn't now. RSA is in no way in competition with any symmetric systems > > and never has been; there was competition with DSA, and still is > > sometimes. > > > [...] > > > > I don't need it - cheers - adacrypt > > > Yes you do. You use it every time you pay for something over the > > internet (it's what ensures that the web server you're communicating > > with is the one it claims to be, as well as being involved in generating > > the session key for confidentiality). Most likely you use it every time > > you check your email or send a usenet article. > > > You don't think you do because you don't understand what it does. > > Hi , > > >Yes you do. You use it every time you pay for something over the > >internet (it's what ensures that the web server you're communicating > >with is the one it claims to be, as well as being involved in generating > >the session key for confidentiality). Most likely you use it every time > >you check your email or send a usenet article. > > Ok , these are latent uses that I clearly don't appreciate but as far > as my interest in the application of mathematics to cipher deisign > goes I rely only on randomness - I take on board what you are saying > but this a tertiary benefit the public evolving from skillful > management that is way over my head - infrasrtucture fallout > orientated maybe ? - regards - adacrypt- Hide quoted text - > > - Show quoted text - PS: I have come to realise that there are mangement-related benefits that are not fully appreciated when one is totally focused on the mathematical application to the cipher core. Dou you mean that whitfield Diffie was ahead of the RSA team (was that why you state 1976 i.e. predating RSA - if not, what other cipher demonstrates asymmetry ?) - he was unable to find an asymmetric cipher himself so he hopped the ball in US academia - the result was the RSA cipher ? - why did he call it asymmetric - I was not a bit impressed with the popular accounts of his so-called 'discovery'. For my information do you know of a previous use of asymmetric algoritms ? Do you think that the percieved benefits of asymmetry wiould carry forward to any other cipher-type that also uses asymmetric mathematics but is secuired by randomness - adacrypt
From: Mark Murray on 17 Jul 2010 12:51 On 17/07/2010 17:30, adacrypt wrote: > Do you think that the percieved benefits of asymmetry wiould carry > forward to any other cipher-type that also uses asymmetric mathematics > but is secuired by randomness - adacrypt DH, DSA and RSA all require high-quality random numbers. M -- Mark "No Nickname" Murray Notable nebbish, extreme generalist.
From: Bruce Stephens on 17 Jul 2010 17:54 adacrypt <austin.obyrne(a)hotmail.com> writes: > On Jul 17, 4:50 pm, adacrypt <austin.oby...(a)hotmail.com> wrote: [...] > Dou you mean that whitfield Diffie was ahead of the RSA team (was that > why you state 1976 i.e. predating RSA - if not, what other cipher > demonstrates asymmetry ?) - he was unable to find an asymmetric cipher > himself so he hopped the ball in US academia - the result was the RSA > cipher ? - why did he call it asymmetric - I was not a bit impressed > with the popular accounts of his so-called 'discovery'. I'm not an expert (and most certainly not an expert in the history) so probably this is a gross oversimplification. Whitfield Diffie and Martin Hellman's 1976 paper presented the possibility of a new kind of cryptography that we now call asymmetric or public key cryptography. They presented a concrete example, now called Diffie Hellman (DH) which is a key agreement protocol: it lets two people openly (without any secret shared information) negotiate a number which only they will know. They also presented a scheme based on DH that's more recognisably a public key cryptosystem though that's not used as far as I know. The paper also outlines authentication schemes that we'd now call digital signatures referencing yet earlier (non-RSA) work. So it describes the three kinds of public key (asymmetric) cryptosystems, even though as far as I know only DH is still used. > For my information do you know of a previous use of asymmetric > algoritms ? The DH paper references earlier work by Leslie Lamport; I've no idea whether that was actually used. Part of the sudden growth of public cryptography was a coincidence of realising how such schemes could be constructed and the availablity of computing power making such schemes practical. A variety of ideas for trapdoor functions that could form public key systsms were proposed (and continue to be) but IIUC basically DH, RSA, DSA, ElGamal, remain. (And the EC variants of DH, DSA, ElGamal.) > Do you think that the percieved benefits of asymmetry wiould carry > forward to any other cipher-type that also uses asymmetric mathematics > but is secuired by randomness - adacrypt The use of all schemes requires randomness. In DH both parties choose a random number, in RSA (if used for encryption) one generates a random session key which is encrypted using the RSA public key, in DSA (a digital signature scheme) one needs a fresh random number to sign anything. (When used for signing, RSA doesn't require randomness, and you don't need randomness for verifying RSA or DSA signatures or for decrypting with RSA.) For all schemes you need randomness to generate keypairs in the first place (well, not DH which doesn't use persistent keys in that way, but you need randomness each time you use DH).
From: Joseph Ashwood on 17 Jul 2010 19:28
"Mark Murray" <w.h.oami(a)example.com> wrote in message news:4c41d75a$0$12167$fa0fcedb(a)news.zen.co.uk... > The Vernam cipher has the same key distribution problem that your > system has (with the advantage that gazillions of random numbers > can be stored on optical disks), and it is already provably secure. Actually adacrypt is the only person who believes his cipher offers perfect secrecy, the rest of us realize that unicity distance is a simple way of proving he believes a lie. Joe |