Article View: sci.crypt
Article #999Re: pgp2.0 - what is an appropriate key length?
From: G.D.Shaw
Date: Sat, 26 Sep 1992 09:43
Date: Sat, 26 Sep 1992 09:43
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In article <1992Sep25.191759.25545@nevada.edu> oliverm@nevada.edu (Moises Oliveira ) writes: > >I keep hearing that RSA uses the product of two big primes to produce a really >big number that is hard to factor. Appearently the diffuculty in factoring >the product of two primes is what makes RSA so hard to crack. > >Now, assume that the actual factoring is trivial by use of some mathematical >method. What good does it do you? Exactly how does having the two prime >factors of some really big number do to help you crack RSA? > >In other words, if see someones public key, how can I find what really >big number they used? And then after I factor it, what whould I do to the >encrypted communications to return it to plain text? > The really big number is the public key. Factor this, and the resulting primes can be trivially combined together to yield the private key. Once you know the private key, you can decrypt the message in the normal way. Graham Shaw (dph3gds@tuda.ncl.ac.uk) Department of Physics, Durham University, England.
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Path: arc1-ca.pugleaf.net!sparky!uunet!mcsun!uknet!newcastle.ac.uk!tuda!dph3gds From: Graham.Shaw@newcastle.ac.uk (G.D.Shaw) Newsgroups: sci.crypt,alt.security,alt.security.pgp Subject: Re: pgp2.0 - what is an appropriate key length? Message-ID: <Bv6Izu.Aoq@newcastle.ac.uk> Date: 26 Sep 92 09:43:06 GMT References: <1992Sep25.191759.25545@nevada.edu> Organization: University of Newcastle upon Tyne, UK NE1 7RU Lines: 22 Nntp-Posting-Host: tuda