On Sat, Oct 4, 2008 at 7:27 PM, Mike -- EMAIL IGNORED <[EMAIL PROTECTED]> wrote: > On Sat, 04 Oct 2008 18:20:45 -0700, David Schwartz wrote: > > [...] > >> http://en.wikipedia.org/wiki/RSA >> >> In the section "Operation", the first set of 5 steps beginning with >> "Choose two distinct large random prime numbers p and q" documents the >> process of computing an RSA private key. >> >> If you want example code, the OpenSSL distribution includes that in >> appls/genrsa.c. >> >> DS >> > [...] > > I have been looking at the article you mention, and it > does not provide enough detail. In particular, in the > terms of that article, it indicates that Eve could > compute d if she could factor n to obtain p and q. I > assume that if I knew how d is computed, I would see > why this is so. I do not see this in the article, > and I have not been able to goog it. > > Mike.
Factoring 'n' is what is called a "hard problem", and is the problem upon which the security of the RSA algorithm rests. If Eve obtains p and q, she has the ability to recreate the private key, and thus the constraint made (that only one entity has the private key) is violated. To figure out how to compute d, look at the notes in the aforementioned wikipedia article for steps 4 and 5 (they reference the Extended Euclidean Algorithm and Modular Arithmetic). Note that if Eve has p and q, then she can go through the same steps as the original key generator. -Kyle H ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List [email protected] Automated List Manager [EMAIL PROTECTED]
