Generating RSA pairs

[Igor de Oliveira Couto]

On 03/05/2013, at 10:38 AM, Dr. Hawkins <dochawk at gmail.com> wrote:

> That's a good point.
> 
> However, I only need a random number once ever per customer; it's to
> encrypt their license keys & privileges.

In a licensing situation, usually the software developer will hold the private key, and will distribute the public key with the software. The public key can then be used the verify the contents and authenticity of the license file. In that scenario, the only public/private key pair you would need to generate would be your own. :-)

> [...] The issue is how to turn the random number, from whatever source, into an
> RSA pair.  I didn't see any way from the openssl man page to feed it a
> random number; it seems to rely on the system.

In your terminal, try "man genrsa". This is the sub-module within openssl that generates rsa key pairs, and it usually has its own man entry. You will see that it takes a -rand parameter, which is a file with random binary data, which is what you use to seed the generator.

> This part only needs to run under unix; there isn't a chance that I'd be
> running a server under windows . . . (my son in law is less than pleased
> that I won't even allow windows machines on my home network . . .)

Wise, very wise... ;-)

I hope this helps!

Kind regards,

--
Igor Couto
Sydney, Australia