From: Francis Cianfrocca <garbagecat10@...>
Date: 2006-08-12T02:28:20+09:00
Subject: Re: Cryptographic Signatures: Ruby versus OpenSSL

 On 8/11/06, Andy Stewart <ruth_andy@fastmail.fm> wrote:
>
> That's perfect, thank you.
>
> I'll now go and dig through RSA::private_encrypt and RSA::sign and
> see how they differ.
>
> Thank you also to Jan and Robert for your helpful comments.
>
> Kind regards,
> Andy
>
>

RSA#sign is basically a wrapper over EVP_SignInit, EVP_SignUpdate and
EVP_SignFinalize, which are themselves a high-level wrapper over the
actual crypto operations. The EVP_xxx calls do the hashing for you, so
since you're using RSA, you have to specify a digest algorithm.

rsautl -sign is a very dumb piece of code that only encrypts your
plaintext with a private key. You notice in your shell pipeline, you
did the sha digest yourself. That's what I did in the Ruby code I sent
you.

I assume you tested the Ruby output with rsautl -verify and it worked?