From: Jamis Buck <jgb3@...>
Date: 2004-07-02T22:04:38+09:00
Subject: Re: Another Ruby/OpenSSL Patch

GOTOU Yuuzou wrote:
> In message <40E46DA4.2010105@email.byu.edu>,
>  `Jamis Buck <jgb3@email.byu.edu>' wrote:
> 
>>I've attached a patch. With the addition of the DSA#do_verify method 
>>that this patch exposes, Net::SSH can now successfully handle ssh-dss 
>>server keys.
> 
> 
> I think these methods can be written with existing library.
> Could you try the attached code?

Thank-you! That works wonderfully. Now... could I bother you for an 
explanation of what the code does? Specifically, the verification code:

         sig_r = sig[0,20].unpack("H*")[0].to_i(16)
         sig_s = sig[20,20].unpack("H*")[0].to_i(16)
         a1sig = OpenSSL::ASN1::Sequence([
            OpenSSL::ASN1::Integer(sig_r),
            OpenSSL::ASN1::Integer(sig_s)
         ])
         return verify(OpenSSL::Digest::DSS1.new, a1sig.to_der, data)

I understand the first two lines, but what is an ASN1::Sequence, and 
what does converting it to a "der" (on the last line) accomplish?

Thanks again!

-- 
Jamis Buck
jgb3@email.byu.edu
http://www.jamisbuck.org/jamis

ruby -ropenssl 
-e'k="01234567";p((c,c.padding,c.iv,c.key=OpenSSL::Cipher::BF.new,0,k,k*2)[0].decrypt.update("1A81803C452C324619D319F980D5B84DBB45FC0FE2BAA045".scan(/../).map{|n|n.to_i(16).chr}.join))'