From: GOTOU Yuuzou <gotoyuzo@...>
Date: 2004-07-02T15:16:02+09:00
Subject: Re: Another Ruby/OpenSSL Patch

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?
-- 
gotoyuzo

require "openssl"

class OpenSSL::PKey::DSA
  def do_sign(data)
    sig = sign(OpenSSL::Digest::DSS1.new, data)
    a1sig = OpenSSL::ASN1.decode(sig)
    sig_r = sprintf("%.40x", a1sig.value[0].value)
    sig_s = sprintf("%.40x", a1sig.value[1].value)
    if sig_r.length > 40 || sig_s.length > 40
      raise OpenSSL::PKey::DSAError, "bad sig size"
    end
    return [sig_r].pack("H*") + [sig_s].pack("H*")
  end

  def do_verify(sig, data)
    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)
  end
end

dsa = OpenSSL::PKey::DSA.new(512)
data = File.read(__FILE__)
sig = dsa.do_sign(data)
p dsa.do_verify(sig, data)