Coda File System

Re: making rpc2 more Secure

From: Jan Harkes <>
Date: Tue, 21 Nov 2000 21:53:39 -0500
On Tue, Nov 21, 2000 at 04:45:33PM +0100, Max Berger wrote:
> Hi,
> we are currently planning on using coda at our university. For reasons of
> simpicicity we want to share the password databse with the unix password.
> I know - the RPC2 protocol ist definitely not secure enough to do so. This
> is why we are currently working on some ideas:
> - Authentication (Are you really my server?) via RSA, probably using the
> ssh-keys.
> - Encryption via blowfish instead of XOR.

I would advise to leverage off existing authentication and encryption
mechanisms provided by SASL and SSL. I don't know how much of SSL is
useable for UDP, but it should at least be able to provide the
encryption routines.

> The whole thing will be available on european servers, no worrying about
> patents or export regulations ;)

Patents are potentially still a worry, even on european servers. The
US export regulations have been opened a lot for opensource software, so
that shouldn't be that much of a problem.

> Are you interested in this solutions? Has anyone worked on anything like
> this yet? And last, but not least: Would these thing be sufficient for
> security?

Yes, we would definitely be interested. Robert Watson worked on
improving RPC2 security, but that work was done a long time ago and
the changes are difficult to merge because RPC2 has seen many internal

Some problems he encountered were,

- Need to add support for variable length RPC2_Encryption keys.
- The binding sequence of RPC2_NewBinding needs to be modified to allow
  for different authentication schemes.
- SFTP timestamps retransmitted packets without decrypting/encrypting,
  breaking SFTP transfers when actual encryption is used.
- SFTP encryption might not even be desireable, because we are looking
  at compression and encryption of container files on the client before
  sending them and keeping them encrypted on the server.
- Integrity of transmitted packets needs to be checked as well

In any case, it is a hard challenge to make a secure RPC2 system, but
that probably makes it all the more interesting.

Received on 2000-11-21 21:53:55