bert hubert <ahu@ds9a.nl>

THIS PROJECT HAS BEEN DEPRECATED - REAL IPSEC here

Simple Packet Signing for Linux

SPS allows you to sign and encrypt your IP traffic with minimal configuration. This implementation strives for security, simplicity and robustness. SPS itself adds 'portability' to that goal.

The Linux version is completely modular and requires no patches to either iptables or the kernel. It should work on all 2.4 kernels!

We currently plan releasing implementations for:

We welcome other implementations, please drop us a line if you are considering joining in!

Why Simple Packet Signing

Simplicity, simplicity, simplicity. Our goal is a secure internet. We can achieve that with secure protocols, but we must also make sure that those protocols are then used! The full Linux configuration for signed & authenticated packets between networks A and B: 
A:~# iptables -t mangle -A OUTPUT -d B -j SIGN --sign-with-secret=s3cr3t
B:~# iptables -t mangle -A PREROUTING -m verify --verify-secret=s3cr3t -j UNSIGN
.. And vice-versa.
Our motto is 'Simple things should be easy, hard things should be possible'. If you want to sign with full public/private semantics, it will be possible. Using extra iptables commands, you can give or withhold finegrained access to your network.
One extra boon of this is that it will work over dynamic ip address - from now on you can easily trust your laptop's packets, wherever the come from.

Motivation & PLAN

Current very rough PLAN is here. *Very* open to further discussion, taking place on the netfilter-devel list. See the Netfilter page for information on how to subscribe. Also explains why this is not ipsec, why this is not a tunnel and why simple ssh does not cut it.

News

2001-09-09 Lots of thinking going on. Encryption turns out, like signing, to be harder than I thought. SPS has been a real learning experience so far! I think we will be using 'Cipher Block Chaining' mode, CBC, with a random but specified IV. A lot of people have been telling me that 'encryption is easy, use OpenSSL'. Sorry, no, encryption is *never* easy. Even with a quality library. In the words of Zedz's Alex de Joode, 'Cryptography is easy (...) to fuck up'.

Besides crypto, NAT has also been an issue. It is vital that SPS signs only *after* performing NAT, or is otherwise aware of the ultimate source address. It is not yet clear how this fits in with iptables. Brad Chapman has patches which might help - we're still pondering.

2001-08-29 YES! It functions! Some renaming needs to be done and a lot of cleaning up, but the syntax described above WORKS! Replace UNSIGN by STRIPSPS and it will function!
2001-08-28I'm looking for ipsec minded people who can tell me if it is easy to implement the simplicity mentioned above using AH - it would be great to get into a best of both worlds situation where we have the non-intrusiveness of the current SPS Linux code while following a standard, too.
2001-08-26Added some relevant links and a Thanks To section. Decided to concentrate on symmetric encryption/signing first, asymmetric is very slow. Algorithms will probably be SHA-1 HMAC (RFC 2104) and Blowfish. Asymmetric needs more thinking.
2001-08-26Added SPEC file, outlining some ideas about the protocol

Code

Most up to date is CVS.

State

You can encapsulate packets, and sign them with a secret. No public key yet. Also no support for multiple algorithms. Only SHA-1 according to RFC 2104. Conclusions so far: More in the TODO file.

Links to relevant pages and projects

Thanks to

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