[strongSwan] Good information on adding custom ESP encryption

[Yeagley, Josiah]

Martin, 

   Thank you very much for these links and the information. I have found them very useful and they will make a great example on how to do this. I appreciate it.

Regards,

~Josiah s. Yeagley


-----Original Message-----
From: Martin Willi [mailto:martin at strongswan.org] 
Sent: Saturday, April 09, 2016 4:15 AM
To: Yeagley, Josiah (U.S. Person) <jyeagley at harris.com>
Cc: users at lists.strongswan.org
Subject: Re: [strongSwan] Good information on adding custom ESP encryption

Hi,

> I believe the only real way to do this is via a kernel module using 
> the CrytpoAPI. It then has to be registered with the OS and 
> strongStwan and can then be used by specifying esp=<name you gave it>


Yes, that is correct. For an example you may take a look at the patchset that implements the ChaCha20Poly1305 algorithm [1]. It exposes an AEAD to IPsec, but the mechanics are very similar if you have separate encryption/integrity algorithms. The CryptoAPI for AEAD has slightly changed since then, so better have a look at the current implementation as well.
 Patch 9 in that series then exposes the implemented algorithm to IPsec.
In strongSwan you'll have to add a proposal keyword, an algorithm identifier for the IKE exchange, and map that identifier to the kernel algorithm name you have chosen, see [2].

Regards
Martin

[1]https://www.spinics.net/lists/linux-crypto/msg15123.html
[2]https://git.strongswan.org/?p=strongswan.git;a=commitdiff;h=405c5dcd