stargrave's blog

Archive for July, 2014

Minimalist simple high performance secure VPN daemon

Wednesday, July 30th, 2014

Several days ago I decided to make an alternative for OpenVPN: GoVPN. OpenVPN uses rather slow HMAC for message authentication and no zero-knowledge password authenticated key exchanges. He is pretty simple, but with not so high security margin and performance.

I wrote already working (but of course with possibly many bugs) daemon on Go programming language. It uses one of the faster crypto algorithms available today and achieves zero-knowledge mutual pre-shared key authenticated key exchange. All derived keys are per-session, so even if PSK is compromised, there is no way to decrypt captured traffic (perfect forward secrecy property).

It does neither interface nor IP-address and routing management: it is the task of underlying OS facilities. And currently it can work with only single client. But I am planning to fix that: so it can be used with many clients simultaneously. Moreover secure remote password can be better choice to allow humans use memorable passwords instead of 256bit keys.

I think that the main comparative advantage is small code size, that can be easily analyzed, audited and fixed. From technical point of overview: it uses Salsa20, Poly1305, Curve25519 and DH-EKE with PSK.