Worth a look (authors include D.J. Bernstein):

We describe here MinimaLT, a secure network protocol which delivers protected data on the rst packet of a typical client-server connection. MinimaLT provides substantial protections and is extraordinarily simple to configure and use. In particular, it provides cryptographic authentication of servers and users; encryption of communication; simplicity of protocol, implementation, and conguration; clean IP-address mobility; and DoS protections"