Here is an alternative to the BSD's cryptodev.
http://carnivore.it/2011/04/23/openssl_-_af_algThe Pro's:
The current OpenSSL supports it, so no patching, compiling.
No non-standard package breakage on an upgrade.
It is in the kernel mainstream, and therefore officially recognised and supported.
It works on the New IT images with recent kernels (GuiPlug) without modifying them.
The Con's:
It is currenty not as fast as cryptodev (hopefully, this will change with maturity).
After playing with this for a couple of days I consider the slower speed only a minor drawback,
whereas the 'offload'ing of the CPU is a significant advantage.