http://microcodes.sourceforge.net/
There you can find a PDF reviewing the microcode update feature. Apparently the updates from Intel are 2048 bytes long overall, and have a 4-byte checksum, and are "encrypted" using some kind of mechanism on the processor. Since they don't (to my knowledge) express any instructions for doing encryption natively, they likely don't have any just for the microcode update, so it *should* be something simple, relying more on obscurity and the small size of the updates than cryptographic strength. Still, most of the details remain unknown to all but about ten guys in Intel. Writing your own "jump to ring zero" instruction is left as an exercise to the reader. -- "Curiousity killed the cat, but for a while I was a suspect" -- Steven Wright Security Guru for Hire http://www.lightconsulting.com/~travis/ -><- GPG fingerprint: 9D3F 395A DAC5 5CCC 9066 151D 0A6B 4098 0C55 1484 --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]