Partial key autonomy

Proposal:

For each party P who so requests,

1. ask party P to generate
   • P_OS_key -- per Firmware security, guards the theft-deterrence code-path through the kernel and initramfs
   • P_FS_key -- see the bottom of OFW's loaddropins.fth; opens the NAND reflash lock.
   • P_LEASE_key -- per Firmware security, opens the activation lock
   • P_OATS_key -- per Theft deterrence protocol and Mass olpc-update, verifies theft-deterrence messages.
2. generate a firmware, initramfs, and olpc-update which contain the public values of these keys.
   • alternately, provide the keys through /ofw and rewrite the initramfs and olpc-update code to read /ofw
3. have OLPC return a signed version of the customized firmware to party P.

By installing the signed customized firmware on a stock machine, party P will be able to autonomously provide builds and activation leases and will be able to execute or modify the theft-deterrence protocol for that machine. Party P may also further delegate these abilities, e.g. with version-2 lease signatures. OLPC will retain responsibility for providing developer keys and firmware updates.