Partial key autonomy: Difference between revisions
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For each party P who so requests, |
For each party P who so requests, |
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# OLPC asks party P to generate and to supply the public portions of these keys: |
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#* P_OS_key -- per [[Firmware security#Summary|Firmware security]], guards the theft-deterrence code-path through the kernel and initramfs |
#* P_OS_key -- per [[Firmware security#Summary|Firmware security]], guards the theft-deterrence code-path through the kernel and initramfs |
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#* P_FS_key -- see the bottom of OFW's [http://openbios.org/viewvc/cpu/x86/pc/olpc/loaddropins.fth?view=markup&root=OpenFirmware loaddropins.fth]; opens the NAND reflash lock. |
#* P_FS_key -- see the bottom of OFW's [http://openbios.org/viewvc/cpu/x86/pc/olpc/loaddropins.fth?view=markup&root=OpenFirmware loaddropins.fth]; opens the NAND reflash lock. |
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#* P_LEASE_key -- per [[Firmware security#Summary|Firmware security]], opens the activation lock |
#* P_LEASE_key -- per [[Firmware security#Summary|Firmware security]], opens the activation lock |
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#* P_OATS_key -- per [[Theft deterrence protocol]] and [[User:Mstone/Commentaries/Mass olpc-update|Mass olpc-update]], verifies theft-deterrence messages. |
#* P_OATS_key -- per [[Theft deterrence protocol]] and [[User:Mstone/Commentaries/Mass olpc-update|Mass olpc-update]], verifies theft-deterrence messages. |
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# OLPC generates a new firmware update key specific to P's customization request named OLPC_P_FW_key, per [[Firmware security#Summary|Firmware security]]. |
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# generate a firmware, initramfs, and olpc-update which contain the public values of these keys. |
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#* alternately, provide the keys through /ofw and rewrite the initramfs and olpc-update code to read /ofw |
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# have OLPC return a signed version of the customized firmware to party P. |
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Then, throughout the future, OLPC may generate and sign firmware containing the public values of these keys. The keys |
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| ⚫ | By installing |
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* OLPC_FW_key |
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* OLPC_DEVELOP_key |
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* and the OLPC_P_FW_key for each party P |
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should be escrowed for safe-keeping should OLPC cease to exist. |
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| ⚫ | By installing these signed customized firmwares on a stock machine, each party P will be able to provide builds and activation leases and will be able to execute or modify the theft-deterrence protocol for that machine autonomously from all other parties Q, including OLPC. Party P may also further delegate these abilities, e.g. with [[Firmware Key and Signature Formats#Version_2|version-2 lease signatures]]. OLPC will retain responsibility for providing developer keys and firmware updates. |
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==== Benefits ==== |
==== Benefits ==== |
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* unless some care is taken, it poses a denial-of-service risk to innocent third-party users of locked machines. |
* unless some care is taken, it poses a denial-of-service risk to innocent third-party users of locked machines. |
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** (people willing to unlock their machines with a devkey or to maintain their own customized firmware suffer little additional risk.) |
** (people willing to unlock their machines with a devkey or to maintain their own customized firmware suffer little additional risk.) |
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==== Open Questions ==== |
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* How do you do firmware updates after people start using customized firmware? |
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Revision as of 23:49, 24 December 2008
Proposal 1
Maintain the firmware and dev-key status quo while permitting everything else to be modified.
For each party P who so requests,
- OLPC asks party P to generate and to supply the public portions of these keys:
- 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.
- OLPC generates a new firmware update key specific to P's customization request named OLPC_P_FW_key, per Firmware security.
Then, throughout the future, OLPC may generate and sign firmware containing the public values of these keys. The keys
- OLPC_FW_key
- OLPC_DEVELOP_key
- and the OLPC_P_FW_key for each party P
should be escrowed for safe-keeping should OLPC cease to exist.
By installing these signed customized firmwares on a stock machine, each party P will be able to provide builds and activation leases and will be able to execute or modify the theft-deterrence protocol for that machine autonomously from all other parties Q, including OLPC. 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.
Benefits
In addition to providing much-requested autonomy who people who want to control all the other locks on their laptops, this proposal preserves the status quo in three important ways:
- OLPC can generate developer keys itself
- Developer keys remain all-powerful for the laptops for which they are generated
- If v2 signature checking is implemented in the firmware, OLPC can delegate its ability to generate developer keys to others on a per-laptop basis
Risks
However, the implementation of the proposal would incur several risks:
- it somewhat complicates the task of making, testing, distributing, and deploying releases.
- unless some care is taken, it poses a denial-of-service risk to innocent third-party users of locked machines.
- (people willing to unlock their machines with a devkey or to maintain their own customized firmware suffer little additional risk.)
Proposal 2
your proposal here...