於 四，2013-09-26 於 10:19 +0800，joeyli 提到：
於 三，2013-09-25 於 17:25 -0400，Alan Stern 提到：
On Wed, 25 Sep 2013, David Howells wrote:
I have pushed some keyrings patches that will likely affect this to:
http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=key...
I intend to ask James to pull these into his next branch. If he's happy to do so, I can look at pulling at least your asymmetric keys patch on top of them.
This suggests a point that I raised at the Linux Plumbers conference:
Why are asymmetric keys used for verifying the hibernation image? It seems that a symmetric key would work just as well. And it would be a lot quicker to generate, because it wouldn't need any high-precision integer computations.
Alan Stern
Per my understood, it's like add salt to snapshot when generate signature, then remove the salt when store the snapshot to swap. (or pass snapshot to userland).
Let me explain the symmetric key solution base on my understand:
+ EFI stub kernel generate a hash value from a random seed, then store it to EFi boot varaible. It should protected by UEFI secure boot environment.
+ When hibernate launched: - Kernel create the snapshot image of memory. It's included the random hash value(salt) that generated in EFI stub stage. - Then kernel hash the snapshot image, put the hash to snapshot header, just like current asymmetric keys solution. - Kernel erase the salt in snapshot image before it go to swap or pass to userspace tool.
+ When hibernate resume: - Kernel or userspace tool load the snapshot(without salt) from swap to temporary memory space. - Kernel fill the salt back to snapshot image in memory, hash it. - Kernel compare the hash with the hash that put in snapshot header. - Verification done! The follow-up action as current solution.
Please current me if I missed anything.
Thanks a lot! Joey Lee
For the symmetric key solution, I will try HMAC (Hash Message Authentication Code). It's already used in networking, hope the performance is not too bad to a big image. Thanks Joey Lee -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org