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Issue metadata

Status: Available
Owner: ----
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Chrome
Pri: 3
Type: Bug



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Consider migrating dm_verity to SHA256

Project Member Reported by mnissler@chromium.org, May 9 2017

Issue description

SHA1 is at its end of life, so we should seriously consider to switch dm_verity as used for verified boot to more modern hash algorithm, e.g. SHA256 or SHA512.

Before we do so, we should run a few measurements on intel and arm devices to see whether there's any adverse impact on boot timings.

In terms of changes required, we'll probably be OK with build time changes since the device mapper table that specifies the hash algorithm is passed in the kernel command line.
 
Here's a CL that changes the build scripts to use sha256: https://www.chromium.org/Home/chromium-security/security-sheriff

The resulting image boots fine and the dm table states sha256 as the algorithm, but I haven't done any further verification or (performance) testing.
NextAction: 2017-05-18
Wrong link?
The NextAction date has arrived: 2017-05-18
Labels: -Pri-2 Pri-3
Owner: mnissler@chromium.org
Status: Started (was: Available)
Correct link is this: https://chromium-review.googlesource.com/c/503032/

I'll see whether I can push this forward as a side project. If anyone feels this should receive more attention, feel free to grab the bug and run with it.

Comment 5 by vapier@chromium.org, May 22 2017

should we make sure CONFIG_CRYPTO_SHA256_SSSE3 is turned on ?
NextAction: 2017-05-30
Enabling the right crypto kernel config options is a good point. I'll take this into account when measuring performance.
The NextAction date has arrived: 2017-05-30
NextAction: ----
Busy with more important stuff. Since this is Pri-3 anyways, I'll drop the NextAction field for now.
Came across another use of SHA1 in the recovery installer, filed a separate bug for that: https://bugs.chromium.org/p/chromium/issues/detail?id=734968
Owner: ----
Status: Available (was: Started)
Relinquising ownership for now given that I'm busy with other stuff.
Labels: Hotlist-GoodFirstBug
Would we consider this a "good first bug"?
Cc: allenwebb@chromium.org

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