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28-Jul-2015 |
Shawn Willden <swillden@google.com> |
Do digesting, and sometimes padding, in SW when HW doesnt.
The keymaster1 specification only requires HW modules to implement
SHA256 out of the list of keymaster1 digest modes. That would force
many keys to be software only, and would break legacy scenarios. This
change uses SoftKeymasterDevice to front keymaster modules that don't
implement the full suite of digests, quietly inserting KM_DIGEST_NONE
and KM_PAD_NONE into key generation/import requests when necessary, then
performing the digesting, and sometimes padding, in software, then
delegating crypto operations to the hardware.
This is only done for RSA and EC keys. Software digesting isn't
possible for HMAC or AES-GCM keys.
Note that this is not the complete fix for the bug. Some changes in
keystore are also required, coming in another CL.
Bug: 22529223
Change-Id: I740572eb11341fb0659085309da01d5cbcd3854d
/system/keymaster/rsa_keymaster1_operation.cpp
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