tree 4d65f0fcb599701f2d3d0e765d68e042d3ae05cd
parent b2ca6630b97c1ad5c80e12da4b069b9c7e25d1f5
author Shawn Willden <swillden@google.com> 1438037910 -0600
committer Shawn Willden <swillden@google.com> 1445022807 -0600

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: 24873723
Change-Id: I740572eb11341fb0659085309da01d5cbcd3854d