HMAC keys are authorized for exactly one digest.

This is in preparation for enforcing the minimum length of MACs
which in the case of HMAC keys generated or imported by Android
Keystore will be set to the length of the digest for which the
key is authorized.

Bug: 22337277
Change-Id: I0255d5ba184dabfb6b45d8f32ddadeb84ab7fc19
4 files changed