[automerger skipped] Fixed unchecked key blob access in attestKey
am: 83aa272cae -s ours
am skip reason: change_id I1e84d334bb93ac878b63e15a59c35631f9e6e397 with SHA1 9dff56c52b is in history

Change-Id: I4f89af85b3cb3d2da41a181a1c6a82482d4e7a3f