Clarify offline usage of sessions and keys and implement implement CryptoSession to support additional crypto use cases. Change-Id: I418ffbb37e3036a2b5eea5a86ac88a5af1a9da07
Change-Id: I06716d2616bbe7efaea6cbf9ba7bf303dfae1650
Change-Id: Ia4cdcbe193d087d33e2ee91e6f5364cbcc237554