Add seal and open streams, and a few basic tests. Define an initial
version of the SymmetricKeyResolver, which TLF pseudonym code will
eventually plug into.
Coverage decreased (-1.01%) to 84.322% when pulling da06e7d3107089bd46c4a9865a88832c7bdd3bd1 on jack/CORE-4787/signcryption into da495ba49a90cfcd390dd90b4049316864f1aa26 on master.
Coverage decreased (-0.9%) to 84.412% when pulling 4a214c235ee0d6a44f08a818301201ba499051e8 on jack/CORE-4787/signcryption into da495ba49a90cfcd390dd90b4049316864f1aa26 on master.
Coverage decreased (-1.2%) to 84.185% when pulling 0838817389dbb5f5f9d5ca2d6aa60cbe5d787987 on jack/CORE-4787/signcryption into da495ba49a90cfcd390dd90b4049316864f1aa26 on master.
Coverage decreased (-1.2%) to 84.145% when pulling e6ba1ec3276a29717e518221eb1a11a692a6a653 on jack/CORE-4787/signcryption into da495ba49a90cfcd390dd90b4049316864f1aa26 on master.
Coverage decreased (-1.2%) to 84.175% when pulling e6eeb092a61670a1b43ee5f795653bf8ca500147 on jack/CORE-4787/signcryption into da495ba49a90cfcd390dd90b4049316864f1aa26 on master.
Add seal and open streams, and a few basic tests. Define an initial version of the SymmetricKeyResolver, which TLF pseudonym code will eventually plug into.
r? @maxtaco @mlsteele