Encryption, decryption and public key RPCs. (#1946)

* Fix up pending receipts details.

* Add support for additional params and registry over RPC.

* Fix tests.

* Add test, additional fix.

Fixes #1932.

* Fix up tests.

* Fix test.

* Fix test.

* Remove unused use.

* Add encryption, decryption and public-key RPCs.

* Remove &