Virtual user support

[camelop]

Migrated from: https://github.com/camelop/dds-dev/issues/78

Idea

In the current version of the system, we assume all users are live CoLink servers somewhere with a network address. However, it would be convenient to have users of different types, including

• a smart contract
• a secret sharing committee
• a replicated group (doing the same operation for integrity)

It would be interesting to have some abstraction to support the automatic protocol implementation selection when users are of different types. E.g. The user can forget that the data is stored in a secret shared way and run a protocol without knowing it, while behind the scene, the CoLink server will use different implementations by checking the type of the participant (whether they are real users or secret sharing committee).

Note: This feature might be too advanced to be considered in the current stage.