NewFactory creates a new factory backed by the specified plugin and plugin configuration.

Serve instantiates and serves a concrete Signer instance as a plugin.

SignerName is the name used to identify the plugin backed signer.

FactoryConfig is the plugin factory configuration.

RPCContextSignArgs is exposed entirely to placate `net/rpc`.

RPCInitArgs is exposed entirely to placate `net/rpc`.

RPCLoadArgs is exposed entirely to placate `net/rpc`.

Signer is the interface that must be implemented by all signer plugins.