You can change the configuration of a backend engine, and thus change the executable program and configuration directory to be used. You can make these changes the default or set them for some contexts individually.
gpgme_set_engine_info changes the default
configuration of the crypto engine implementing the protocol
file_name is the file name of the executable program
implementing this protocol, and home_dir is the directory name
of the configuration directory for this crypto engine. If
NULL, the engine’s default will be used.
The new defaults are not applied to already created GPGME contexts.
This function returns the error code
successful, or an eror code on failure.
gpgme_ctx_set_engine_info can be used to change the engine
configuration per context. See Crypto Engine.