Is SecureBlackbox multithreaded?
The correct term would be "thread-safe", i.e. capable of being called from multiple threads simultaneously.
In SecureBlackbox all classes can be grouped to "containers" and "data processors". Container classes are those used to manage X.509 certificates, OpenPGP keys and SSH keys (note, that only the classes used for management, and not the classes which represent the individual certificates or keys).
Container classes are thread-safe i.e. you can add and delete certificates and keys from multiple threads at the same time.
Data processing classes are not thread-safe. For example, you can't use one instance of ElPGPWriter class to encrypt several files from multiple threads at the same time. If you want to speed-up processing of the data by running several threads, you need to create several instances of ElPGPWriter class and use one instance in one thread. The same applies to other data processing classes.