The Stateless OpenPGP Command-Line Interface

The Stateless OpenPGP Command-Line Interface (or sop) is a specification that encourages OpenPGP implementors to provide a common, relatively simple command-line API for purposes of object security.

This Python module helps implementers build such a CLI from any implementation accessible to the Python interpreter.

It does not provide such an implementation itself -- this is just the scaffolding for the command line, which should make it relatively easy to supply a handful of python functions as methods to a class.

Note that if the user has argcomplete installed, they should also get tab completion in standard shells like bash basically for free.

Example

Here is an example of a minimal command-line tool that just implements the extract_cert() interface, using (imaginary) module foo that has the appropriate

#!/usr/bin/python3
# PYTHON_ARGCOMPLETE_OK
import sop
import foo

class FooSop(sop.StatelessOpenPGP):
    def __init__(self):
        super().__init__(prog='FooPGP', version='0.17')
    # overrides go here...
    def extract_cert(self, key:bytes, armor:bool=True, **kwargs:Namespace) -> bytes:
        self.raise_on_unknown_options(**kwargs)
        return foo.bytes_to_openpgp_key(key).get_certificate(armor=armor)

if __name__ = "__main__":
    foo = FooSop()
    foo.dispatch()

Module Goals

Extensibility

An implementer who wants to extend sop in a simple way (e.g. adding an option to an existing subcommand, or adding a special option) should be able to do so without breaking this interface.

Minimal dependencies

The aim is to only depend on modules from stdlib. We make an exception for optional modules like argcomplete, which can be skipped.

Type-checking

All the code in here should be well-annotated

Self-documenting

Implementers should learn what they need to know from the docstrings, like so:

import sop
help(sop)
help(sop.StatelessOpenPGP)

Semantic Versioning

The major version number will only change when backward-incompatible changes are made.

As long as the major version number is 0, the same holds true for the minor version number.