TNO PET Lab - secure Multi-Party Computation (MPC) - MPyC - Stubs

This package contains stubs to use for type hinting MPyC.

PET Lab

The TNO PET Lab consists of generic software components, procedures, and functionalities developed and maintained on a regular basis to facilitate and aid in the development of PET solutions. The lab is a cross-project initiative allowing us to integrate and reuse previously developed PET functionalities to boost the development of new protocols and solutions.

The package tno.mpc.mpyc.stubs is part of the TNO Python Toolbox.

Limitations in (end-)use: the content of this software package may solely be used for applications that comply with international export control laws. This implementation of cryptographic software has not been audited. Use at your own risk.

Documentation

Documentation of the tno.mpc.mpyc.stubs package can be found here.

Install

Easily install the tno.mpc.mpyc.stubs package using pip:

$ python -m pip install tno.mpc.mpyc.stubs

Note: If you are cloning the repository and wish to edit the source code, be sure to install the package in editable mode:

$ python -m pip install -e 'tno.mpc.mpyc.stubs'

If you wish to run the tests you can use:

$ python -m pip install 'tno.mpc.mpyc.stubs[tests]'

Usage

When installing this package, the package is installed twice under two different names:

• mpyc-stubs
• tno.mpc.mpyc.stubs

The mpyc-stubs installation is named as such by the convention <package>-stubs, which allows static type tooling to easily pick up the additional annotations. If you only use MPyC without defining custom MPyC coroutines (usually decorated by @asyncoro.mpc_coro and asyncoro.mpc_coro_no_pc in the MPyC source code), then this suffices.

The package tno.mpc.mpyc.stubs provides some convenience functions that help you with writing custom, type-checked MPyC coroutines. Most importantly, MPyC's decorator @asyncoro.mpc_coro[_no_pc] uses the type annotations of a function to determine its MPyC returnType. However, this may be undesirable for more complex functions. As such, tno.mpc.mpyc.stubs provides the following top-level import:

• mpc_coro_ignore is a decorator that replaces mpyc.asyncoro.mpc_coro and avoids interference of type annotations with runtime behaviour. The _ignore part emphasizes that it ignores the type annotations at runtime. After stripping the type annotations, the decorator delegates the runtime logic to MPyC.

Additionally, the following top-level imports can be helpful:

• returnType replaces mpyc.asyncoro.returnType or equivalently mpyc.runtime.Runtime.returnType. We encountered various Mypy issues in the past when annotating mpyc.runtime.Runtime.returnType as it is appended to the class with staticmethod() and that did not preserve type overloads. As such, we provide returnType directly with proper type annotations. The function itself delegates behaviour to the MPyC counterpart.
• BaseSecureFloat is a type that represents secure floating point objects. It inherits from mpyc.sectypes.SecureNumber, and we make Mypy believe that both mpyc.sectypes.SecureFloat as well as our own tno.mpc.mpyc.floating_point.SecureFloatingPoint inherit from it. This way, the type annotations that we added will apply to both. If you develop MPyC coroutines that accept both secure floating point types, then you may use this class as a common ancestor.