PyGLOME

This is not an officially supported Google product.

This repository contains a Python implementation for the GLOME protocol. You can find the library in the folder pyglome. The test files can be found in the test folder.

Python API

Requirements

• Python >= 3.6
• pyca/cryptography >= 2.5

Example

We provide a brief example of use. In order for Alice and Bob to communicate, the first step would be to generate some new keys:

import pyglome

alice_keys = pyglome.generate_keys()
bob_keys = pyglome.generate_keys()

Suppose that Alice knows Bob's public_key and wants to send Bob the message msg and no other message have been shared before. Alice will need to:

glome = pyglome.Glome(bob_keys.public, alice_keys.private)
first_tag = glome.tag(msg, counter=0)

And Alice will send Bob both msg, first_tag as well as Alice's public key. On Bob's end he will need to do the following:

glome = pyglome.Glome(alice_keys.public, bob_keys.private)
try:
    glome.check(first_tag, msg, counter=0)
except pyglome.TagCheckError as tag_error:
    ## Handle the exception.
## do what you have to do

Key generation.

Should you want to use a preexisting key, it should match the format X25519Private/PublicKey provided in pyca/cryptography. Such a key can be easily read from a bytes object as follows:

from cryptography.hazmat.primitives.asymmetric import x25519
my_private_key = x25519.X25519PrivateKey.from_private_bytes(private_key_bytes)
my_public_key = x25519.X25519PublicKey.from_private_bytes(public_key_bytes)

We provide a key generation function generate_keys that uses these methods to create a new key pair from os.urandom bytes.

Documentation

For more information see the in-code documentation.

Test

In the test folder we have scripts that implement test classes based on unittest. To run all tests use:

python -m test

from this directory. If you only want to execute a particular test module, then run:

python -m test.my_module_name

where my_module_name is the name of the test module to be executed (the name of the file without the .py).