py-uniformdh - OpenSSL based UniformDH

Yawning Angel (yawning at schwanenlied dot me)

What?

This is a OpenSSL based UniformDH implementation for obfs3/ScrambleSuit. It is a drop-in replacement for obfsproxy/transports/obfs3_dh.py

Usage

import uniformdh

my_keypair = uniformdh.UniformDH()
my_public = my_keypair.get_public()

# Get the other public key

shared_secret = my_keypair.get_secret(their_public)

Implementation notes

• This uses OpenSSL.
• This uses C.
• It matches the gmpy based implementation in performance.
• Because it uses OpenSSL's DH code, the mod exp operation is blinded.
• It properly removes the private keys from the heap. Though that's sort of fighting for a lost cause since the shared secret is passed back to Python.
• Because no official test vectors for UniformDH exist, I made some.