# joeecc

joeecc is a playground for Elliptic Curve Cryptography in F_{P}. It is
written in pure Python and aims to explain ECC in easy terms. It is neither
written to be performant, nor side-channel resistant nor in any way suited for
productive use at all. Please use it for its intended purpose and for it only.

The rationale behind joeecc is to show a clear and mathematically clean
presentation of the underlying mathematical problems. Most code that is written
arund ECC -- especially code that revolves around Ed25519 and/or Curve25519 is
heavily optimized and in many cases hard to understand. joeecc tries to
present the problems with a high level of abstraction in order to serve as yet
another (different) reference to compare implementations against and in order
to aid understanding of heavily optimized code. All curve arithmetic is
therefore performed in affine space; performance in affine space is lowest, but
having values that directly can be checked against the curve equation makes
understanding everything extremely easy.

## Tutorial

There's a ECC tutorial that I've written which accompanies the pure code. It
can be found at

http://johannes-bauer.com/compsci/ecc/

## Features

- ECDSA demonstration
- ECIES demonstration
- ECDH demonstration
- Elgamal demonstration
- Demonstration how a private key can be recovered from two ECDSA signatures
which reused the same nonce (ECDSA nonce exploit)
- Support for short-formed Weierstrass curves, Montgomery curves and twisted
Edwards curves
- Conversion of domain parameters of twisted Edwards to Montgomery form and
back, conversion of points between Montgomery representation and its
birationally equivalent twisted Edwards counterpart
- Ed25519 and Curve25519 support and support to convert keys between each
other (Curve25519 and Ed25519 are birationally equivalent curves)
- Many testcases to try out your own implementation
- Example of OpenBSD's signify application (generates and verifies Ed25519
signatures, but doesn't support key encryption)
- Clean, well-documented Python3 code