noknow 0.2.0

Non-Interactive Zero-Knowledge Proof Implementation in Pure Python

NoKnow

Zero-Knowledge Proof implementation in pure python

_{Built with ❤︎ by Austin Archer :)}

Table of Contents

• Credits
• Purpose
• How it Works
• API
• Install
• Example Usage

Credits

This is a slightly modified implementation of Schnorr's protocol that utilizes a state seed. The proofs used are rather complex in nature, but I will do my best to explain its functionality, but please refer to the research papers on which this implementation is based as it does a far more complete job with explanation than I.

Elliptic Curve Based Zero Knowledge Proofs and Their Applicability on Resource Constrained Devices by Ioannis Chatzigiannakis, Apostolos Pyrgelis, Paul G. Spirakis, and Yannis C. Stamatiou

Purpose

Zero-Knowledge Proofs are undoubtedly the future of authentication security within various IT and application development industrires. The ability to verify the veracity of a claim (ex: proving that you know a secret password), without divulging any information about the claim itself (ex: passwords or hashes), allows for servers to guarantee secure AAA operations (authentication, authorization, and accounting) without exposing private information. NoKnow is an implementation of a Non-Interactive Zero-Knowledge Proof protocol specifically designed for verifying text-based secrets, which is ideal for passwords or other authentication means.

How It Works

TODO: explain how it works

API

The noknow Python API is meant to be simple and intuitive:

Core Components

noknow.core.ZKParameters:

The parameters used to initialize the Zero-Knowledge crypto system.

class ZKParameters(NamedTuple):
    """
    Parameters used to construct a ZK proof state using an curve and a random salt
    """
    alg: str                    # Hashing algorithm name
    curve: str                  # Standard Elliptic Curve name to use
    s: int                      # Random salt for the state

noknow.core.ZKSignature:

A crytographic, zero-knowledge signature that can be used to verify future messages.

class ZKSignature(NamedTuple):
    """
    Cryptographic public signature used to verify future messages
    """
    params: ZKParameters        # Reference ZK Parameters
    signature: int              # The public key derived from your original secret

noknow.core.ZKProof:

A cryptograpgic proof that can be verified against a signature.

class ZKProof(NamedTuple):
    """
    Non-deterministic cryptographic zero-knowledge proof that can be verified to ensure the
    private key used to create the proof is the same key used to generate the signature
    """
    params: ZKParameters        # Reference ZK Parameters
    c: int                      # The hash of the signed data and random point, R
    m: int                      # The offset from the secret `r` (`R=r*g`) from c * Hash(secret)

noknow.core.ZKData

Wrapper that contains a proof and the necessary data to validate the proof against a signature.

class ZKData(NamedTuple):
    """
    Wrapper to contain data and a signed proof using the data
    """
    data: Union[str, bytes, int]
    proof: ZKProof

ZK

The ZK class is the central component of NoKnow and its state (defined by ZKParameters) should be inherently known to both the Client (Prover) and Server (Verifier).

instance methods

Method	Parameters	Role	Purpose
create_signature	secret: Union[str, bytes]	Prover	Create a cryptographic signature derived from the value secret to be generated during initial registration and stored for subsequent challenge proofs
sign	secret: Union[str, bytes] data: Union[str, bytes, int]	Prover	Create a ZKData object using the secret and any additional data
verify	challenge: Union[ZKData, ZKProof] signature: ZKSignature data: Optional[Union[str, bytes, int]]	Verifier	Verify the user-provided challenge against the stored signature and randomly generated token to verify the validity of the challenge

Install

NoKnow is available from PyPi! Simply run:

pip install -U noknow

Example Usage

TODO: Include example usage

Example 1

"""
Extremely simple example of NoKnow ZK Proof implementation
"""
from getpass import getpass
from noknow.core import ZK, ZKSignature, ZKParameters, ZKData, ZKProof
from queue import Queue
from threading import Thread


def client(iq: Queue, oq: Queue):
    client_zk = ZK.new(curve_name="secp256k1", hash_alg="sha3_256")

    # Create signature and send to server
    signature = client_zk.create_signature(getpass("Enter Password: "))
    oq.put(signature.dump())

    # Receive the token from the server
    token = iq.get()

    # Create a proof that signs the provided token and sends to server
    proof = client_zk.sign(getpass("Enter Password Again: "), token).dump()

    # Send the token and proof to the server
    oq.put(proof)

    # Wait for server response!
    print("Success!" if iq.get() else "Failure!")


def server(iq: Queue, oq: Queue):
    # Set up server component
    server_password = "SecretServerPassword"
    server_zk = ZK.new(curve_name="secp384r1", hash_alg="sha3_512")
    server_signature: ZKSignature = server_zk.create_signature("SecureServerPassword")

    # Load the received signature from the Client
    sig = iq.get()
    client_signature = ZKSignature.load(sig)
    client_zk = ZK(client_signature.params)

    # Create a signed token and send to the client
    token = server_zk.sign("SecureServerPassword", client_zk.token())
    oq.put(token.dump(separator=":"))

    # Get the token from the client
    proof = ZKData.load(iq.get())
    token = ZKData.load(proof.data, ":")

    # In this example, the server signs the token so it can be sure it has not been modified
    if not server_zk.verify(token, server_signature):
        oq.put(False)
    else:
        oq.put(client_zk.verify(proof, client_signature, data=token))


def main():
    q1, q2 = Queue(), Queue()
    threads = [
        Thread(target=client, args=(q1, q2)),
        Thread(target=server, args=(q2, q1)),
    ]
    for func in [Thread.start, Thread.join]:
        for thread in threads:
            func(thread)


if __name__ == "__main__":
    main()