spproto 0.1.3

Secure Peer Protocol

Secure Peer Protocol (SPP)

Description

Chat with friends in a truly cryptographically secure way.

Intended to work as 5th OSI layer usually on top of TCP/IP.

Mechanism

1. shared key is obtained using ECDHE. Transferred DH public keys are signed and verified with pre-obtained Ed25519 public keys.
2. auth key is derived from shared key using HKDF.
3. Message using ChaCha20-Poly1305 with auth key.

Preparation before using

1. Generate private key, give your public key to friend.
2. Get friend's public key through reliable channel.

from pathlib import Path
from spproto.key import generate_private_key, get_public_key

def main() -> None:
    privkey_path = Path('~/Desktop/privkey').expanduser()
    pubkey_path = Path('~/Desktop/pubkey').expanduser()
    
    privkey = generate_private_key()
    pubkey = get_public_key(privkey)
    
    privkey_path.write_bytes(privkey)
    pubkey_path.write_bytes(pubkey)

main()

How to use

Client

Connect to your friend

import asyncio
from pathlib import Path
from spproto.client import connect

async def main() -> None:
    privkey = Path('~/Desktop/privkey').expanduser().read_bytes()
    peer_pubkey = Path('~/Desktop/friend_pubkey').expanduser().read_bytes()

    host = '1.2.3.4'
    port = 4321
    async with connect(host, port, privkey, peer_pubkey) as conn:
        await conn.send(b'Hello, server!')
        print(await conn.receive())

asyncio.run(main())

Server

Make your friend available to connect to you.

import asyncio
from pathlib import Path
from spproto.connection import Connection
from spproto.server import serve

async def callback(
    conn: Connection
) -> None:
    print(await conn.receive())
    await conn.send(b'Hello, client')

async def main() -> None:
    privkey = Path('~/Desktop/privkey').expanduser().read_bytes()
    peer_pubkey = Path('~/Desktop/friend_pubkey').expanduser().read_bytes()

    host = '1.2.3.4'
    port = 4321
    await serve(host, port, privkey, peer_pubkey, callback)

asyncio.run(main())