I smell a new npub-based ssl certificate replacement for relays coming

Chatgpt:

Using Elliptic Curve Cryptography (ECC) is a great way to align with NOSTR's encryption and signing schemes. Here’s how you can create a secure WebSocket communication using ECC for encryption and signing, similar to how NOSTR handles notes.

### Step-by-Step Guide

#### 1. Key Generation

Generate ECC key pairs for the server and client using `cryptography` library in Python.

#### 2. Implement the Relay Server

The relay server will use its private key to decrypt the initial connection request and then use symmetric encryption (AES) for the WebSocket communication.

#### 3. Implement the Client

The client will use the server's public key to encrypt the initial connection request.

### Example Code

#### 1. Key Generation

Use the `cryptography` library to generate ECC key pairs.

```python

from cryptography.hazmat.primitives.asymmetric import ec

from cryptography.hazmat.primitives import serialization

# Generate server private key

server_private_key = ec.generate_private_key(ec.SECP256R1())

server_public_key = server_private_key.public_key()

# Save server private key

with open("server_private_key.pem", "wb") as f:

f.write(server_private_key.private_bytes(

encoding=serialization.Encoding.PEM,

format=serialization.PrivateFormat.PKCS8,

encryption_algorithm=serialization.NoEncryption()

))

# Save server public key

with open("server_public_key.pem", "wb") as f:

f.write(server_public_key.public_bytes(

encoding=serialization.Encoding.PEM,

format=serialization.PublicFormat.SubjectPublicKeyInfo

))

```

#### 2. Relay Server Implementation

Using the `websockets` library and `cryptography` for the relay server.

```python

import asyncio

import websockets

from cryptography.hazmat.primitives.asymmetric import ec

from cryptography.hazmat.primitives import hashes

from cryptography.hazmat.primitives.kdf.hkdf import HKDF

from cryptography.hazmat.primitives import serialization

from cryptography.hazmat.primitives.kdf.concatkdf import ConcatKDFHash

from cryptography.hazmat.primitives.kdf.concatkdf import ConcatKDFHash

from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes

from cryptography.hazmat.primitives.ciphers.aead import AESGCM

from base64 import b64encode, b64decode

import os

# Load server private key

with open("server_private_key.pem", "rb") as f:

server_private_key = serialization.load_pem_private_key(

f.read(),

password=None

)

# Function to handle WebSocket connections

async def echo(websocket, path):

try:

# Receive the client's public key

client_public_key_pem = await websocket.recv()

client_public_key = serialization.load_pem_public_key(client_public_key_pem.encode('utf-8'))

# Perform ECDH key exchange

shared_key = server_private_key.exchange(ec.ECDH(), client_public_key)

# Derive AES key from the shared key

aes_key = HKDF(

algorithm=hashes.SHA256(),

length=32,

salt=None,

info=b'handshake data'

).derive(shared_key)

while True:

encrypted_message = await websocket.recv()

nonce, ciphertext, tag = [b64decode(x) for x in encrypted_message.split(":")]

# Decrypt the message

aesgcm = AESGCM(aes_key)

message = aesgcm.decrypt(nonce, ciphertext + tag, None).decode('utf-8')

print(f"Received: {message}")

response = f"Echo: {message}"

# Encrypt response

nonce = os.urandom(12)

aesgcm = AESGCM(aes_key)

ciphertext = aesgcm.encrypt(nonce, response.encode('utf-8'), None)

encrypted_response = b64encode(nonce).decode('utf-8') + ":" + b64encode(ciphertext[:-16]).decode('utf-8') + ":" + b64encode(ciphertext[-16:]).decode('utf-8')

await websocket.send(encrypted_response)

except websockets.exceptions.ConnectionClosed as e:

print(f"Connection closed: {e}")

# Start the WebSocket server

start_server = websockets.serve(echo, "localhost", 8765)

asyncio.get_event_loop().run_until_complete(start_server)

asyncio.get_event_loop().run_forever()

```

#### 3. Client Implementation

The client will use the server's public key to perform ECDH key exchange and then use the derived AES key for encryption.

```python

import asyncio

import websockets

from cryptography.hazmat.primitives.asymmetric import ec

from cryptography.hazmat.primitives import hashes

from cryptography.hazmat.primitives.kdf.hkdf import HKDF

from cryptography.hazmat.primitives import serialization

from cryptography.hazmat.primitives.kdf.concatkdf import ConcatKDFHash

from cryptography.hazmat.primitives.ciphers.aead import AESGCM

from base64 import b64encode, b64decode

import os

# Load server public key

with open("server_public_key.pem", "rb") as f:

server_public_key = serialization.load_pem_public_key(f.read())

async def hello():

uri = "ws://localhost:8765"

# Generate client private key

client_private_key = ec.generate_private_key(ec.SECP256R1())

client_public_key = client_private_key.public_key()

# Perform ECDH key exchange

shared_key = client_private_key.exchange(ec.ECDH(), server_public_key)

# Derive AES key from the shared key

aes_key = HKDF(

algorithm=hashes.SHA256(),

length=32,

salt=None,

info=b'handshake data'

).derive(shared_key)

async with websockets.connect(uri) as websocket:

# Send client's public key to the server

client_public_key_pem = client_public_key.public_bytes(

encoding=serialization.Encoding.PEM,

format=serialization.PublicFormat.SubjectPublicKeyInfo

).decode('utf-8')

await websocket.send(client_public_key_pem)

message = "Hello, Server!"

print(f"Sending: {message}")

# Encrypt the message

nonce = os.urandom(12)

aesgcm = AESGCM(aes_key)

ciphertext = aesgcm.encrypt(nonce, message.encode('utf-8'), None)

encrypted_message = b64encode(nonce).decode('utf-8') + ":" + b64encode(ciphertext[:-16]).decode('utf-8') + ":" + b64encode(ciphertext[-16:]).decode('utf-8')

await websocket.send(encrypted_message)

encrypted_response = await websocket.recv()

nonce, ciphertext, tag = [b64decode(x) for x in encrypted_response.split(":")]

# Decrypt the response

aesgcm = AESGCM(aes_key)

response = aesgcm.decrypt(nonce, ciphertext + tag, None).decode('utf-8')

print(f"Received: {response}")

asyncio.get_event_loop().run_until_complete(hello())

```

### Summary

1. **Key Generation**: Generate ECC key pairs for the server and client.

2. **Relay Server**: Implement the server to handle WebSocket connections, perform ECDH key exchange, and use AES-GCM for symmetric encryption.

3. **Client**: Implement the client to perform ECDH key exchange and use AES-GCM for encryption.

This setup ensures that WebSocket communication is encrypted using keys derived from the public-private key pairs, aligning with NOSTR's encryption scheme and avoiding centralized CAs.