Python

Description:

In Python, the jwt and ecdsa libraries are used to generate JWT tokens and to sign messages respectively. The uuid library is used to generate a unique identifier for the Id field.

Required Libraries:

1. PyJWT: A Python library to encode and decode JWT tokens.

2. ecdsa: A Python library for signing and verifying messages using ECDSA.

3. uuid: A Python library to generate unique identifiers.

4. cryptography : A Python library provides cryptographic recipes and primitives.

pip install PyJWT ecdsa cryptography

import jwt
import ecdsa
from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
import uuid
import datetime
import base64

# Key generation for JWT
private_key_jwt = ecdsa.SigningKey.generate(curve=ecdsa.NIST521p)
public_key_jwt = private_key_jwt.verifying_key

# Key generation for ECDH
private_key_ecdh = ec.generate_private_key(ec.SECP256R1(), default_backend())
peer_public_key = ec.generate_private_key(ec.SECP256R1(), default_backend()).public_key()

def private_key_to_pem(sk):
    # Convert the SigningKey to a PEM formatted string
    return sk.to_pem().decode()

def sign_message(message, private_key):
    signature = private_key.sign(message.encode())
    return base64.b64encode(signature).decode()

def encrypt_message_ecdh(message):
    shared_key = private_key_ecdh.exchange(ec.ECDH(), peer_public_key)
    return shared_key[:len(message)].hex()  # Return as hex for simplicity

def generate_etamp():
    header = {
        "alg": "ES512",
        "typ": "ETAMP"
    }
    
    current_time = datetime.datetime.now(datetime.timezone.utc)
    expiration_time = current_time + datetime.timedelta(seconds=3600)  # 1 hour later
    not_before_time = current_time

    senderServerId = str(uuid.uuid4())
    senderId = str(uuid.uuid4())
    recipientId = str(uuid.uuid4())
    message_id = str(uuid.uuid4())

    payload = {
        "jti": str(uuid.uuid4()),
        "exp": int(expiration_time.timestamp()),
        "nbf": int(not_before_time.timestamp()),
        "messageId": message_id,
        "senderUserName": "user1",
        "senderId": senderId,
        "recipient": "user2",
        "recipientId": recipientId,
        "senderServerName": "WebServer1",
        "senderServerId": senderServerId,
        "recipientServerName": "WebServer1",
        "recipientServerId": senderServerId,
        "iss": f"{senderServerId}.WebServer1.user1.{senderId}",
        "sub": "Message",
        "audience": f"{senderServerId}.WebServer1.user2.{recipientId}",
        "message": encrypt_message_ecdh("This is a secret message"),
        "timestamp": current_time.strftime('%Y-%m-%dT%H:%M:%SZ')
    }
    
    pem_private_key = private_key_to_pem(private_key_jwt)
    token = jwt.encode(payload, pem_private_key, algorithm="ES512", headers=header)

    # ETAMP structure for a message
    message_etamp = {
        "Id": message_id,
        "Token": token,
        "SignatureToken": sign_message(token, private_key_jwt),
        "SignatureMessage": sign_message(message_id + token + sign_message(token, private_key_jwt), private_key_jwt)
    }

    return message_etamp

if __name__ == "__main__":
    print(generate_etamp())