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Client Reference Implementation

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Overview

This document provides a reference implementation guide for ATH protocol clients. Developers can use this as a basis to implement complete client functionality.

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Core Modules

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1. Identity Management Module

Responsible for managing the client DID identity and public/private key pairs: 
class IdentityManager:
    def __init__(self):
        self.did = None
        self.private_key = None
        self.public_key = None
    
    def generate_identity(self):
        # Generate a new DID and public/private key pair
        pass
    
    def load_identity(self, file_path):
        # Load identity information from a file
        pass
    
    def sign(self, data):
        # Sign data using the private key
        pass

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2. Authorization Management Module

Responsible for managing user authorization credentials: 
class AuthorizationManager:
    def __init__(self):
        self.user_credentials = {}
    
    def request_user_authorization(self, scopes):
        # Request authorization from the user
        pass
    
    def get_credential(self, scopes):
        # Retrieve the authorization credential for the specified scopes
        pass
    
    def store_credential(self, credential):
        # Securely store the authorization credential
        pass

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3. Handshake Client Module

Responsible for implementing the complete handshake flow: 
class HandshakeClient:
    def __init__(self, identity_manager, auth_manager):
        self.identity_manager = identity_manager
        self.auth_manager = auth_manager
        self.session = None
    
    def initiate_handshake(self, server_url, scopes):
        # 1. Send handshake request
        # 2. Process server response
        # 3. Send identity proof
        # 4. Process identity verification result
        # 5. Send permission request
        # 6. Wait for permission approval result
        # 7. Complete key negotiation
        # 8. Establish session
        pass
    
    def send_request(self, path, data):
        # Encrypt and send business requests using the session key
        pass

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Handshake Flow Implementation Example

# Initialize the client
identity_manager = IdentityManager()
identity_manager.load_identity("client_identity.json")
auth_manager = AuthorizationManager()
client = HandshakeClient(identity_manager, auth_manager)
# Initiate the handshake
session = client.initiate_handshake(
    "https://api.example.com/ath/handshake",
    scopes=["user:read", "data:write"]
)
# Send business requests using the session
response = client.send_request("/api/user/data", {"param": "value"})

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Security Best Practices

  1. Private keys must be stored using a Hardware Security Module (HSM) or secure storage
  2. User authorization credentials must be stored encrypted, using the user’s password as the encryption key
  3. Session keys must be regenerated for each handshake and must not be reused
  4. Regularly rotate DID and public/private key pairs to reduce the risk of leakage