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+# API Reference
+
+## SecureChatCompletion Class
+
+The `SecureChatCompletion` class is the main entry point for using the NOMYO secure client. It provides the same interface as OpenAI's ChatCompletion API with end-to-end encryption.
+
+### Constructor
+
+```python
+SecureChatCompletion(
+    base_url: str = "https://api.nomyo.ai",
+    allow_http: bool = False,
+    api_key: Optional[str] = None,
+    secure_memory: bool = True
+)
+```
+
+**Parameters:**
+
+- `base_url` (str): Base URL of the NOMYO Router (must use HTTPS for production)
+- `allow_http` (bool): Allow HTTP connections (ONLY for local development, never in production)
+- `api_key` (Optional[str]): Optional API key for bearer authentication
+- `secure_memory` (bool): Enable secure memory protection (default: True)
+
+### Methods
+
+#### create(model, messages, **kwargs)
+
+Creates a new chat completion for the provided messages and parameters.
+
+**Parameters:**
+
+- `model` (str): The model to use for the chat completion
+- `messages` (List[Dict]): A list of message objects. Each message has a role ("system", "user", or "assistant") and content
+- `**kwargs`: Additional parameters that can be passed to the API
+
+**Supported OpenAI Parameters:**
+
+- `temperature` (float): Sampling temperature (0-2)
+- `max_tokens` (int): Maximum tokens to generate
+- `top_p` (float): Nucleus sampling
+- `frequency_penalty` (float): Frequency penalty
+- `presence_penalty` (float): Presence penalty
+- `stop` (Union[str, List[str]]): Stop sequences
+- `n` (int): Number of completions
+- `stream` (bool): Streaming always = False to minimize de-/encryption overhead 
+- `tools` (List): Tool definitions
+- `tool_choice` (str): Tool selection strategy
+- `user` (str): User identifier
+- `security_tier` (str): Security level ("standard", "high", or "maximum")
+
+**Returns:**
+A dictionary containing the chat completion response with the following structure:
+
+```python
+{
+    "id": str,
+    "object": "chat.completion",
+    "created": int,
+    "model": str,
+    "choices": [
+        {
+            "index": int,
+            "message": {
+                "role": str,
+                "content": str,
+                "tool_calls": List[Dict]  # if tools were used
+            },
+            "finish_reason": str
+        }
+    ],
+    "usage": {
+        "prompt_tokens": int,
+        "completion_tokens": int,
+        "total_tokens": int
+    }
+}
+```
+
+#### acreate(model, messages, **kwargs)
+
+Async alias for create() method.
+
+**Parameters:** Same as create() method
+
+**Returns:** Same as create() method
+
+## SecureCompletionClient Class
+
+The `SecureCompletionClient` class handles the underlying encryption, key management, and API communication.
+
+### Constructor
+
+```python
+SecureCompletionClient(router_url: str = "https://api.nomyo.ai", allow_http: bool = False)
+```
+
+**Parameters:**
+
+- `router_url` (str): Base URL of the NOMYO Router (must use HTTPS for production)
+- `allow_http` (bool): Allow HTTP connections (ONLY for local development, never in production)
+
+### Methods
+
+#### generate_keys(save_to_file: bool = False, key_dir: str = "client_keys", password: Optional[str] = None)
+
+Generate RSA key pair for secure communication.
+
+**Parameters:**
+
+- `save_to_file` (bool): Whether to save keys to files
+- `key_dir` (str): Directory to save keys (if save_to_file is True)
+- `password` (Optional[str]): Optional password to encrypt private key
+
+#### load_keys(private_key_path: str, public_key_path: Optional[str] = None, password: Optional[str] = None)
+
+Load RSA keys from files.
+
+**Parameters:**
+
+- `private_key_path` (str): Path to private key file
+- `public_key_path` (Optional[str]): Path to public key file (optional, derived from private key if not provided)
+- `password` (Optional[str]): Optional password for encrypted private key
+
+#### fetch_server_public_key()
+
+Fetch the server's public key from the /pki/public_key endpoint.
+
+**Returns:**
+Server's public key as PEM string
+
+#### encrypt_payload(payload: Dict[str, Any])
+
+Encrypt a payload using hybrid encryption (AES-256-GCM + RSA-OAEP).
+
+**Parameters:**
+
+- `payload` (Dict[str, Any]): Dictionary containing the chat completion request
+
+**Returns:**
+Encrypted payload as bytes
+
+#### decrypt_response(encrypted_response: bytes, payload_id: str)
+
+Decrypt a response from the secure endpoint.
+
+**Parameters:**
+
+- `encrypted_response` (bytes): Encrypted response bytes
+- `payload_id` (str): Payload ID for metadata verification
+
+**Returns:**
+Decrypted response dictionary
+
+#### send_secure_request(payload: Dict[str, Any], payload_id: str, api_key: Optional[str] = None, security_tier: Optional[str] = None)
+
+Send a secure chat completion request to the router.
+
+**Parameters:**
+
+- `payload` (Dict[str, Any]): Chat completion request payload
+- `payload_id` (str): Unique identifier for this request
+- `api_key` (Optional[str]): Optional API key for bearer authentication
+- `security_tier` (Optional[str]): Optional security tier for routing
+
+**Returns:**
+Decrypted response from the LLM
+
+## Exception Classes
+
+### APIError
+
+Base class for all API-related errors.
+
+### AuthenticationError
+
+Raised when authentication fails (e.g., invalid API key).
+
+### InvalidRequestError
+
+Raised when the request is invalid (HTTP 400).
+
+### APIConnectionError
+
+Raised when there's a connection error.
+
+### RateLimitError
+
+Raised when rate limit is exceeded (HTTP 429).
+
+### ServerError
+
+Raised when the server returns an error (HTTP 500).
+
+### SecurityError
+
+Raised when a security violation is detected.