feat(server): add development garbler server

server/README.md

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+# Secure Arithmetic Evaluation with s2n-quic and Gateway Evaluator
+
+This repository provides a secure arithmetic evaluation server and client using **garbled circuits** over **QUIC protocol**. The server and client securely communicate to perform arithmetic operations within a garbled circuit framework. It demonstrates a sample function, `multi_arithmetic`, using the `s2n-quic` library, tracing for logging, and gateway evaluator and garbler components.
+
+## Features
+
+- **Garbled Circuit Evaluation**: Uses a garbled circuit framework to perform arithmetic operations.
+- **QUIC Protocol Communication**: Implements secure, low-latency communication between client and server with s2n-quic.
+- **Secure Multiparty Computation (MPC)**: Protects sensitive data during evaluation.
+- **Logging and Debugging**: Logs key steps in the connection process and computation.
+
+## Prerequisites
+
+## Installation
+
+1. **Clone the repository**:
+    ```sh
+    git clone https://github.com/Gateway-DAO/priv.git
+    cd secure-eval-quic
+    ```
+
+2. **Generate Certificates**:
+   Place the server's TLS certificate and private key files in `server/certs/` with the names `cert.pem` and `key.pem`. This enables secure communication over QUIC.
+
+3. **Build the Project**:
+    ```sh
+    cargo build --release
+    ```
+
+## Usage
+
+The project contains two main components:
+
+1. **Server**: Hosts the garbled circuit and accepts connections from clients to perform arithmetic operations.
+2. **Client**: Initiates the garbling process and interacts with the server to evaluate the circuit.
+
+### Run the Server
+
+```sh
+cargo run --bin server
+```
+
+The server listens on `127.0.0.1:4433` and logs its status.
+
+### Run the Client
+
+In a separate terminal, start the client:
+
+```sh
+cargo run --bin client
+```
+
+The client connects to the server, initiates a garbling interaction, and exchanges data with the server. The final result is printed once the garbler completes the evaluation.
+
+### Example Circuit Evaluation
+
+The example circuit, `multi_arithmetic`, performs a sample arithmetic calculation:
+
+```rust
+#[circuit(compile)]
+fn multi_arithmetic(a: u8, b: u8, c: u8, d: u8) -> u8 {
+    let res = a * b;
+    let res = res + c;
+    res - d
+}
+```
+
+This sample multiplies `a` and `b`, adds `c`, then subtracts `d`.
+
+## Code Overview
+
+- **Server**:
+  - Sets up the QUIC server with TLS, starts accepting connections, and creates an evaluator for the `multi_arithmetic` circuit.
+  - The evaluator processes incoming data from the client, computes the circuit’s result, and returns it to the client.
+
+- **Client**:
+  - Connects to the server, sets up the garbler for the `multi_arithmetic` circuit, and sends initial data.
+  - Receives responses from the server, updates the garbler state, and exchanges messages until evaluation is complete.
+
+### Key Functions
+
+- `multi_arithmetic`: Example circuit function performing a basic arithmetic operation.
+- `handle_evaluator_connection`: Manages evaluator interactions on the server side.
+- `handle_garbler_connection`: Manages garbler interactions on the client side.
+
+## Logging and Debugging
+
+Logging is set up with `tracing_subscriber`. Key steps, data sizes, and message contents are logged for debugging and understanding the data flow. To adjust the logging level, modify `RUST_LOG` before running:
+
+```sh
+RUST_LOG=info cargo run --bin server
+```
+
+## Future Improvements
+
+- Implement additional circuit examples and complexity.
+- Enhance modular arithmetic for complete garbled circuit operations.
+- Add support for dynamic circuit generation.
+
+## License
+
+This repository is licensed under the MIT License. See [LICENSE](LICENSE) for details.
+
+---
+
+This README provides a comprehensive overview of the secure evaluation setup over QUIC using garbled circuits. For any questions or issues, please reach out via GitHub Issues.