Secure P2P Micropayment System

This is a P2P micropayment system that supports secure message transmission.

Overview

There are several ways to build the programs:

Build all the programs:
```
make
```
This will generate two programs: client and server, under the current directory.
Or accelerate the building phase with multiple cores:
```
make -j$(nproc)
```
Warning: build with this method may mess up the output messages from builing.
Only build the client program:
```
make client
```
This will only generate client.
Only build the server program:
```
make server
```
This will only generate server.

Clear the outputs generated from the building phase:

make clean

This will delete both client and server.

Run the server side:
```
./server <port>
```
- port: Specify the port to which the server should bind. The range is between [1024, 65535].
Run the client side:
```
./client <host> <port>
```
- host: The host that server is running on. If the server is run locally, type 127.0.0.1.
- port: The port to which the server binds.
Note that it is possible to run multiple clients simultaneously.