OpenSSL chatty

Description

A multithread client-server chat application. Every communication between peers is encrypted using OpenSSL API.

For more details, visit instructions and report

How it works

When a client correctly connects to the server, the server will shows online users to this client, then the client can requests a chat session with some other client. This client will be wait for the peer response. As for now there are 3 users registered to the server. If you want create your own customers, you should generate a pair of 2048-bit RSA keys and the private key must be protected by password. The server has a public certificate that is granted to be safe by the CA SimpleAuthority.

Prerequisites

The programs needs the installation of OpenSSL, a TLS/SSL and crypto library.

Install OpenSSL on Ubuntu/Debian

First of all, install build dependencies, then clone OpenSSL and configure it.

sudo apt-get -y install build-essential checkinstall git zlib1g-dev
git clone --depth 1 --branch OpenSSL_1_1_1g https://github.com/openssl/openssl.git
cd openssl
./config zlib '-Wl,-rpath,$(LIBRPATH)'

After you have built and tested, install OpenSSL and configure the shared libs.

make
make test
sudo make install
sudo ldconfig -v

Finally, check the OpenSSL version to make sure you have successfully completed all the steps.

openssl version

Install SimpleAuthority

If you want to generate your own certificate, you should download the program at the following link: SimpleAuthority

2048-bit RSA Generation

How to generate a pair of 2048-bit RSA keys using OpenSSL command-line tools.

RSA private key: the following command generate a .pem file, protected by a user-chosen password, containing a 2048-bit key.

openssl genrsa -aes256 -out private_key.pem 2048

RSA public key: a private key in OpenSSL is represented with a strcuture that contains also the public key, so the following command extract the public key from the private key.

openssl rsa -pubout -aes256 -in private_key.pem -out public_key.pem

Usage

Before running the programs, you have first to compile them with -lcrypto and -lpthread to include the right library.

cd src/server
g++ server.cc -lcrypto -lpthread
./a.out

cd src/client
g++ client.cc -lcrypto -lpthread
./a.out

fedehsq/openssl_chatty