SocketChat App

A Chat Application is where many users or clients connect to have a conversation and share information. A server is set up which enables clients to connect to each other, the conversation the clients have should be encrypted to secure critical information. Sockets allow communication between two different processes on the same or different machines. To be more precise, it’s a way to talk to other computers using standard Unix file descriptors. In Unix, every I/O action is done by writing or reading a file descriptor. A file descriptor is just an integer associated with an open file and it can be a network connection, a text file, a terminal, or something else. To a programmer, a socket looks and behaves much like a low-level file descriptor. This is because commands such as read() and write() work with sockets in the same way they do with files and pipes.

Socket.IO provides the ability to implement real-time analytics, binary streaming, instant messaging, and document collaboration. Notable users include Microsoft Office, Yammer, and Zendesk. Socket.IO handles the connection transparently. It will automatically upgrade to WebSocket if possible. This requires the programmer to only have Socket.IO knowledge. Socket.IO is not a WebSocket library with fallback options to other real time protocols. It is a custom real time transport protocol implementation on top of other real time protocols. A Socket.IO implementing server cannot connect to a non-Socket.IO WebSocket client. A Socket.IO implementing client cannot talk to a non-Socket.IO WebSocket or Long Polling Comet server. Socket.IO requires using the Socket.IO libraries on both client and server side. As of version 2.0, Socket.IO makes use of WebSockets as the underlying WebSocket library.

The Advanced Encryption Standard (AES) is a symmetric block cipher chosen by the U.S. government to protect classified information. AES is implemented in software and hardware throughout the world to encrypt sensitive data. It is essential for government computer security, cybersecurity and electronic data protection. The National Institute of Standards and Technology (NIST) started development of AES in 1997 when it announced the need for an alternative to the Data Encryption Standard (DES), which was starting to become vulnerable to brute-force attacks. NIST stated that the newer, advanced encryption algorithm would be unclassified and must be “capable of protecting sensitive government information well into the [21st] century.” It was intended to be easy to implement in hardware and software, as well as in restricted environments – such as a smart card – and offer decent defenses against various attack techniques. AES was created for the U.S. government with additional voluntary, free use in public or private, commercial or noncommercial programs that provide encryption services. However, nongovernmental organizations choosing to use AES are subject to limitations created by U.S. export control.

AES includes three block ciphers: AES-128, AES-192 and AES-256. AES-128 uses a 128-bit key length to encrypt and decrypt a block of messages, while AES-192 uses a 192-bit key length and AES-256 a 256-bit key length to encrypt and decrypt messages. Each cipher encrypts and decrypts data in blocks of 128 bits using cryptographic keys of 128, 192 and 256 bits, respectively. Symmetric, also known as secret key, ciphers use the same key for encrypting and decrypting, so the sender and the receiver must both know – and use – the same secret key. The government classifies information in three categories: Confidential, Secret or Top Secret. All key lengths can be used to protect the Confidential and Secret level. Top Secret information requires either 192- or 256-bit key lengths. There are 10 rounds for 128-bit keys, 12 rounds for 192-bit keys and 14 rounds for 256-bit keys. A round consists of several processing steps that include substitution, transposition and mixing of the input plaintext to transform it into the final output of ciphertext.

Codebase: https://github.com/hoplite2k/encrypted-socketchat-application