JSChat - A Secure Chat and File Transfer Program

JSChat is a platform independent secure chat and file transfer program written in Java Swing.

JSChat is free software, distributed under the GNU General Public License version 3.

Features

• Real-time text based chat
• File transfer
• Text chat and file transfers can be encrypted
• Encryption utilities (Key Generation/File encryption|decryption/SHA/MD5/Base64)
• Resume file transfer (for interrupted or cancelled transfers)
• CRC32 File integrity check
• DNS Host / IP lookup
• Multi-threading (continue chatting while your files transfer)
• Save last used settings
• Skins (as available for JRE for your platform)

What do I need to run JSChat?

• JSChat.jar binary (run ant jar)
• Install a Java Runtime Environment (minimum Java 1.5)
• Save Bouncy Castle's JCA Provider bcprov-jdk15on-148.jar to JSChat's lib directory
• Install Oracle's unlimited strength JCE
• Run run.bat or run.sh (or manually java "dist/JSChat.jar:lib/bcprov-jdk15on-148.jar" chat.JSChat)

Encryption Details

• Public/Private Keys are RSA, 1024 bit
• Text chat uses RC4, 1024 bit
• File transfer uses AES, 256 bit, CBC, PKCS#5
• Key store uses PBE with SHA and Twofish CBC

Future changes are likely to include:

• Make encryption implementations configurable

Session Key Exchange Process

• Person 1 generates 1st half of session key and complete initialisation vector
• Person 1 then encrypts these with the Person 2's public key
• Person 1 then sends the encrypted data to Person 2
• Person 2 decrypts 1st half key and vector using their private key
• Person 2 generates 2nd half of the session key
• Person 2 then encrypts these with the Person 1's public key
• Person 2 then sends the encrypted data to Person 1
• Person 1 decrypts 2nd half key using their private key
• Each end now has 1st and 2nd half of key and initialisation vector

Key loading via a password protected key-store will be added next

Development

JSChat is a standard Ant and Java build.

History

This program is a based on a non-encrypted program, version written in 1999 in a couple of sittings. Encryption was added using the ABA JCE in 2001. It has recently been open-sourced and updated to work with Bouncy Castle.