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StatsToDo : Modified RC4 Encryption

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Introduction Technical Issues Program Algorithm


The contents of this page are experimental and unvalidated. The program is presented as an invitation for those interested to test if the encryption provided is secure. At this stage, the program provided should not be used to encrypt anything serious. The author denies responsibility and liability for any and all consiquences of using the contents of this page.


This page presents an experimental approach to modify the basic RC4 encryption algorithm to overcome its known vulnerability. All readers are invited to test this program, to see if the encryption can be analysed. The author would be grateful for any feedback, which can be sent via the Contact StatsToDo page.

The source code, with a brief explanation, is also posted to Github so that comments and suggestions can also be posted there


RC4 is a simple method of encryption using symmetrical keys (same key to encrypt and decipher), and able to stream (once set up, can repeatedly encrypt or decipher large volumn of content continuously) When RC4 became available in 1980s, it was greeted with enthusiasm because of its simplicity, security, speed, and streaming. It was widely adopted, especially for encrypting messages that are sent over the Internet. Unfortunately, a vulnerablility was discovered after some years, and RC4 is no longer widely used.

This page discusses this vulnerability, and explain an attempt to overcome it. The contents are divided into 6 panels

  • Introduction: This panel
  • Technical Issues: Technical discussions on why and how of modifying RC4
  • Program: Javascript program for standard and modified RC4 encryption
  • Algorithm: Discuss the Javascript code of modified RC4 according to its functions