RC4 facts for kids

RC4, also known as ARC4, is a type of secret code used to keep information safe. It's one of the most common ways to scramble data quickly, especially in computer programs. You might have used it without knowing!

RC4 helps protect your internet traffic when you visit secure websites (like when you see "https://" in the address bar). It also used to help secure wireless networks, like your home Wi-Fi.

This coding method was created by a person named Ron Rivest in 1987. The "RC" in RC4 stands for "Rivest Cipher" or sometimes "Ron's Code."

For a while, RC4 was a secret. But in 1994, someone shared how it worked on the internet. People quickly realized it was the real deal because it matched how licensed RC4 software worked. Even though the method is now public, the name "RC4" is still a trademark. Because of this, people sometimes call it "ARCFOUR" to avoid any legal issues.

RC4 became very popular because it's simple to use and works very fast. It's easy to add RC4 to both software and hardware devices.

To start RC4, you use a secret key, which can be different lengths. This key goes through a special process called the key-scheduling algorithm (KSA). After that, another process called the pseudo-random generation algorithm (PRGA) creates the scrambled bits that protect your information.

Even though RC4 is fast and simple, experts who study secret codes have found many ways to break it. Because of this, it's not recommended for new applications today. Some older uses of RC4, like in early Wi-Fi security (WEP), were found to be very insecure.

Systems Using RC4

Many systems have used RC4 to keep data safe. Sometimes, RC4 was one of several coding methods a system could choose from.

• WEP (older Wi-Fi security)
• WPA (another Wi-Fi security method)
• BitTorrent protocol encryption (for sharing files)
• Microsoft Point-to-Point Encryption
• Secure Sockets Layer (for secure internet connections, often optional)
• Secure Shell (for secure remote access to computers, often optional)
• Remote Desktop Client (RDC over RDP) (for controlling a computer from far away)
• Kerberos (a network security system, often optional)
• SASL Mechanism Digest-MD5 (for authentication, often optional)
• Gpcode.AK (a computer virus that used RC4 to lock files)

Related Topics

• Advanced Encryption Standard (AES)
• Data Encryption Standard (DES)
• eSTREAM (a project that looked for new ways to scramble information)
• TEA (a simple type of secret code)
• Triple DES (TDES)

Images for kids

• RC4

  A representation of RC4

• RC4 in WEP

  How RC4 was used in WEP

See also

In Spanish: RC4 para niños