RC4 (Rivest Cipher 4) is a symmetric stream cipher designed by Ron Rivest in 1987. It was widely used in WEP, WPA, SSL/TLS (RC4 cipher suite), and software like Adobe Acrobat. It is now considered insecure and has been removed from all modern protocols.

RC4 has multiple known biases in its keystream output that allow statistical attacks to recover plaintext. The RC4 cipher suite was prohibited in TLS 1.3 and banned by RFC 7465 in 2015.

RC4 Stream Cipher - Free Online Rivest Cipher 4 Tool

Using the Rivest Cipher 4 Tool

Select between Encrypt or Decrypt mode.
Choose your output format (Base64 or Hex).
Enter your secret key or passphrase.
Input your text and click Run to see the results.

RC4 Stream Cipher: encrypt and decrypt text instantly with the classic Rivest Cipher 4 algorithm. This stream cipher tool is designed for developers and security enthusiasts who need to test legacy systems or understand symmetric encryption mechanics. By running entirely in your browser, the utility ensures that your sensitive keys and plaintexts never leave your local machine, providing a fast and private environment for cryptographic experimentation.

Technical Legacy Crypto Testing and Arcfour

Our tool implements the standard Arcfour algorithm, often used in older protocols like WEP and early versions of SSL/TLS. While this cipher suite is no longer recommended for modern production environments, it remains a valuable resource for educational purposes and legacy support tasks. The generator supports both hex and base64 encodings, allowing you to interface with various data formats seamlessly. Whether you're debugging an old application or studying stream cipher biases, our RC4 utility provides the precision and speed you need.

High-performance implementation of the RC4 / Arcfour algorithm
Support for arbitrary key lengths and text inputs
Flexible output encoding including hexadecimal and base64
Local processing for maximum security and immediate results

Frequently Asked Questions

What does rc4-cipher do?

rc4-cipher rc4 (rivest cipher 4) stream cipher - for testing legacy systems.

What input does rc4-cipher accept?

Paste text directly into the input field, or type your data. Most operations handle Unicode, special characters, and multi-line inputs without issue.

How large an input can I process?

There is no hard limit imposed by this tool. Very large inputs (multi-MB text) process within your browser's available memory. For files larger than 50 MB, a command-line tool may be faster.

Can I download the output?

Yes - every output panel includes a Copy to Clipboard button and a Download as file option. Outputs are saved as plain text or the appropriate file format for the operation.

Analyze your legacy data instantly with this reliable and free utility. Explore more Security tools at Chunky Munster and use this RC4 Stream Cipher for all your technical testing requirements.

RC4 Encrypt & Decrypt online

RC4 (Rivest Cipher 4) stream cipher - for testing legacy systems - runs in your browser