RC4 Encryption Explained - KSA and PRGA Step-by-Step with Example

Learn the RC4 (Rivest Cipher 4) stream cipher algorithm through a comprehensive step-by-step tutorial that demonstrates how this historically significant encryption method transforms plaintext into ciphertext. Explore the algorithm's background and its role in early SSL/TLS and WEP implementations before diving into its two core components. Master the Key Scheduling Algorithm (KSA) by observing how a secret key scrambles the initial 256-byte State Array, then understand the Pseudo-Random Generation Algorithm (PRGA) that uses this scrambled array to generate a continuous keystream. Follow along with a practical encryption and decryption example using XOR operations to see the algorithm in action. Examine both the advantages that made RC4 popular in early cryptographic applications and the vulnerabilities that led to its classification as "broken" by modern security standards, providing essential context for understanding why this cipher is no longer recommended for secure communications.