Blowfish
Blowfish is a symmetric-key block cipher algorithm designed in 1993 by Bruce Schneier as a fast, free alternative to existing encryption methods. It operates on 64-bit blocks of data with a variable key length from 32 to 448 bits, using a Feistel network structure for encryption and decryption. While widely used in the 1990s and early 2000s, it has been largely superseded by more modern algorithms like AES due to vulnerabilities in its small block size.
Developers should learn Blowfish primarily for historical context in cryptography or when maintaining legacy systems that still use it, as it was once popular in applications like file encryption and network protocols. It's also useful for educational purposes to understand block cipher design principles, such as Feistel networks and key scheduling, but modern projects should avoid it in favor of more secure alternatives like AES due to its known weaknesses.