Twofish is like the dragon-slaying successor to Blowfish—strong, efficient, and ready for battle in modern cryptography. Here’s a clear and engaging breakdown:

🧠 What Is Twofish?

Twofish is a symmetric-key block cipher developed by Bruce Schneier and others in the late 1990s. It was one of the finalists in the competition to become the Advanced Encryption Standard (AES), though AES eventually went to Rijndael.

⚙️ Key Features

• Block Size: 128 bits (larger than Blowfish’s 64-bit blocks).
• Key Length: Supports key sizes up to 256 bits.
• Rounds: 16 rounds of encryption using a Feistel network.
• Design Goals: Flexibility, speed, and security across software and hardware platforms.

🔄 How It Works (Simplified)

1. Key Expansion: Twofish pre-processes the encryption key to generate several subkeys and S-boxes.
2. Feistel Structure: The algorithm splits data blocks into halves, repeatedly transforms and swaps them using:
   • Key-dependent S-boxes
   • Complex matrix operations
   • Bitwise XOR and shifts
3. Whitening: Data is XORed with parts of the key before and after the rounds—adding extra security.

🛡️ Strengths

• Strong Security: Designed to resist known attacks like differential and linear cryptanalysis.
• Efficient: Good performance on modern CPUs.
• Flexible: Well-suited for applications needing variable key sizes.
• Public Domain: No patents—free for anyone to use.

⚠️ Weaknesses & Considerations

• While secure, it wasn’t chosen as AES, so it’s less commonly used in mainstream applications.
• The complexity of the key schedule may slow down initialization (though it’s lightning fast once running).