Cryptography Lecture 5 - Block vs. Stream Cipher and DES

Block ciphers process messages a bit at a time when encrypting/decrypting.

DES is a stream cipher.

DES uses a 56-bit key size.

The encryption and decryption algorithms of DES are classified.

The DES single round structure uses two 16-bit L & R halves.

DES S-Boxes map 4 to 6 bits.

The 48-bit binary number is split up into 6 (8-bit) blocks.

Each S-box extracts eight numbers from the binary number.

Triple DES uses two keys and two executions of the DES algorithm.

AES has a fixed block size of 128 bits.

Blowfish has a variable key length ranging from 32 bits up to 448 bits.

Cast-128 has a block size of 128 bits and a key size of 256 bits.