- Stream-based Ciphers
- Operation: Encrypts data one character or bit at a time, making it a real-time encryption method.
- Examples:
- Caesar Cipher: A stream and shift cipher.
- One-time Pad: A stream cipher that operates on each letter of the plaintext independently.
- Advantages:
- Bit-by-bit substitution using XOR and keystream.
- Emulates the one-time pad, which is theoretically unbreakable.
- No size difference between plaintext and ciphertext.
- Disadvantages:
- Can be difficult to implement correctly.
- Generally weaker than block ciphers.
- Difficult to generate a truly random, unbiased keystream.
- Uses:
- Wireless encryption protocols like WEP and WPA.
- RC4 algorithm.
- Applications in audio and visual data encryption.
- Block-based Ciphers
- Operation: Encrypts data in fixed-size blocks, applying the encryption algorithm to an entire block at once.
- Examples: Transposition ciphers.
- Characteristics:
- Uses both substitution and transposition techniques.
- Not as commonly used or effective in modern wireless networks.
Understanding these methods is crucial for selecting the appropriate cryptographic technique based on the specific needs and constraints of the system or data being protected.