Symmetric-Key Encryption
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What is symmetric-key encryption? 🔗
An encryption method that uses the same key for encryption and decryption.
It is also known as secret-key encryption.
Examples include classical ciphers, block ciphers (DES, AES, ARIA, and SEED), and stream ciphers (RC4 and ChaCha).
Advantages: Faster and more efficient than asymmetric-key encryption.
Disadvantages: The problem of sharing keys and the need to manage large numbers of them.
Block ciphers 🔗
A symmetric-key encryption method that encrypts data in fixed-size blocks.
Input: One block of elements at a time.
Output: An encrypted block for each input block.
The key can be reused, and this is a common encryption approach.
Representative block ciphers: Substitution ciphers, permutation ciphers, DES, AES, ARIA, and SEED.
Periodically renewing the key is recommended for security.
Stream ciphers 🔗
A symmetric-key encryption method that encrypts data bit by bit.
Input: A continuous stream of bits.
Output: An encrypted bit for each input bit.
Advantages:
- Faster than block ciphers.
- The key is used only once.
Disadvantages:
- Vulnerable to known-plaintext attacks.
Representative stream ciphers: RC4, ChaCha, and LFSR.