Block cipher
lastmod 2018-08-17created 2015-11-294 edits
In cryptography, a block cipher is a symmetric-key cryptosystem that encrypts confidential information in fixed-size blocks. If the information to be encrypted is longer than the block length, a specific mode of operation is used. (e.g., ECB, CBC, OFB, CFB, CTR)
Unlike block ciphers, stream ciphers encrypt bit by bit, using linear and nonlinear operations such as LFSR and NFSR.
Methods for proving the security of block ciphers include differential cryptanalysis (Differential Cryptanalysis), a chosen-plaintext attack, and linear cryptanalysis (Linear Cryptanalysis), a known-plaintext attack.
Block cipher structures include the Feistel structure and the SPN structure.
The Feistel structure has the advantage of not needing an inverse function for encryption and decryption, but it has the disadvantages that the swap (Swap) step requires a lot of computation when implemented, and that the round function used in the cipher must be designed securely. A representative cipher is DES; Single DES is no longer used due to security issues.
Among ciphers developed in Korea, there is SEED, designed on the Feistel structure.
The SPN structure has the disadvantage that it must be designed so that an inverse function is needed for encryption and decryption, but because it can encrypt and decrypt in one pass without moving bits in between, it can be designed more efficiently than the Feistel structure. A representative cipher is AES, which is currently in wide commercial use.
List of Block cipher
| Algorithms | 3-Way, AES, Akelarre, Anubis, ARIA, Blowfish, Camellia, CAST-128, CAST-256, CMEA, CS-Cipher, DEAL, DES, DES-X, FEAL, FOX, FROG, G-DES, GOST, ICE, IDEA, Iraqi block cipher, KASUMI, KHAZAD, Khufu and Khafre, LOKI89/91, LOKI97, Lucifer, MacGuffin, Madryga, MAGENTA, MARS, MISTY1, MMB, NewDES, Noekeon, RC2, RC5, RC6, REDOC, Red Pike, S-1, SAFER, SEED, Serpent, SHACAL, SHARK, Skipjack, Square, TEA, 3DES, Twofish, XTEA |
| Design | Feistel cipher, Key schedule, Product cipher, S-box, SPN |
| Cryptanalysis | Brute-force attack, Linear cryptanalysis / Differential cryptanalysis, Mod n, Related key, XSL |
| Standards | AES process, CRYPTREC NESSIE |
| Other | Avalanche effect, Block size, Initialization vector (IV), Key size, Mode of operation, Piling-up lemma, Weak key |