PERBANDINGAN METODE ALGORITMA KRIPTOGRAFI TRIPLEDES DAN TWOFISH

Triple DES is also known as TDES or, more standard, TDEA (Triple Data

Encryption Algorithm [1]). The non-standard convention to use DES (standard) when we

actually mean DEA (algorithm) is so widespread that in order to avoid confusion we use

it in this article. On the other hand, since there are variations of TDES which use two

different keys (2TDES) and three different keys (3TDES) the non-standard abbreviation

3DES is confusing and should be avoided.

The cipher is a 16-round Feistel network with a bijective F function made up of

four key-dependent 8-by-8-bit S-boxes, a fixed 4-by-4 maximum distance separable

matrix over GF(28), a pseudo-Hadamard transform, bitwise rotations, and a carefully

designed key schedule. A fully optimized implementation of Twofish encrypts on a

Pentium Pro at 17.8 clock cycles per byte, and an 8-bit smart card implementation

encrypts at 1820 clock cycles per byte. Twofish can be implemented in hardware in

14000 gates. The design of both the round function and the key schedule permits a wide

variety of tradeoffs between speed, software size, key setup time, gate count, and

memory. We have extensively cryptanalyzed Twofish; our best attack breaks 5 rounds

with 222,5 chosen plaintexts and 251 effort.