SEED

SEED is a 128-bit symmetric key block cipher that the Korea Information Security Agency has developed since 1998 and that is a national standard encryption algorithm in the Republic of Korea. It has a Feistel structure with 16 rounds, a 128-bit block and a 128-bit key. The round function uses two 8x8 S-boxes, permutations, rotations and a mix of exclusive OR and modular addition, and it was designed to balance security against differential cryptanalysis, linear cryptanalysis and related key attacks with efficiency. SEED has been widely used in Korea for confidential services such as electronic commerce and financial services over wired and wireless communication. RFC 4269, published in December 2005 by Lee, Lee, Yoon, Cheon and Lee of KISA, describes the cipher and its key schedule, and it obsoletes RFC 4009 because that text had ambiguous function and S-box definitions; the SEED algorithm itself was not changed.