E2 (cipher)

This article is about the block cipher. For other uses, see E2 (disambiguation).

E2

General
Designers	NTT
First published	1998
Successors	Camellia
Cipher detail
Key sizes	128, 192, or 256 bits
Block sizes	128 bits
Structure	Feistel network
Rounds	12

In cryptography, E2 is a symmetric block cipher which was created in 1998 by NTT and submitted to the AES competition.

Like other AES candidates, E2 operates on blocks of 128 bits, using a key of 128, 192, or 256 bits. It uses a 12-round Feistel network. E2 has an input transformation and output transformation that both use modular multiplication, but the round function itself consists only of XORs and S-box lookups. The single 8×8-bit S-box is constructed from the composition of an affine transformation with the discrete exponentiation x¹²⁷ over the finite field GF(2⁸). NTT adopted many of E2's special characteristics in Camellia, which has essentially replaced E2.