E2, e2, E02, E.II, e² or E-2 may refer to:
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 x over the finite field GF(2). NTT adopted many of E2's special characteristics in Camellia, which has essentially replaced E2.
e2 was a Turkish television channel launched in January 2007 that often broadcasts American series. It is owned by the Doğuş Group. The channel closed on January 31, 2016.
E2 is a viral structural protein found in the hepatitis C virus. It is present on the viral membrane and functions as a host receptor binding protein, mediating entry into host cells. Therefore, it is a key target for the design of entry inhibitors and vaccine immunogens.