Nahrainfish: A green cryptographic block cipher

In this work, we propose a new block cipher that is called Nahrainfish, which we believe that it offers the required security level for present and foreseeable future without a big sacrifice in efficiency and other related criteria. Instead of building Nahrainfish totally from scratch, we have made a benefit from the concepts of green cryptography and some AES (Advanced Encryption Standard) finalists to develop the new cipher in such a way to obtain the required higher security level. Nahrainfish is a classical Feistel network based on a novel combination of both key-dependent S-boxes and data-dependent rotations. It operates on 128-bit blocks and accepts a variable key length up to 1024 bits. The paper also includes some important notes on the security and performance of the cipher.