Design of a New Block Cipher Based on Conditional Encryption

In today's digital world, encryption has become a prerequisite for many applications requiring data transfer over open and insecure networks. In addition, the advent and fast evolution of mobile technologies has facilitated the need for lightweight encryption schemes which prove to be strong as well as computationally less expensive than the present day standard ciphers. With this as the source of motivation, the paper proposes a new 128-bit block cipher using 128-bit key and performs 8 rounds of operations. Flexibility in the design paves way for extending the block size as well as the key size. The basic strength of the scheme is the conditional processing and the use of non-linear operations during key expansion to generate round keys and the encryption process. Use of simple negation, shift, XOR and substitution operations makes the scheme computationally efficient and less expensive for high bandwidth applications. Results obtained for different types of inputs show almost equal distribution of 0's and 1's in the cipher. Also, change in the cipher with one bit change in the key or plain text is also drastic and depicts strict avalanche effect. Results indicate the strength of the scheme which is also computationally cheaper than many other standard block ciphers.