The New Approach of AES Key Schedule for Lightweight Block Ciphers

This paper considers block ciphers and key schedule algorithm that is one of the crucial components of a block cipher. It computes round keys/subkeys for relevant round from a short key. The presented experiments show that proposed key schedule algorithm which inspired by Advanced Encryption Standard's (AES) key schedule has desirable properties: Avalanche Effect and Strict Avalanche Criterion (SAC). It satisfies good bit confusion and diffusion. The average success rate of the proposed key schedule algorithm for the SAC test is 95%. As a side result it was found that while testing SAC effect computed values that lie between confidence lower and upper bounds, greater than upper bounds and less than lower bound all of them reach normal distribution. Also based on example given experimental result, proposed structure exhibits a very strong Avalanche Effect because almost at the first round approximately half the bits are changed in the key.