This is a question out of curiosity! I really dont know of any other block cipher that is as secure as AES that has a ***substitution permutation*** structure and can be used as an alternative to AES to protect implementations from cache timing attacks. Searching Google, revealed other NIST finalists, but the best of them had a *Fiestel structure*. There are also many others, but the confidence on their security is ***less*** compared to AES. I am looking for a good block cipher that is similar in structure to AES with same level of security, and efficient to implement in software, for both small and large devices... Every help will be greatly appreciated!!!