Smart cards represent an effective tool for trustworthy portable storage of secret-keys and critical processes needed in many recent applications. We develop a more general Feistel network structure with pre- (or post-) pseudorandom shuffling of the plaintext before (or after, respectively) ciphering it using two reversibly key-linked block ciphers that is suitable for length increasing remotely keyed encryption. After discussing the security of the structure, introducing a novel pseudorandom binary sampling tree-based shuffling scheme, and considering the many advantages of reusability, we use this proposed universal ciphers combining structure for developing practical new ciphers reviving the DES and increasing the security of the AES. We finally present an extremely secure length increasing remotely keyed (smart card-based) encryption/decryption protocol allowing the use of a disposable one-time key for reliable long-term security.
['Yassin M. Y. Hasan']
Pseudorandom shuffling in block ciphers combiners with smart card applications