Novel remotely keyed encryption schemes for smart card applications

The Remotely Keyed Encryption Schemes (RKESs) are greatly useful in solving the vital problem of how to do bulk encryption/decryption for high-bandwidth applications (like multimedia data encryption) in a way that takes advantage of both the superior power of the host and the superior security of the smart card. Accordingly, we propose two novel RKESs, a Length Preserving (LP) RKES and a Length Increasing (LI) RKES. The proposed LPRKES is based on a general view of the well known Feistel-Network (FN) in which we only use two rounds in an efficient and secure way, employing data-dependent cipher-keys. In the LIRKES, an extra ciphertext block is used, encrypting the one-time random cipher-key based on a signature of the whole ciphertext. The security of the presented schemes are theoretically proven and, compared to the state-of-the-art RKESs, the savings in the required computational complexity, run-time, bandwidth, and storage space are emphasized.