Smart cards provide an effective tool for portable safe hardware storage of secret keys critically needed in many recent multimedia applications such as real time access control, software license management. Smart cards are mainly reliable because of their distinctive features of tamper-resistant packaging and low cost. However, with their computationally limited resources, smart cards cannot process large data blocks as fast as the host may need.This book introduces RKES (Remotely Keyed Encryption Schemes) which are greatly useful in solving the vital problem of how to do bulk encryption and decryption for high-bandwidth applications (like multimedia and video encryption) in a way that takes advantage of both the superior power of the host and the superior security of the smart card. In this way, a novel Length Preserving / Length Increasing (LP/LI) RKESs are proposed. The proposed (LP/LI) RKESs need strong pseudorandom permutations (PRP) as their basic building block, so we introduce two new symmetric key block ciphers, with variable block and key lengths, referred to as NMSFC and PATFC which are Fesitel network type ciphers, appropriate for hardware and software implementations.