RECENT DEVELOPMENTS IN ELECTRONIC CIRCUITRY AND THEIR EFFECTS ON THE IMPLEMENTATION OF SUBSTITUTION-PERMUTATION BLOCK CODES
John R. Michener · Cryptologia · 1988
Recent developments in programmable electronic circuitry allow the creation of readily modified transposition boxes. These devices, such as the user programmable gate array first introduced by Xilinix Inc., allow the definition of transposition tables to be readily changed - merely by changing the configuration program read into the internal memory of the device. The use of such devices in conjunction with microprocessors with substantial on chip or closely coupled cache memory allows the construction of flexible, relatively inexpensive, cryptographic engines of very high speed and security.