AES software implementations on ARM7TDMI

Information security on small, embedded devices has become a necessity for high-speed business. ARM processors are the most common for use in embedded devices. In this paper, we analyze speed and memory tradeoffs of AES, the leading symmetric cipher, on an ARM7TDMI processor. We give cycle counts as well as RAM and ROM footprints for many implementation techniques. By analyzing the techniques, we give the options we found which are the most useful for certain purposes. We also introduce a new implementation of AES that saves ROM by not explicitly storing all the SBOX data.