ThesearetheproceedingsofCHES2002, theFourthWorkshoponCryptographic Hardware and Embedded Systems. After the ?rst two CHES Workshops held in Massachusetts, and the third held in Europe, this is the ?rst Workshop on the West Coast of the United States. There was a record number of submissions this year and in response the technical program was extended to 3 days. As is evident by the papers in these proceedings, there have been again many excellent submissions. Selecting the papers for this year's CHES was not an easy task, and we regret that we could not accept many contributions due to the...