OCAPI: architecture of a VLSI coprocessor for the GCD and the extended GCD of large numbers

Various algorithms for finding the greatest common divisor (GCD) and extended GCD of very large integers are explored. In particular, the tradeoff between computation time and area is examined. Two of the algorithms, from which the method for deriving variants is straightforward, are detailed. Then the architecture of a VLSI processor dedicated to GCD as well as multiply, divide, square root, etc. of very large numbers (>600 decimal digits), using an internal radix 2 redundant representation and supporting multiple precision, is described