Patent ID: 7995752

Claim:
A method of computing a short term public key for an elliptic curve digital signature protocol, the method comprising: in a cryptographic processor and computational unit: receiving a message and a digital signature, the digital signature comprising at least a first scalar signature component s; hashing the message to compute a second scalar, -e; obtaining a first point that is a group element P, of the elliptic curve, corresponding to the first scalar, and a second point that is a long term public key Q corresponding to the second scalar; representing each scalar in a binary format comprising bit positions; windowing each represented scalar; initializing an accumulator value to 0; for each bit position of the binary format from the most significant bit position to the least significant bit position: doubling the accumulator value; and for each represented scalar, if the bit position marks the end of a window of length i, then adding to the accumulator, the product, from a precomputed table, of the bit string represented in the window and the point corresponding to the scalar, wherein the precomputed table comprises products of the point corresponding to the scalar and all bit strings of length i ending in a nonzero value, and outputting the accumulator value as the short term public key.