US 7,599,491 B2
	Method for strengthening the implementation of ECDSA against power analysis
Robert J. Lambert, Cambridge (Canada)
Assigned to Certicom Corp., Mississauga (Canada)
Filed on Apr. 11, 2002, as Appl. No. 10/119,803.
Application 10/119803 is a continuation in part of application No. 09/900959, filed on Jul. 10, 2001, granted, now 7,092,523.
Application 09/900959 is a continuation in part of application No. PCT/CA00/00021, filed on Jan. 11, 2000.
Application PCT/CA00/00021 is a continuation in part of application No. PCT/CA00/00030, filed on Jan. 14, 2000.
Claims priority of application No. 2258338 (CA), filed on Jan. 11, 1999; and application No. 2259089 (CA), filed on Jan. 15, 1999.
Prior Publication US 2003/0194086 A1, Oct. 16, 2003
Int. Cl. H04K 1/00 (2006.01); H04L 9/00 (2006.01); G06F 1/26 (2006.01); G08B 29/00 (2006.01)

U.S. Cl. 380—30  [380/28; 726/36]

22 Claims

1. A computer-implemented method of masking a cryptographic operation comprising generation of a signature r, s in a public key elliptic curve cryptographic system, said operation utilizing both a long term private key d and a short term private key k, wherein r=Kx mod n with K being a public key derived from the short term private key k and a generating point G, Kx being the representation of the x coordinate of the key K and n the order of the generating point G, and wherein s=1/k (e+dr) with e being a hash of the message to be signed and d being the long term private key, said method comprising the steps of: applying masking values to each of said long term private key and short term private key during at least a portion of said cryptographic operation to produce a result, said result corresponding to that obtained without application of said masking values whereby observation of said private keys is inhibited by said masking values during said cryptographic operation.