US 7,319,750 Bl *Jan. 15, 2008
(54) DIGITAL CIRCUIT APPARATUS AND
METHOD FOR ACCELERATING
PRELIMINARY OPERATIONS FOR
(75) Inventors: Mahesh S. Maddury, Santa Clara, CA
(US); Kenneth J. Tomei, Sunnyvale,
CA (US); Justina Provine, San Jose,
(73) Assignee: Cisco Technology, Inc., San Jose, CA (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 1113 days.
This patent is subject to a terminal disclaimer.
(21) Appl. No.: 10/212,936
(22) Filed: Aug. 5, 2002
Related U.S. Application Data
(63) Continuation of application No. 10/196,829, filed on Jul. 16, 2002, now Pat. No. 7,187,770.
A digital circuit apparatus and method for cryptographic data processing includes steps and means for determining a first modulus having up to a first number of binary digits. A large integer is received which has up to a second number of binary digits that is greater than the first number of binary digits. The first modulus and the large integer are sent to a first processor for computing a first residue of the large integer modulo the first modulus. Before the first processor finishes computing the first residue, the first modulus is also sent to a second processor for computing a second residue of two raised to a power of twice the first number of binary digits modulo the first modulus. The first residue and the second residue are used as input to a third processor that computes a cryptographic result based on the large integer.