The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 23, 2010
Filed:
Aug. 15, 2001
Paul C. Kocher, San Francisco, CA (US);
Joshua M. Jaffe, San Francisco, CA (US);
Benjamin C. Jun, Palo Alto, CA (US);
Paul C. Kocher, San Francisco, CA (US);
Joshua M. Jaffe, San Francisco, CA (US);
Benjamin C. Jun, Palo Alto, CA (US);
Cryptography Research, Inc., San Francisco, CA (US);
Abstract
Methods and apparatuses are disclosed for improving DES and other cryptographic protocols against external monitoring attacks by reducing the amount (and signal-to-noise ratio) of useful information leaked during processing. An improved DES implementation of the invention instead uses two 56-bit keys (Kand K) and two 64-bit plaintext messages (Mand M), each associated with a permutation (i.e., KP, KP and MP, MP) such that KP{K} XOR KP {K} equals the 'standard' DES key K, and MP{M} XOR MP{M} equals the 'standard' message. During operation of the device, the tables are preferably periodically updated, by introducing fresh entropy into the tables faster than information leaks out, so that attackers will not be able to obtain the table contents by analysis of measurements. The technique is implementable in cryptographic smartcards, tamper resistant chips, and secure processing systems of all kinds.