Protecting look up tables by mixing code and operations

US9189425B2 · kind B2 · utility

Assignee

• Apple Inc. · US

Inventors

• Augustin J. Farrugia · Cupertino, US
• Benoit Chevallier-Mames · Paris, FR
• Bruno Kindarji · Paris, FR
• Mathieu Ciet · Paris, FR
• Thomas Icart · Paris, FR

Key dates

• Filing date: Oct 31, 2011
• Grant date: Nov 17, 2015
• Expiry date: Aug 20, 2034

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L2209/24
• WIPO field: Control
• WIPO sector: Instruments

Abstract

In the field of computer enabled cryptography, such as a cipher using lookup tables, the cipher is hardened against an attack by a protection process which obscures the lookup tables using the properties of bijective functions and applying masks to the tables' input and output values, for encryption or decryption. This is especially advantageous in a “White Box” environment where an attacker has full access to the cipher algorithm, including the algorithm's internal state during its execution. This method and the associated computing apparatus are useful for protection against known attacks on “White Box” ciphers, by obfuscating lookup table data, thereby increasing the cipher's complexity against reverse engineering and other attacks.