Cryptographic Processor Circuit Camouflage for Reverse Engineering Resistance

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Solution Overview

Problem

Reverse engineering of integrated circuits poses a significant threat to the semiconductor industry, as attackers can steal and replicate circuit designs, and existing methods to thwart this are either costly, time-consuming, or compromise cryptographic security.

Innovation Solution

Implementing a cryptographic processor with a processing circuit that performs an iterated cryptographic algorithm, a controller to apply multiple iterations, and a transformation circuit using circuit camouflage techniques to hinder reverse engineering, by adding transformations to encryption or decryption blocks and key scheduling processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If circuit camouflage techniques are applied to protect cryptographic algorithms, then reverse engineering resistance is improved, but device complexity increases

Engineering Contradiction:

Improvereverse engineering resistanceVSAvoidcircuit structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a transformation circuit as an intermediary component between the cryptographic processing circuit and the external interface. This transformation circuit applies circuit camouflage techniques by inserting dummy circuits and transforming the appearance of critical cryptographic operations, thereby protecting the core algorithm without fundamentally redesigning the entire system architecture.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cryptographic processor is divided into distinct functional modules: a cryptographic processing circuit for core operations, a transformation circuit for camouflage operations, and a controller for coordination. This segmentation allows the camouflage functionality to be added as a separate layer without complicating the core cryptographic logic.

Inventive Principle:

Principle #1Segmentation

2Reliability

If multiple iterations of round function are applied, then cryptographic security is improved, but processing time increases

Engineering Contradiction:

Improvecryptographic securityVSAvoidmessage processing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The transformation circuit performs preliminary camouflage transformations on the input message before it enters the iterative round function processing. By pre-processing and camouflaging the input, the system reduces the effective processing time required for each iteration while maintaining the security benefits of multiple iterations through the controller's coordination of the cryptographic operations.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9806881B2Cryptographic processor, method for implementing a cryptographic processor and key generation circuit

Publication Date: 2017.10.31 INFINEON TECHNOLOGIES AG

AI summary

A cryptographic processor is described comprising a processing circuit configured to perform a round function of an iterated cryptographic algorithm, a controller configured to control the processing circuit to apply a plurality of iterations of the round function on a message to process the message in accordance with the iterated cryptographic algorithm and a transformation circuit configured to transform the input of a second iteration of the round function following a first iteration of the round function of the plurality of iterations and to supply the transformed input as input to the second iteration wherein the transformation circuit is implemented using a circuit camouflage technique.