Message Authentication Code Generation via DPA-Safe Key Transformation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for generating message authentication codes are vulnerable to side channel attacks, such as DPA, which compromise secret keys used in symmetric block ciphers and hash algorithms, requiring complex and resource-intensive protection measures.

Innovation Solution

The solution involves relocating the protection problem to a DPA-safe AES operation, where a generated key is produced using a cryptographic encryption algorithm or hash calculation, and then used to generate the message authentication code, thereby shifting the susceptibility to side channel attacks to the key generation process rather than the MAC calculation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional MAC calculation methods are used, then the MAC generation is simple and efficient, but the system is vulnerable to side channel attacks such as DPA

Engineering Contradiction:

Improvesecurity against side channel attacksVSAvoidcomplexity of protection measures

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The MAC calculation process is segmented into two distinct phases: a protected key generation phase using DPA-safe AES operation, and an unprotected MAC computation phase. This segmentation allows the critical key handling portion to be protected while keeping the overall system efficient.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The secret key is pre-processed through a protected AES encryption operation with a random value before being used in the MAC calculation. This preliminary protective action ensures that the actual secret key never directly participates in the unprotected MAC computation, preventing DPA attacks.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If DPA protection measures are applied to MAC calculation, then security against side channel attacks is improved, but resource consumption and complexity increase

Engineering Contradiction:

Improvesecurity against DPA attacksVSAvoidprocessor resource consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

DPA protection is applied locally only to the key generation portion of the MAC calculation, not to the entire MAC computation process. The AES key generation uses protected operations while the subsequent MAC calculation can use efficient unprotected operations, optimizing resource usage.

Inventive Principle:

Principle #3Local quality

3Productivity

If the secret key is directly used in MAC calculation, then the MAC generation is efficient, but the key becomes vulnerable to extraction through side channel attacks

Engineering Contradiction:

ImproveMAC generation speedVSAvoidsusceptibility to side channel attacks

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

An intermediary protected AES encryption operation is introduced between the secret key and the MAC calculation. The secret key is transformed through this intermediary process into a protected form that can be used in MAC calculation without exposing the original key to side channel analysis.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12184770B2Apparatus and method for producing a message authentication code

Publication Date: 2024.12.31 INFINEON TECHNOLOGIES AG

AI summary

An apparatus for producing a message authentication code based on a first message and an original key is provided. The apparatus includes a key generator configured to produce a generated key based on the original key and the first message. Furthermore, the apparatus includes a message authentication code generator configured to produce the message authentication code based on the generated key and the first message.