PUF Memory Readout Scrambling for Side-Channel Leakage Reduction
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Solution Overview
Problem
Existing memory-based PUF systems face significant side-channel leakage during the readout process, particularly due to power consumption variations, which can reveal sensitive information about the cryptographic key, making it difficult to maintain key confidentiality.
Innovation Solution
The system employs a scrambled readout of memory content over the memory interface, combined with encryption and decryption units to securely read and write the memory content, thereby reducing side-channel leakage by obscuring the hamming weight information and using a second PUF for generating random permutations to thwart attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory content is read out in a standard sequential order, then the readout process is simple and fast, but side-channel leakage occurs that reveals hamming weight information and compromises cryptographic key security
Solution Approach 1:
The memory content is divided into multiple segments or blocks, and the readout process reads these segments in a scrambled而非sequential order. This segmentation approach breaks the direct correlation between memory position and hamming weight leakage, thereby improving cryptographic security while managing readout complexity through structured segmentation.
Solution Approach 2:
Before the actual readout of memory content, a scrambling operation is performed preliminarily to randomize the order of memory locations. This preliminary scrambling action ensures that when the readout occurs, the hamming weight information cannot be directly correlated with specific memory positions, thus preventing side-channel attacks while establishing a secure readout framework.
2Reliability
If helper data is stored in non-volatile memory for error correction, then key reproduction accuracy is improved, but the system becomes vulnerable to physical attacks such as probing and side-channel analysis
Solution Approach 1:
A cryptographic hash function is introduced as an intermediary between the helper data and the key reproduction process. The helper data is hashed before being used in key generation, which ensures that even if an attacker gains access to the stored helper data, they cannot directly derive the cryptographic key. This intermediary hashing operation maintains key reproduction accuracy while providing security against physical attacks and side-channel analysis.
3Measurement precision
If error correction is performed using traditional methods, then key derivation accuracy is maintained, but information leakage occurs during the error correction process that can be exploited by attackers
Solution Approach 1:
The error correction process is designed to work with the inherent noise and variations in PUF output rather than trying to eliminate them completely. By using error correction codes that are specifically tailored to the PUF's error characteristics, the system converts the potentially harmful variations into manageable parameters. This approach maintains key derivation accuracy while minimizing information leakage, as the error correction process itself becomes part of the security mechanism rather than a vulnerability.
Data Source
Figure 1a~1b
Figure 2
Figure 3a~3b
AI summary
An electronic system 100 for generating a cryptographic key, the system comprising: a memory 110 used as a physically unclonable function, the memory being writable, volatile and configured such that upon each powering-up of the memory the memory settles into a memory content which depends upon at least partially random physical characteristics of the memory, the memory being accessible through a memory interface, and a key derivation unit 150 configured to derive the cryptographic key from the memory content into which the memory settled, wherein the electronic system for generating a cryptographic key further comprises, a memory read-out unit connected to the memory through the memory interface and to the key derivation unit, the memory read-out unit comprising an address scrambler 140 for retrieving the memory content over the memory interface in a scrambled order.