Feedback Shift Register Integrity Violation Detection
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Solution Overview
Problem
Feedback shift registers used in security applications are vulnerable to integrity violations, which can lead to deterministic output sequences and compromise cryptographic security, as existing technologies lack effective online monitoring and detection mechanisms.
Innovation Solution
An apparatus and method incorporating an integrity violation detector that determines whether input or output sequences of feedback shift registers are constant or non-constant, using an online tester to count runs of bits and detect integrity violations, and outputs alerts or countermeasures when predetermined thresholds are exceeded, thereby protecting against tampering and ensuring the integrity of pseudorandom sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If feedback shift registers are used in security applications, then cryptographic functions are enabled, but vulnerability to integrity violations increases
Solution Approach 1:
The patent implements a monitoring mechanism that continuously observes the output sequence of the feedback shift register and feeds back integrity verification results. The online tester checks whether the output sequence maintains expected statistical properties (non-constant, non-deterministic characteristics) and triggers alerts or countermeasures when integrity violations are detected, creating a closed-loop security system.
Solution Approach 2:
The patent introduces an intermediary monitoring component (online tester) that sits between the feedback shift register and the cryptographic processing unit. This intermediary continuously analyzes the register output for integrity violations without interfering with the normal cryptographic operations, enabling detection of tampering or faults while maintaining system functionality.
2Reliability
If online monitoring is implemented, then integrity violation detection is enabled, but device complexity increases
Solution Approach 1:
The monitoring system is designed to autonomously perform integrity checks on the feedback shift register output without requiring external intervention. The online tester automatically analyzes sequence properties, compares them against expected characteristics, and triggers appropriate responses (alerts or countermeasures) based on detected anomalies, enabling self-diagnosis and self-protection.
Solution Approach 2:
The patent monitors statistical parameters of the output sequence (such as bit distribution, run lengths, and periodicity) to detect integrity violations. By tracking changes in these parameters over time and comparing them against expected ranges for secure operation, the system can identify tampering or faults without requiring complex structural modifications to the underlying cryptographic components.
3Measurement precision
If constant sequence detection is implemented, then integrity violations are detected, but false positives may occur
Solution Approach 1:
The monitoring system applies multiple detection criteria and threshold checks rather than relying on a single constant-sequence test. By examining multiple statistical properties of the output sequence and requiring multiple conditions to be met before triggering an alert, the system reduces false positives while maintaining sensitivity to actual integrity violations.
Solution Approach 2:
The system establishes baseline statistical characteristics of normal operation beforehand and uses these pre-determined parameters to guide real-time detection. By pre-defining expected sequence properties and detection thresholds based on the specific feedback shift register configuration and cryptographic application, the system minimizes false alarms while maintaining accurate violation detection.
Data Source
AI summary
An apparatus for detecting integrity violation includes a feedback shift register including a plurality of registers connected in series, and a feedback function unit connected between an output of a number of the registers and an input of at least one of the registers. The apparatus further includes an integrity violation detector adapted to determine as to whether a sequence of values at an input or output of at least one of the registers, or a logic combination thereof, is a non-constant sequence or a constant sequence. The apparatus is further adapted to output an indication that the feedback shift register is in an integral state if the sequence of values is a non-constant sequence, or to output an indication that the feedback shift register is subjected to an integrity violation if the sequence of values is a constant sequence.