Dynamic Password Challenge Randomization
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Solution Overview
Problem
Existing password challenge mechanisms in embedded systems are susceptible to malicious hacks as the method used to generate passwords and verification words remains constant across power cycles and different systems, allowing malicious users to measure and replicate signal patterns for unauthorized access.
Innovation Solution
A method involving the generation of scramble control codes through random number shifting and subset selection to dynamically randomize password and verification word sub-words, altering comparison order, inserting delays, and performing dummy comparisons, thereby changing the pattern of signal pulses or spikes with each challenge, making it difficult for malicious users to replicate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant password challenge mechanism is used across power cycles and systems, then ease of operation is improved, but security is worsened due to predictable signal patterns
Solution Approach 1:
The patent applies dynamics by making the password challenge mechanism variable rather than static. A randomizer generates different challenge patterns for each power cycle, and within each challenge, the order of sub-word comparisons is dynamically randomized. This ensures that signal patterns change with each operation, preventing malicious users from capturing and replicating predictable patterns while maintaining operational simplicity through automated randomization.
Solution Approach 2:
The patent changes parameters by introducing randomization variables into the password challenge process. The randomizer changes the challenge pattern parameters between power cycles, and the comparison circuit changes the sub-word comparison order parameters during each challenge. This parameter variation creates unique signal patterns for each operation, enhancing security without complicating the user interface.
2Reliability
If multiple sub-word comparisons are performed, then security is improved through increased complexity, but device complexity is worsened
Solution Approach 1:
The patent segments the password into multiple sub-words that are stored in separate registers. The comparison process is divided into multiple stages where different subsets of sub-words are compared in randomized orders. This segmentation allows security to be enhanced through multiple comparison operations while managing device complexity by organizing the process into modular stages controlled by randomizer-generated patterns.
Solution Approach 2:
The patent uses dynamic randomization to control which sub-words are compared and in what order, rather than using a fixed comparison sequence. The randomizer generates challenge patterns that dynamically determine the comparison sequence, allowing multiple sub-word comparisons to be performed with varying patterns across different challenges, thereby enhancing security without requiring a permanently complex comparison architecture.
3Reliability
If signal patterns are made unique through randomization, then security is improved, but ease of operation is worsened due to increased complexity
Solution Approach 1:
The system performs self-service by automatically generating random challenge patterns and executing the randomized comparison process without requiring user intervention. The randomizer and comparison circuit work autonomously to create unique signal patterns for each password challenge, maintaining ease of operation from the user perspective while enhancing security through automated complexity.
Data Source
AI summary
A method of operating an electronic device includes generating scramble control codes. The scramble codes are generated by generating a random number, shifting the random number to produce a shifted random number, generating control signals by selecting different subsets of the shifted random number, and generating scramble control words by selecting different subsets of the random number based upon the control signals. The method further includes receiving a password comprised of sub-words and scrambling those sub-words according to the scramble control codes, retrieving a verification word comprised of sub-words and scrambling those sub-words according to the scramble control codes, and comparing the scrambled sub-words of the password to the scrambled sub-words of the verification word to thereby authenticate an external device that provided the password.