Secure Boot Counter Isolation Against Glitch Attacks
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Solution Overview
Problem
Existing solutions for secure booting of processing devices do not adequately protect boot codes and critical data from external attacks, particularly during the boot sequence, and there is a risk of glitch attacks that can compromise the security of these codes and data.
Innovation Solution
A method and device that utilize a monotonic counter and protection circuit to increment a counting value, compare it with reference values, and change it to a specific value if it is smaller, ensuring that boot codes and data are only accessible at specific isolation levels, thereby preventing unauthorized access and countering glitch attacks by forcing the counting value to a secure level after a predetermined time during the boot sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing solutions are used to make boot codes immutable, then boot codes are protected from external attacks, but access to boot codes and critical data during booting remains vulnerable to glitch attacks
Solution Approach 1:
The patent applies preliminary action by setting up a monotonic counter and protection circuit before the boot sequence begins. The counter is initialized to a first value and automatically increments during boot, with the protection circuit pre-configured to compare the counting value against reference values and force updates to isolation levels. This preliminary setup ensures that even if glitch attacks occur during booting, the counting mechanism is already in place to detect and respond to unauthorized access attempts, thereby enhancing protection beyond simple immutability.
2Reliability
If boot codes are made immutable, then security is improved, but the complexity of the protection mechanism increases
Solution Approach 1:
The patent segments the protection mechanism into distinct functional components: a monotonic counter for tracking boot progression, a protection circuit for monitoring and enforcing security policies, and reference value storage for isolation levels. This segmentation allows each component to perform its specific function efficiently without requiring the entire system to be overly complex. The counter simply increments, the protection circuit performs comparisons and forced updates, and reference values are stored separately, creating a modular architecture that balances security with manageable complexity.
3Reliability
If the counting value is continuously monitored and updated, then protection against glitch attacks is enhanced, but the processing time during boot sequence increases
Solution Approach 1:
The patent implements periodic action by having the protection circuit monitor the counting value at specific intervals during the boot sequence rather than continuously. The counter increments periodically as the boot progresses through different stages, and the protection circuit compares the counting value against reference values at these periodic checkpoints. This periodic monitoring approach maintains security against glitch attacks while avoiding the time penalty of continuous monitoring, as the system only performs security checks at predetermined moments in the boot process.
Data Source
AI summary
A method includes protecting a boot sequence of a processing device by incrementing a counting value generated by a monotonic counter, then a first time period after the beginning of the boot sequence, comparing, by the protection circuit, the counting value with a first reference value, and, if the counting value is smaller than the first reference value, changing, by the protection circuit, the counting value to the first reference value.