Sequential Log Security via Time-Constraint Verification
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Solution Overview
Problem
Existing methods for securing logs, such as digital signing and append-only storage, are inadequate in preventing and detecting tampering attacks, particularly branching or forking attacks, which can create parallel sequences that are difficult to distinguish from the original, even for outsiders.
Innovation Solution
Implementing time constraints on entries into sequential data structures, using cryptographic hashes to link blocks, and employing the Guardtime KSI signature system to timestamp and verify entries, ensuring that each block's timestamp and signature are irrefutable and verifiable, making it impractical for attackers to create fake branches without being detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital signing or append-only storage is used to secure logs, then basic integrity is improved, but vulnerability to branching attacks worsens
Solution Approach 1:
The patent applies preliminary action by embedding a timestamp from a trusted time source into each log entry before the entry is committed to the log structure. This timestamp serves as a pre-established trust anchor that prevents attackers from creating valid fake branches, because any fraudulent entry would require a timestamp from the trusted source that corresponds to a time when the attacker did not possess the necessary cryptographic keys. This preliminary embedding of time-trust information resolves the contradiction by maintaining log integrity while preventing branching attacks.
2Reliability
If digital signatures are applied to log entries, then authenticity is improved, but ease of verification worsens
Solution Approach 1:
The patent extracts the trust verification function from the log entry itself by separating the timestamp (which provides authenticity) from the log entry content. The timestamp is obtained from a trusted external time source and embedded in the entry, while the entry content remains separate. This allows verification to focus on checking the timestamp against the trusted time source rather than verifying entire digital signatures on each entry, thereby maintaining authenticity while simplifying verification.
3Object-affected harmful factors
If time constraints are imposed on log entries, then resistance to branching attacks is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary trusted time source that provides timestamps to log entries. This intermediary serves as a mediator between the log system and the trust framework, eliminating the need for complex cryptographic key management and signature verification infrastructure within the log system itself. The trusted time source acts as a centralized authority that simplifies the overall system architecture while providing strong resistance to branching attacks through its time-based trust model.
Data Source
AI summary
A log, comprising a sequence of temporally ordered digital entries, is authenticated by entering a new entry into the log only after expiration of a minimum time interval. A digital signature and timestamp are generated for each entry in the log and are included in each respective entry. In a validity verification phase, the timestamp of at least one of the entries is examined to determine whether it indicates entry into the log at a time relative to a preceding entry in the log after less than an expected minimum time interval. If so, a remedial action is taken.