Forward-Secure Logging Device with Dynamic Entry Placement
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Solution Overview
Problem
Existing logging devices are vulnerable to attacks that compromise the integrity of log messages, as attackers can identify and modify or delete specific log entries with relative ease.
Innovation Solution
A logging device that encrypts log messages using evolving keys and generates authentication codes, combined with a position determination device that randomly selects log entry locations, ensuring each log entry has a uniform probability of being stored at any location, and includes the creation of dummy entries to detect tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If log entries are stored in sequential locations, then verification is simplified, but attackers can easily identify and modify specific log entries
Solution Approach 1:
The patent implements dynamic log entry placement where the storage location of each log entry is determined by a pseudo-random function of its sequence number rather than fixed sequential positions. This dynamic mapping prevents attackers from predicting where specific log entries are stored, thereby protecting log integrity while maintaining verification capability through the deterministic nature of the pseudo-random function
Solution Approach 2:
The patent introduces an intermediary verification mechanism that uses authentication codes and pseudo-random location mapping to bridge the gap between secure storage and verification. The intermediary layer allows verification without requiring direct knowledge of physical storage locations, thus protecting log integrity while simplifying the verification process
2Reliability
If encryption keys are reused for multiple log entries, then processing is faster, but security is compromised as one key compromise exposes all entries
Solution Approach 1:
The patent segments the encryption key space by deriving individual encryption keys for each log entry from a master secret using a pseudo-random function of the entry's sequence number. This segmentation ensures that compromise of one entry's key does not expose other entries, maintaining security while avoiding the overhead of storing multiple independent keys by computing them on-demand
Solution Approach 2:
The patent changes the encryption key parameter dynamically based on the log entry's sequence number. Each log entry is encrypted with a unique key derived from the master secret and its position, providing forward security and preventing key reuse vulnerabilities while maintaining processing efficiency through deterministic key derivation
3Reliability
If dummy entries are added to detect tampering, then security against attacks improves, but storage space and verification complexity increase
Solution Approach 1:
The patent creates cryptographic copies of authentication information distributed across log entries rather than storing separate dummy entries. Each log entry contains authentication codes that serve as verified copies of integrity information, enabling tamper detection without requiring additional dummy storage space
Solution Approach 2:
The patent makes each log entry multi-functional by incorporating authentication codes and position verification information within the same storage structure used for actual log data. This universality allows the system to perform both logging and tamper detection functions without requiring separate dummy entries, thus avoiding additional storage overhead
Data Source
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AI summary
The invention relates to a logging device configured to store log messages, comprising a storage device having a plurality of log entry locations which can be ordered as a sequence and an encryption device configured to generate the encrypted log messages from log messages. Furthermore, the logging device comprises an authentication code generator configured to generate an authentication code from the encrypted log message. A key evolving device and a state storage device configured to store state variables for use by the encryption device, the authentication code generator and/or the key evolving device are also provided. Furthermore, the invention relates to a verification device configured to verify log entries stored in log entry locations of the storage device. The invention also relates to a method for storing log entries in log entry locations of a storage device of a logging device as well as to a method for verifying the integrity of log entries stored in log entry locations of a storage device.