Auditing Shredding Data via Segmented MAC Keys
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Solution Overview
Problem
Current paper sheet processing systems lack sufficient security measures to prevent falsification of processed data, such as count information, which is critical for ensuring the integrity of paper sheet processing operations.
Innovation Solution
A method is introduced that utilizes a pair of MAC generation keys, one stored on an IC card and the other on the paper sheet processing device, to generate and verify message authentication codes (MACs) for count information, ensuring that any discrepancies in count information are detected and preventing falsification by using a private and public key encryption system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single MAC generation key is stored in the paper sheet processing device, then the device complexity is reduced, but the security against falsification of count information is insufficient
Solution Approach 1:
The MAC generation key is segmented into two parts: a first key stored in the paper sheet processing device and a second key stored in the IC card. This segmentation ensures that neither key alone can generate a valid MAC, thereby enhancing security against falsification while distributing key management responsibilities across different components.
Solution Approach 2:
The IC card acts as an intermediary that stores the second MAC generation key and provides it to the auditing device when needed. This intermediary role allows the system to maintain security by keeping the second key separate from the processing device while enabling audit verification when the IC card is present.
2Reliability
If MAC verification is performed without an IC card, then the ease of operation is improved, but the security against falsification is compromised
Solution Approach 1:
The system requires the IC card to be inserted before audit verification can occur, preventing any attempt at falsification before it can happen. The presence of the IC card with the second key is a preliminary condition that must be satisfied, ensuring that count information cannot be falsified during the audit process.
3Reliability
If count information is transmitted in plaintext, then the ease of operation is improved, but the security against falsification is reduced
Solution Approach 1:
The system replaces physical security measures (such as secure hardware compartments) with cryptographic mechanisms. Count information is transmitted in plaintext, but the MAC value provides cryptographic protection against falsification, substituting mechanical security with mathematical security through the MAC verification process.
Data Source
AI summary
According to one embodiment, there is provided a method for auditing shredding data including first count information in a system for auditing shredding data. The audit method includes causing a paper sheet processing apparatus to generate a first MAC based on the first count information using a first MAC generation key, causing the paper sheet processing apparatus to transmit the first count information and the first MAC to a first computing unit, causing the first computing unit to obtain second count information based on the first MAC using a second MAC generation key, causing the first computing unit to compare the first count information and the second count information, and determining an audit result.