Search Device Auxiliary Tag Filtering for Encryption Access Control
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Solution Overview
Problem
Existing searchable encryption techniques require long search processing times and lack flexible access control, with the technique in Non-Patent Literature 2 being unable to perform cryptographic access control.
Innovation Solution
A search device with an auxiliary collation unit to determine the existence of an auxiliary tag corresponding to a query and a main collation unit to specify an encryption tag based on attribute information, reducing unnecessary processing and enabling flexible access control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If searchable encryption techniques using public key encryption or inner-product predicate encryption are used, then cryptographic access control is achieved, but search processing time becomes long
Solution Approach 1:
The search processing is divided into two independent stages: auxiliary tag matching (fast filtering) and encryption tag verification (security verification). This segmentation allows the system to quickly eliminate non-matching queries before performing time-consuming cryptographic operations, thereby reducing overall search processing time while maintaining access control security.
Solution Approach 2:
Auxiliary tags are pre-computed and stored alongside encrypted data, enabling the system to perform preliminary filtering before the main search operation. This preliminary action of matching auxiliary tags against search keywords allows the system to quickly determine whether a search query should proceed to the cryptographic verification stage, significantly reducing unnecessary processing time.
2Productivity
If the searchable encryption technique from Non-Patent Literature 2 is used, then search processing speed is improved, but cryptographic access control capability is lost
Solution Approach 1:
The search process is segmented into a fast auxiliary tag matching phase (similar to Non-Patent Literature 2 for speed) and a cryptographic encryption tag verification phase (providing access control security). This segmentation allows the system to achieve both high processing speed for filtering and robust cryptographic access control for authorization.
Solution Approach 2:
Encryption tags serve as an intermediary mechanism that bridges the gap between fast search processing and secure access control. These tags contain encrypted access policies that are verified cryptographically after auxiliary tag matching, enabling the system to maintain both speed and security without relying on slower public key encryption for every search operation.
3Loss of time
If auxiliary tag storage and verification is implemented, then search processing time is reduced, but device complexity increases
Solution Approach 1:
The auxiliary tag structure is designed to be multi-functional: it serves both as a fast filtering mechanism for reducing search processing time and as part of the access control verification chain. By making the auxiliary tags serve multiple purposes, the system reduces overall complexity compared to having separate independent mechanisms for filtering and access control.
Data Source
AI summary
A search device (60) determines whether or not an auxiliary tag AT corresponding to an auxiliary query AQ obtained by conversion of a keyword exists, among auxiliary tags AT stored in an auxiliary tag storage unit (632) and obtained by conversion of a search word. When it is determined that the auxiliary tag AT corresponding to the auxiliary query AQ exists, the search device (60) specifies an encryption tag ET corresponding to a search query SQ being set with attribute information x indicating an attribute of a user, and the keyword, among encryption tags ET stored in an encryption tag storage unit (633) and being set with an access condition v indicating an accessible attribute, and the search word.