Dynamic Trapdoor Generation for Encrypted Keyword Search
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Solution Overview
Problem
Existing searchable encryption methods are vulnerable to offline and online dictionary attacks due to the use of static trapdoors for keywords, leading to potential brute force attacks by misfeasors.
Innovation Solution
A method that generates multiple different trapdoors for each keyword, changing dynamically with each search, and verifies these trapdoors against encrypted keywords stored in a database, eliminating the one-to-one mapping and reducing the risk of guessing attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If static trapdoors are used for keyword searching in encrypted databases, then search operations can be performed efficiently, but the system becomes vulnerable to offline and online dictionary attacks
Solution Approach 1:
The patent transforms static trapdoors into dynamic trapdoors that change with each search operation. Instead of using a fixed trapdoor for a given keyword, the system generates different trapdoors dynamically based on the search context, making each search operation unique and preventing attackers from using pre-computed dictionary attacks. This dynamic approach maintains search efficiency while eliminating the security vulnerability of static trapdoors.
Solution Approach 2:
The patent changes the parameters of trapdoor generation by incorporating additional variables such as search identifiers, timestamps, or random values into the trapdoor computation process. This parameter change ensures that the same keyword produces different trapdoors in different search contexts, thereby preventing dictionary attacks while maintaining the ability to perform efficient searches over encrypted data.
2Reliability
If multiple different trapdoors are generated for each keyword, then security against guessing attacks is improved, but the complexity of the search system increases
Solution Approach 1:
The patent implements a universal trapdoor generation mechanism that can produce multiple different trapdoors from a single keyword using a deterministic algorithm. This multi-functional approach allows the same keyword to generate various trapdoors based on different input parameters (such as search IDs or random values), providing enhanced security without requiring separate trapdoor storage for each possible trapdoor variant. The system manages complexity by using a single generation algorithm rather than multiple separate trapdoor structures.
3Object-affected harmful factors
If dynamic trapdoors are used instead of static trapdoors, then offline dictionary attacks are prevented, but the computational overhead for generating trapdoors increases
Solution Approach 1:
The patent employs preliminary action by pre-computing and storing hash values of keywords in a secure manner before actual search operations. When a search is performed, the system uses these pre-computed values combined with dynamic parameters to generate trapdoors efficiently. This preliminary preparation reduces the computational overhead during actual search operations while maintaining the security benefits of dynamic trapdoors against offline dictionary attacks.
Data Source
AI summary
The present invention relates to a computer-implemented method, system and computer readable medium for searching over encrypted keywords in a database. The method includes the steps of generating at least one keyword, generating a plurality of different encrypted keywords corresponding to the keyword, storing the at least one encrypted keyword in the database, generating a plurality of different trapdoors for the keyword, verifying the plurality of different trapdoors with the plurality of different encrypted keywords corresponding to the keyword, and determining the keyword is found if the plurality of different trapdoors match with one the encrypted keyword corresponding to the keyword, otherwise determining the keyword is not found.