Searchable Encryption Using Polynomial Trapdoors for Variable Keyword Lengths
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Solution Overview
Problem
Existing searchable encryption methods face challenges in efficiently detecting keywords of varying lengths in encrypted data streams, particularly in cloud storage and network traffic, due to increased complexity and security risks associated with keyword definition and size constraints.
Innovation Solution
A method for generating trapdoors in a searchable encryption system using random elements and polynomials, allowing for the detection of keywords of any length without requiring predefined keyword sizes, ensuring security by separating the entities generating and using trapdoors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If keyword splitting is performed for each possible keyword size to enable detection of keywords of varying lengths, then detection capability is improved, but encryption complexity and traffic volume increase significantly
Solution Approach 1:
The patent applies universality by creating a single polynomial structure that can handle keywords of any length. Instead of having separate encryption processes for different keyword sizes, one universal polynomial-based trapdoor mechanism serves all keyword lengths, making the system multi-functional without increasing complexity for each specific case.
Solution Approach 2:
The patent uses parameter changes by making the polynomial degree adaptive to the keyword length. The polynomial degree parameter changes based on the actual keyword size being searched, allowing the same underlying mechanism to efficiently handle variable-length keywords without requiring separate processes for each size.
2Adaptability or versatility
If keyword splitting is performed for each possible keyword size, then detection capability is improved, but traffic volume increases
Solution Approach 1:
The universal polynomial-based trapdoor mechanism allows a single encrypted representation to support searches for keywords of any length. This eliminates the need to transmit separate encrypted data for each keyword size, thereby reducing overall traffic volume while maintaining detection capability across all sizes.
3Device complexity
If keywords are split to force uniform size, then encryption complexity is reduced, but security is compromised due to information revelation
Solution Approach 1:
The patent applies local quality by allowing each coefficient of the polynomial to encode information about specific positions in the keyword. This localized encoding ensures that only the necessary information for each position is revealed, maintaining security while keeping the encryption process manageable and avoiding the need to force uniform keyword sizes.
4Adaptability or versatility
If the entity performing search has trapdoors for almost all words, then search capability is improved, but the risk of deducing plaintext data item increases
Solution Approach 1:
The patent uses parameter changes by making the polynomial degree dynamic based on the specific search keyword length. This ensures that trapdoors are generated only when needed for specific search terms rather than pre-generating trapdoors for all possible words. The adaptive parameter approach maintains search capability while minimizing the exposure of plaintext information and reducing security risks.
Data Source
AI summary
A method for searchable encryption of a system defining a secret key and a public is provided. A data stream cipher can include n elementary data (b1, b2, . . . , bn). The method can include generation of a variate for all elementary data bj, for values of j from 1 to n, generation of an element function of the public key (gx(bj),zj) and the variate, the element being associated with a random element of a group of a bilinear environment, the element associated with the random element of the group forming first encryption data (Cj,1). The method can also include generation of a shift factor (ga.zj−1) function of the variate and the public key, and associated with the random element of the group, the shift factor representing a position of the monomial in the encrypted stream, the shift factor associated with the random element of the group forming second encryption data. The data stream cipher can include the first and second encryption data for all values of j from 1 to n.