Data-oblivious Subarray Copying via Index Mapping
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Solution Overview
Problem
Existing data-oblivious techniques, such as secret indexing, are inefficient for copying a subarray from one array to another as they do not allow for efficient and data-oblivious operations with respect to the length of the subarray, limiting their application in secure data processing and multi-party computations.
Innovation Solution
A data retrieval device and method that selects different indices for each element in the second array based on the first array's indices, allowing for data-oblivious copying of a subarray by performing linear scans and using cryptographic verifiable computations to ensure the process is secure and efficient, even when the starting and ending indices of the subarray are private values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If secret indexing is used to retrieve elements from an array, then data-oblivious access is achieved, but the technique only allows retrieving a single element and cannot efficiently copy subarrays
Solution Approach 1:
The patent divides the array copying operation into multiple element-level operations. Instead of attempting to copy the entire subarray at once, it processes elements individually using data-oblivious element computation, which can then be composed to achieve efficient subarray copying. This segmentation allows the technique to handle subarray operations while maintaining data-obliviousness.
Solution Approach 2:
The patent introduces a new dimension to the data-oblivious computation by using a counter variable that tracks the current element being processed. This counter dimension enables the system to efficiently manage the copying process across multiple elements without compromising the data-oblivious property, thereby improving productivity while maintaining security.
2Productivity
If different second indices are selected for first indices that differ by less than the length of the subarray, then data-oblivious computation efficiency is improved, but the complexity of index selection increases
Solution Approach 1:
The index selection mechanism is designed to automatically adapt to the input data characteristics. By using a counter variable that naturally increments with each element processed, the system self-regulates the index selection without requiring external intervention or complex control logic. This self-service approach simplifies the overall system while achieving the desired computational efficiency.
Data Source
AI summary
Some embodiments are directed to a data retrieval device 210 for data-obliviously copying a subarray of a first array to a second array. The length of the second array is more than one and less than the length of the first array. The length of the subarray is at most the length of the second array. For each first element at a first index in the first array, the data retrieval device selects a second index in the second array for the first index in the first array; data-obliviously computes a choice bit indicative of whether to copy the first element to the second index in the second array; and replaces a second element at the second index in the second array by a replacement element, the replacement element being data-obliviously set to the first element or the second element based on the choice bit.