Secure Computation Window Function via Flag Columns
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Solution Overview
Problem
There is no reported method for realizing the window function on secure computation, which requires grouping by key attributes and totaling within a window frame while keeping the data encrypted.
Innovation Solution
A secure computation apparatus that generates flag columns to identify the window frame boundaries, performs share conversion, and executes product-sum operations on encrypted data to compute the Sum operation of the window function using low-cost arithmetic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secure computation is used to keep data encrypted during window function computation, then data confidentiality is maintained, but computational complexity and cost increase
Solution Approach 1:
The patent segments the window frame identification into multiple flag columns (former half window frame flag column and latter half window frame flag column) to simplify the secure computation process. By dividing the complex window frame boundary detection into smaller, manageable segments, the computational complexity is reduced while maintaining data confidentiality through encrypted operations.
Solution Approach 2:
The patent introduces flag columns as intermediary elements that facilitate window frame identification without requiring direct decryption of the data. These flag columns act as mediators that encode window frame boundary information in an encrypted manner, enabling the secure computation system to perform window function operations while maintaining data confidentiality.
2Reliability
If traditional secure computation methods are used for window functions, then data remains encrypted, but arithmetic operation costs increase
Solution Approach 1:
The patent changes the representation parameters of window frame information by using flag columns with specific binary patterns (0 and 1 values) to indicate window frame boundaries. This parameter transformation allows the secure computation system to perform arithmetic operations more efficiently, as the flag columns enable simpler encrypted comparisons and selections, thereby reducing arithmetic operation costs while maintaining data encryption.
3Reliability
If window function computation is performed on encrypted data, then data confidentiality is preserved, but computation efficiency decreases
Solution Approach 1:
The patent performs preliminary actions by pre-computing and storing flag columns that encode window frame boundary information before the actual window function computation. This preliminary preparation of structured encrypted markers enables faster subsequent computations, as the system can efficiently identify and process window frames using the pre-prepared flag columns rather than performing complex boundary detection during the computation phase.
Data Source
AI summary
A secure computation apparatus includes a former half window frame column generation unit configured to generate, with respect to subVector ({g→}, s+1, i}, a bit column obtained by an OR operation performed on all bits from the end to each position as {wf→}, a latter half window frame column generation unit configured to generate, with respect to subVector ({g→}, i+1, t}, a bit column obtained by an OR operation performed on all bits from the head to each position as {wl→}, a window frame flag column generation unit configured to generate {w→} by combining {wf→} and {wl→}, an inverted window frame flag column generation unit configured to generate {w′→} by performing a NOT operation on {w→}, a share conversion unit configured to convert {w′→} into [[w′→]], and a product-sum operation unit configured to execute a product-sum operation on subVector ([[v′→]], s, t) and [[w′→]].