Secure Computation Window Frame Flag Column Generation
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Solution Overview
Problem
There is no method reported in literature for realizing the window function on secure computation, as it requires performing grouping according to key attributes and totaling within a window frame while encrypting the grouping and window frame boundaries.
Innovation Solution
A secure computation apparatus that generates a window frame flag column using low-cost arithmetic operations, by employing a group flag column, replicated secret sharing, and bit operations such as OR, PrefixOR, and SuffixOR to create the window frame flag column.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional secure computation methods are used to perform window function, then data security is maintained, but computation cost becomes excessively high
Solution Approach 1:
The window frame flag column generation is segmented into three independent units: former half window frame column generation unit, latter half window frame column generation unit, and window frame flag column generation unit. Each unit processes specific portions of the computation, allowing parallel execution and reducing overall computation cost while maintaining data security through encrypted operations.
Solution Approach 2:
The system performs preliminary actions by pre-generating group flag columns that mark group boundaries before the actual window function computation. These pre-computed flags are then reused during the window frame calculation, avoiding redundant computations and reducing the overall computational burden while keeping data encrypted.
2Loss of information
If encryption is applied to protect database content during window function computation, then data confidentiality is preserved, but the complexity of arithmetic operations increases
Solution Approach 1:
The invention extracts and processes only the necessary components for window frame determination (group flag columns and position indicators) separately from the main data computation. By isolating the frame generation logic into dedicated units that operate on encrypted position data rather than full data values, the arithmetic complexity is reduced while maintaining confidentiality.
Solution Approach 2:
The system introduces encrypted position indicators and group flag columns as intermediary elements that mediate between the encrypted data and the window function logic. These intermediaries allow the system to determine window frames without directly decrypting or comparing full data values, simplifying the arithmetic operations required for frame determination while preserving data confidentiality.
Data Source
AI summary
The secure computation apparatus includes: a former half window frame column generation unit configured to generate, with respect to a vector subVector ({g→}, s+1, i} obtained by extracting elements from an (s+1)-th element to an i-th element of {g→}, a bit column obtained by an OR operation performed on all bits from the end to each position as a former half window frame flag column {wf→}; a latter half window frame column generation unit configured to generate, with respect to a vector subVector ({g→}, i+1, t} obtained by extracting elements from an (i+1)-th element to a t-th element of {g→}, a bit column obtained by calculating OR of all bits from the head to each position as a latter half window frame flag column {wl→}; and a window frame flag column generation unit configured to generate a window frame flag column {w→} by combining the former half window frame flag column {wf→} from the front side and the latter half window frame flag column {wl→} from the rear side having {0} interposed therebetween.