Secure Odds Ratio Computation Apparatus with Zero-Division Detection
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Solution Overview
Problem
Existing methods for securely calculating the odds ratio in medical statistics face challenges such as overflow in fixed-point arithmetic and undetectable division by zero, which are not addressed in previous secure computation techniques.
Innovation Solution
A computation apparatus and method that uses secure computation to detect division by zero and avoid overflow by employing a division unit, multiplication unit, equality judgment unit, logical operation unit, and selection unit to handle ciphertexts of plaintext values, ensuring the odds ratio is calculated correctly and securely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If secure computation is performed using fixed-point arithmetic to calculate the odds ratio, then computation efficiency is improved compared to logistic regression, but overflow occurs when input values are large
Solution Approach 1:
The patent applies preliminary action by detecting potential overflow conditions before they occur during secure computation. The system checks whether intermediate computation results will exceed the maximum representable value in fixed-point arithmetic, and if so, switches to alternative computation methods or scales the data accordingly, preventing overflow before it compromises computation reliability
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the precision and scale parameters of fixed-point arithmetic based on the magnitude of input values. When large input values are detected, the system modifies the fixed-point parameters to accommodate the larger range, thereby maintaining both computation efficiency and preventing overflow
2Productivity
If secure computation is performed directly on the odds ratio expression, then computation speed is improved, but division by zero cannot be detected and distinguished from normal results
Solution Approach 1:
The patent applies preliminary action by performing zero-checking operations on the denominator values (b and c) before executing the division operations in the odds ratio calculation. This preliminary detection allows the system to identify division by zero conditions in advance, distinguish them from valid computation results, and handle them appropriately without compromising the security or speed of the main computation
Solution Approach 2:
The patent introduces intermediary variables and comparison operations that act as mediators between the secure computation process and error detection. These intermediaries enable the system to detect division by zero conditions while maintaining the encrypted nature of the data, allowing error distinction without revealing underlying values
3Reliability
If logistic regression analysis is performed to calculate the odds ratio securely, then security is maintained, but computational cost increases significantly
Solution Approach 1:
The patent extracts and directly computes only the essential odds ratio formula (ad/bc) from the more complex logistic regression framework. By taking out only the necessary computation components needed for the odds ratio calculation and eliminating unnecessary logistic regression steps, the system maintains security through secure computation protocols while significantly reducing computational cost
Data Source
AI summary
A computation apparatus, a method of the same, and a program which perform a secure computation using fixed-point arithmetic, and overflow is unlikely to occur and the occurrence of division by zero can be detected when an odds ratio is calculated. The computation apparatus includes an odds ratio computation unit for obtaining an odds ratio between a first group (a+b) and a second group (c+d) based on four plaintext values a, b, c, and d, by means of secure computation; a zero-division detection unit for determining, by means of secure computation, whether or not at least one of the plaintext values b and c is not zero, and detecting division by zero; and a selection unit for selecting the odds ratio if division by zero is not detected, by means of secure computation.