Dria

Summary

This report details an inefficiency in the sqrt (square root) function of the Solidity-based Statistics library. The sqrt function uses the Babylonian method, an iterative algorithm, which, while accurate, may be less gas-efficient than alternative approaches, especially for large numbers or high-frequency calls. This inefficiency could lead to higher transaction costs and increased execution time.

Vulnerability Details

The sqrt function uses the Babylonian method, which iteratively approximates the square root of a number. This method can be gas-expensive, particularly when called with large numbers or multiple times in a contract execution. Each iteration increases gas consumption, making the function costly if executed frequently or with high input values.

The sqrt function performs iterative calculations until it approximates the square root:

Each loop iteration consumes additional gas, and for larger numbers, this function could iterate many times before reaching convergence, leading to high transaction costs.

Impact

This inefficiency impacts the cost and performance of any contracts relying on frequent or large square root calculations, potentially increasing gas costs significantly. Contracts that involve mathematical operations or high-frequency calculations could face heightened costs, making them less attractive or more costly for users.

Tools Used

Manual review.

Recommendations

1. For specific applications, a single-pass approximation, such as the bitwise method, could be more efficient. This method has a trade-off between precision and gas cost, so it should be used if slight inaccuracies are acceptable.

2. Implement the sqrt function with a fixed maximum iteration count or threshold to reduce gas costs, trading off minor accuracy losses.