2022/05/28 by Dong, Wei, Liang, Yuting, Yi, Ke · 4 citations
#Cryptography and Security (cs.CR) #Data Structures and Algorithms (cs.DS) #FOS: Computer and information sciences #Machine Learning (cs.LG)
paper · doi:10.48550/arxiv.2205.14324
In this paper, we present two new algorithms for covariance estimation under concentrated differential privacy (zCDP). The first algorithm achieves a Frobenius error of O(d1/4√(tr)/√(n) + √(d)/n), where tr is the trace of the covariance matrix. By taking tr=1, this also implies a worst-case error bound of O(d1/4/√(n)), which improves the standard Gaussian mechanism's O(d/n) for the regime d>\widetildeΩ(n2/3). Our second algorithm offers a tail-sensitive bound that could be much better on skewed data. The corresponding algorithms are also simple and efficient. Experimental results show that they offer significant improvements over prior work.