Lifelong DP: Consistently Bounded Differential Privacy in Lifelong Machine Learning
This addresses privacy protection for data in lifelong learning systems, which is an incremental advancement in differential privacy for sequential tasks.
The paper tackles the problem of unknown privacy risks in lifelong machine learning by introducing Lifelong DP, a formal definition that protects data across all tasks with a consistently bounded privacy budget, and proposes the L2DP-ML algorithm, which shows significant improvements over baselines in evaluations.
In this paper, we show that the process of continually learning new tasks and memorizing previous tasks introduces unknown privacy risks and challenges to bound the privacy loss. Based upon this, we introduce a formal definition of Lifelong DP, in which the participation of any data tuples in the training set of any tasks is protected, under a consistently bounded DP protection, given a growing stream of tasks. A consistently bounded DP means having only one fixed value of the DP privacy budget, regardless of the number of tasks. To preserve Lifelong DP, we propose a scalable and heterogeneous algorithm, called L2DP-ML with a streaming batch training, to efficiently train and continue releasing new versions of an L2M model, given the heterogeneity in terms of data sizes and the training order of tasks, without affecting DP protection of the private training set. An end-to-end theoretical analysis and thorough evaluations show that our mechanism is significantly better than baseline approaches in preserving Lifelong DP. The implementation of L2DP-ML is available at: https://github.com/haiphanNJIT/PrivateDeepLearning.