SecureBoost: A Lossless Federated Learning Framework

TLDR

User privacy protection is a key concern in machine learning, highlighted by the GDPR in the EU, motivating the development of privacy‑preserving data sharing frameworks. The paper proposes SecureBoost, a lossless privacy‑preserving tree‑boosting system for federated learning, and examines ways to reduce information leakage during its execution. SecureBoost performs privacy‑preserving entity alignment, then builds boosting trees across multiple parties with encrypted data, enabling joint learning over vertically partitioned datasets with common user samples. SecureBoost achieves accuracy comparable to non‑privacy‑preserving and centralized gradient tree‑boosting methods while revealing no private data, making it scalable and suitable for industrial applications such as credit risk analysis.

Abstract

The protection of user privacy is an important concern in machine learning, as evidenced by the rolling out of the General Data Protection Regulation (GDPR) in the European Union (EU) in May 2018. The GDPR is designed to give users more control over their personal data, which motivates us to explore machine learning frameworks for data sharing that do not violate user privacy. To meet this goal, in this paper, we propose a novel lossless privacy-preserving tree-boosting system known as SecureBoost in the setting of federated learning. SecureBoost first conducts entity alignment under a privacy-preserving protocol and then constructs boosting trees across multiple parties with a carefully designed encryption strategy. This federated learning system allows the learning process to be jointly conducted over multiple parties with common user samples but different feature sets, which corresponds to a vertically partitioned data set. An advantage of SecureBoost is that it provides the same level of accuracy as the non-privacy-preserving approach while at the same time, reveals no information of each private data provider. We show that the SecureBoost framework is as accurate as other non-federated gradient tree-boosting algorithms that require centralized data and thus it is highly scalable and practical for industrial applications such as credit risk analysis. To this end, we discuss information leakage during the protocol execution and propose ways to provably reduce it.