Breaking Secure Aggregation: Label Leakage from Aggregated Gradients in Federated Learning

Fuente: arXiv
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Hauptverfasser: Wang, Zhibo, Chang, Zhiwei, Hu, Jiahui, Pang, Xiaoyi, Du, Jiacheng, Chen, Yongle, Ren, Kui
Format: Preprint
Veröffentlicht: 2024
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author Wang, Zhibo
Chang, Zhiwei
Hu, Jiahui
Pang, Xiaoyi
Du, Jiacheng
Chen, Yongle
Ren, Kui
author_facet Wang, Zhibo
Chang, Zhiwei
Hu, Jiahui
Pang, Xiaoyi
Du, Jiacheng
Chen, Yongle
Ren, Kui
contents Federated Learning (FL) exhibits privacy vulnerabilities under gradient inversion attacks (GIAs), which can extract private information from individual gradients. To enhance privacy, FL incorporates Secure Aggregation (SA) to prevent the server from obtaining individual gradients, thus effectively resisting GIAs. In this paper, we propose a stealthy label inference attack to bypass SA and recover individual clients' private labels. Specifically, we conduct a theoretical analysis of label inference from the aggregated gradients that are exclusively obtained after implementing SA. The analysis results reveal that the inputs (embeddings) and outputs (logits) of the final fully connected layer (FCL) contribute to gradient disaggregation and label restoration. To preset the embeddings and logits of FCL, we craft a fishing model by solely modifying the parameters of a single batch normalization (BN) layer in the original model. Distributing client-specific fishing models, the server can derive the individual gradients regarding the bias of FCL by resolving a linear system with expected embeddings and the aggregated gradients as coefficients. Then the labels of each client can be precisely computed based on preset logits and gradients of FCL's bias. Extensive experiments show that our attack achieves large-scale label recovery with 100\% accuracy on various datasets and model architectures.
format Preprint
id arxiv_https___arxiv_org_abs_2406_15731
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Breaking Secure Aggregation: Label Leakage from Aggregated Gradients in Federated Learning
Wang, Zhibo
Chang, Zhiwei
Hu, Jiahui
Pang, Xiaoyi
Du, Jiacheng
Chen, Yongle
Ren, Kui
Cryptography and Security
Artificial Intelligence
Federated Learning (FL) exhibits privacy vulnerabilities under gradient inversion attacks (GIAs), which can extract private information from individual gradients. To enhance privacy, FL incorporates Secure Aggregation (SA) to prevent the server from obtaining individual gradients, thus effectively resisting GIAs. In this paper, we propose a stealthy label inference attack to bypass SA and recover individual clients' private labels. Specifically, we conduct a theoretical analysis of label inference from the aggregated gradients that are exclusively obtained after implementing SA. The analysis results reveal that the inputs (embeddings) and outputs (logits) of the final fully connected layer (FCL) contribute to gradient disaggregation and label restoration. To preset the embeddings and logits of FCL, we craft a fishing model by solely modifying the parameters of a single batch normalization (BN) layer in the original model. Distributing client-specific fishing models, the server can derive the individual gradients regarding the bias of FCL by resolving a linear system with expected embeddings and the aggregated gradients as coefficients. Then the labels of each client can be precisely computed based on preset logits and gradients of FCL's bias. Extensive experiments show that our attack achieves large-scale label recovery with 100\% accuracy on various datasets and model architectures.
title Breaking Secure Aggregation: Label Leakage from Aggregated Gradients in Federated Learning
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2406.15731