Federated deep learning (FDL) is a promising privacy-preserving approach for training deep neural networks on distributed datasets without raw data sharing. But the classical synchronous FDL faces straggler problem: slow trainers severely impede overall efficiency. Inspired by speculative execution techniques in modern processors, this paper proposes SwiftFL, a novel and efficient speculative training system for FDL. Instead of simply waiting for slower trainer, SwiftFL proactively updates the global model with predicted gradients, enabling faster trainers to speculatively initiate the next training round. Furthermore, a gradient compensation technique is proposed to correct mispredicted training without re-training. Finally, to overcome the model-drift problem caused by fast trainers perform more local training rounds, we propose a client selection strategy. This strategy determines whether trainers should perform speculative training by striking a balance between two metrics: model drift degree and local training efficiency. In the evaluation, we compare SwiftFL with four state-of-the-art FDL systems and demonstrate that SwiftFL achieves an average speedup of 6.08× while maintaining consistent final model accuracy.

Fully Homomorphic Encryption (FHE) enables secure offloading of computations to untrusted cloud servers as it allows computing on encrypted data. However, existing well-known FHE schemes suffer from heavy performance overheads. Thus numerous accelerations based on FPGAs, ASICs, and GPUs have been proposed. Compared to FPGAs and ASICs, GPUs have obvious advantages in productivity and development costs. And also, GPUs have already been widely deployed in commercial cloud or supercomputing centers. Therefore, we present HE-Booster, an efficient GPU-based FHE acceleration design. For single-GPU acceleration, a thorough systematic design is exploited to map five common phases in typical FHE schemes to the GPU parallel architecture. In particular, inspired by the regular architecture of NTT/INTT, a novel inter-thread local synchronization is proposed to exploit thread-level parallelism. For multi-GPU acceleration, we propose a scalable parallelization design that exploitsdata-level parallelismthrough fine-grained data partition under different representations. Finally, experiments on 1 NVIDIA GPU demonstrate that our work outperforms 251.7×, 78.5× and 164.9× than three mainstream CPU-based libraries HElib, SEAL, and PALISADE, and up to 170.5× speedup is obtained compared to the GPU-accelerated library cuHE. What's more, performing 8 homomorphic multiplications on 8 GPUs can deliver up to a 7.66× performance boost compared to a single-GPU implementation.

Federated Learning (FL) is a promising approach to privacy-preserving machine learning. However, recent works reveal that gradients can leak private data. Using trusted SGX-processors for this task yields gradient-preserving but requires to prevent exploitation of any side-channel attacks.

With its huge real-world demands, large-scale confidential computing still cannot be supported by today's Trusted Execution Environment (TEE), due to the lack of scalable and effective protection of high-throughput accelerators like GPUs, FPGAs, and TPUs etc. Although attempts have been made recently to extend the CPU-like enclave to GPUs, these solutions require change to the CPU or GPU chips, may introduce new security risks due to the side-channel leaks in CPU-GPU communication and are still under the resource constraint of today's CPU TEE.To address these problems, we present the first Heterogeneous TEE design that can truly support large-scale compute or data intensive (CDI) computing, without any chip-level change. Our approach, called HETEE, is a device for centralized management of all computing units (e.g., GPUs and other accelerators) of a server rack. It is uniquely designed to work with today's data centres and clouds, leveraging modern resource pooling technologies to dynamically compartmentalize computing tasks, and enforce strong isolation and reduce TCB through hardware support. More specifically, HETEE utilizes the PCIe ExpressFabric to allocate its accelerators to the server node on the same rack for a non-sensitive CDI task, and move them back into a secure enclave in response to the demand for confidential computing. Our design runs a thin TCB stack for security management on a security controller (SC), while leaving a large set of software (e.g., AI runtime, GPU driver, etc.) to the integrated microservers that operate enclaves. An enclaves is physically isolated from others through hardware and verified by the SC at its inception. Its microserver and computing units are restored to a secure state upon termination.We implemented HETEE on a real hardware system, and evaluated it with popular neural network inference and training tasks. Our evaluations show that HETEE can easily support the CDI tasks on the real-world scale and incurred a maximal throughput overhead of 2.17% for inference and 0.95% for training on ResNet152.