Somewhat Homomorphic Encryption (SHE) schemes allow to carry out operations on data in the cipher domain. In a cloud computing scenario, personal information can be processed secretly, inferring a high level of confidentiality. For many years, practical parameters of SHE schemes were overestimated, leading to only consider the FFT algorithm to accelerate SHE in hardware. Nevertheless, recent work demonstrates that parameters can be lowered without compromising the security [1]. Following this trend, this work investigates the benefits of using Karatsuba algorithm instead of FFT for the Fan-Vercauteren (FV) Homomorphic Encryption scheme. The proposed accelerator relies on an hardware/software co-design approach, and is designed to perform fast arithmetic operations on degree 2560 polynomials with 135 bits coefficients, allowing to compute small algorithms homomorphically. Compared to a functionally equivalent design using FFT, our accelerator performs an homomorphic multiplication in 11.9 ms instead of 15.46 ms, and halves the size of logic utilization and registers on the FPGA.

International audienceSomewhat Homomorphic Encryption (SHE) schemes can be used to carry out operations on ciphered data. In a cloud computing scenario, personal information can be processed secretly, inferring a high level of confidentiality. The principle limitation of SHE is the size of ciphertext compared to the size of the message. This issue can be addressed by using a batching technique that "packs" several messages into one ciphertext. However, this method leads to important drawbacks in standard implementations. This paper presents a fast hardware/software co-design implementation of an encryption procedure using the Karatsuba algorithm. Our hard- ware accelerator is 1.5 times faster than the state of the art for 1 encryption and 4 times faster for 4 encryptions

Many-core architectures are becoming a major execution platform in order to face the increasing number of applications executed in parallel. While many-core accelerator architectures offer users with massive parallelism and high performance, it also introduces some key challenges in terms of security. Indeed, in order to leverage performance, a great number of applications running in parallel may share resources. A malicious application may compromise other applications sharing resources with or the whole system by directly accessing, deducing or retrieving sensitive data. This work focuses on a many-core accelerator architecture extended with mechanisms allowing the logical and spatial isolation of sensitive applications through the dynamic creation of secure zones. Each sensitive application is executed within a secure zone avoiding any resource sharing with other potentially malicious applications, preventing denial of services within the secure zones as well as confidentiality and integrity attacks. A set of services guarantying the dynamic creation and handling of spatially isolated secure zones in a many-core accelerator architecture are proposed. These services are integrated into a software controller on a many-core accelerator architecture and evaluated through virtual prototyping.