This repository provides the source code of Aloha-HE, a hardware accelerator for client-side operations in homomorphic encryption. Aloha-HE targets the CKKS scheme and supports all operations required during encode+encrypt and decode+decrypt in hardware. We publish the source code for the Xilinx ZYNQ-7000 and Kintex-7 FPGA platforms.

The according paper "Aloha-HE: A Low-Area Hardware Accelerator for Client-Side Operations in Homomorphic Encryption" with a detailed explanation of Aloha-HE is available as pre-print and has been accepted for the DATE'24 conference.

All content of this repo is for academic research use only. It does not come with any support, warranty, or responsibility.

We implemented Aloha-HE using Vivado 2019.1. This repo provides these implementations for ZYNQ-7000 (PYNQ-z2 board) and Kintex-7 (Genesys2 board) in their respective directories. In addition to that, users can select between stored FFT twiddle factors and on-the-fly generated FFT twiddle factors. Optional testing functionality allows to read and write all BRAMs in the FPGA. These settings are configured using flags in Aloha-HE_Common/ComputeCore.v. We provide synthesis and implementation results for each of the possible feature combinations. The following tags refer to the corresponding commits:

The folders Aloha-HE_Kintex and Aloha-HE_ZYNQ contain the ready-to-use Vivado 2019.1 and the SDK projects for the Kintex-7 and the ZYNQ-7000 FPGA respectively. The folder Aloha-HE_Common contains the (System-)Verilog files for Aloha-HE. The folder Scripts provides Python scripts to generate primes and constants as well as to set up ROM contents. The ROM contents are defined in .coe files stored in Aloha-HE_Common/MemoryInitializationFiles/.

We provide ready-to-use implementations of Aloha-HE for the PYNQ-z2 and the Genesys2 boards. Follow these steps to run Aloha-HE using Vivado 2019.1 and its SDK environment.

1. Plug in the board and connect the serial port via a terminal. Corresponding scripts for Ubuntu are in the Scripts folder. Use e.g. Putty for Windows.
2. Check out the desired configuration according to the table above. Use git checkout <tag name>.
3. Open the respective Aloha-HE project for the targeted board. The bitstream file may be displayed as out-of-date. This is due to different timestamps caused by git. Just using the provided bitstream is fine, but you can re-run the implementation if you want to.
4. Open the SDK: Go to File -> Launch SDK and click OK.
5. The main testing software is located in ckksTest.c. Uncomment the defines according to the tests you want to run. Productive code (i.e. the code configuration with the best performance and no intermediate checks) is activated by uncommenting FAST_ENCRYPTION and FAST_DECRYPTION.
6. Make sure the software is compiled by saving all files.
7. For ZYNQ-7000 (PYNQ-z2 board): Click Run -> Run Configurations... Then double-click on "GDB Debugger on Local" in the opened window. For Kintex-7 (Genesys 2 board): Click on Xilinx -> Program FPGA -> Program. This flashes the FPGA and the software.
8. We finally are able to execute the just flashed software. For ZYNQ-7000, right-click on the "Aloha-HE" application folder, select Run As..., and click on "Launch on Hardware (System Debugger)". For Kintex-7, right-click on the "Aloha-HE" application folder, select Run As..., and click on "Launch on Hardware (GDB)". This starts software execution and the board will return the results via the serial port.

Florian Krieger - florian.krieger (at) iaik.tugraz.at

Florian Hirner - florian.hirner (at) iaik.tugraz.at

Ahmet Can Mert - ahmet.mert (at) iaik.tugraz.at

Sujoy Sinha Roy - sujoy.sinharoy (at) iaik.tugraz.at

Institute of Applied Information Processing and Communications, Graz University of Technology, Austria

If you use Aloha-HE in your research/study, please cite our work:

@misc{cryptoeprint:2023/1736,
      author = {Florian Krieger and Florian Hirner and Ahmet Can Mert and Sujoy Sinha Roy},
      title = {Aloha-HE: A Low-Area Hardware Accelerator for Client-Side Operations in Homomorphic Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2023/1736},
      year = {2023},
      note = {\url{https://eprint.iacr.org/2023/1736}},
      url = {https://eprint.iacr.org/2023/1736}
}