Hardware Acceleration of a Software-based VPN

A Virtual Private Network (VPN) encrypts and decrypts the private traffic it tunnels over a public network. Maximizing the available bandwidth is an important requirement for network applications, but the cryptographic operations add significant computational load to VPN applications, limiting the network throughput. This work presents a coprocessor designed to offer hardware acceleration for these encryption and decryption operations. The open-source SigmaVPN application is used as the base solution, and a coprocessor is designed for the parts of Networking and Cryptography library (NaCl) which underlies the cryptographic operation of SigmaVPN. The hardware-software codesign of this work is implemented on a Xilinx Zynq-7000 SoC, showing a 93% reduction in the execution time of encrypting a 1024-byte frame, and this improved the TCP and UDP communication bandwidths by a factor of 4.36 and 5.36 respectively compared to pure software solution for a 1024-byte frame.