This research considers the offloading of the IPsec packet encryption algorithm into an FPGA by proposing a hardware acceleration of the AES cryptographic algorithm for IPsec. We point out the benefits of relying on HW acceleration in terms of speed and energy efficiency for applications like IPsec. We present the description of the architecture of the proposed solution, the simulation results of our implementation of the AES algorithm in ECB (Electronic Code Book) mode. We also present the integration of the encryption core with the IPsec subsystem through a PCIe bus interface so that the resulting implementation is interoperable with other systems.