Systems-on-a-Chip are among the best-performing and complete solutions for complex electronic systems. This is also true in the field of network security, an application requiring high performance with low resource usage. This work presents an Advanced Encryption Standard implementation for Systems-on-a- Chip using as a reference the Cipher Block Chaining mode. In particular, a flexible interface based and the Advanced Peripheral Bus to integrate the encryption algorithm with any kind of processor is presented. The hardware-software approach of the architecture is also analyzed and described. The final system was integrated on a Xilinx Zynq 7000 to prototype and evaluate the idea. Results show that our solution demonstrates good performance and flexibility with low resource usage, occupying less than 2% of the Zynq 7000 with a throughput of 320 Mbps. The architecture is suitable when implementations of symmetric encryption algorithms for modern Systems-on-a-Chip are required.