Two new FPGA designs for the Advanced Encryption Standard (AES) are presented. The first is believed to be the fastest, achieving 25 Gbps throughput using a Xilinx Spartan-III (XC3S2000) device. The second is believed to be the smallest and fits into a Xilinx Spartan-II (XC2S15) device, only requiring two block memories and 124 slices to achieve a throughput of 2.2 Mbps. These designs show the extremes of what is possible and have radically different applications from high performance e-commerce IPsec servers to low power mobile and home applications. The high speed design presented here includes support for continued throughput during key changes for both encryption and decryption which previous pipelined designs have omitted.