|The Secure Wavelet Transform
|Pande, A., and J. Zambreno
|Springer Journal of Real-Time Image Processing (RTIP)
There has been an increasing concern for the security of multimedia transactions over real-time embedded systems. Partial and selective encryption schemes have been proposed in the research literature, but these schemes signiﬁcantly increase the computation cost leading to tradeoffs in system latency, throughput, hardware requirements and power usage. In this paper, we propose a lightweight multimedia encryption strategy based on a modiﬁed discrete wavelet transform (DWT) which we refer to as the secure wavelet transform (SWT). The SWT provides joint multimedia encryption and compression by two modiﬁcations over the traditional DWT implementations: (a) parameterized construction of the DWT and (b) subband re-orientation for the wavelet decomposition. The SWT has rational coefﬁcients which allow us to build a high throughput hardware implementation on ﬁxed point arithmetic. We obtain a zero-overhead implementation on custom hardware. Furthermore, a Look-up table based reconﬁgurable implementation allows us to allocate the encryption key to the hardware at run-time. Direct implementation on Xilinx Virtex FPGA gave a clock frequency of 60 MHz while a reconﬁgurable multiplier based design gave a improved clock frequency of 114 MHz. The pipelined implementation of the SWT achieved a clock frequency of 240 MHz on a Xilinx Virtex-4 FPGA and met the timing constraint of 500 MHz on a standard cell realization using 45 nm CMOS technology.