A Lightweight AES Coprocessor Based on RISC-V Custom Instructions

Table 4

Comparison of AES circuits with different implementation routes.

	[27]	[32]	[23]	Proposed
				AES core	Coprocessor
Technology	28 nm	65 nm	65 nm	65 nm
Voltage (V)	0.5	1.1	0.8	1.2
Frequency (MHz)	50	100	16	100
Cycles (block)	213	527	11	12^c	11 27
Area (mm^2)	0.002 8	0.005 4	0.015	0.014 7	0.031 6(2.150 )
Power (mW)	0.045	0.246	—	6.07^c	7.19^c (1.184 )
Energy efficiency (pJ bit^−1)	1.5^a	10.13	4.08^b
(norm to 1.2 V)	(4.31)	(12.05)	(9.18)	5.69	—

^aData at TSMC-28-nm technology. ^bMeasured energy. ^cData obtained by encrypting 16 blocks of plaintext in CBC mode.