Energy-Aware Key Exchange for Securing Implantable Medical Devices

Table 1

Average entropy.

#lowest bits	Entropy	# lowest bits	Entropy
H(8IPI)	6.51	H(7IPI′)	5.55
H(7IPI)	6.23	H(6IPI′)	5.26
H(6IPI)	5.87	H(5IPI′)	4.73
H(5IPI)	4.95	H(4IPI′)	3.96
H(4IPI)	3.99	H(3IPI′)	2.99

We let denote the lowest bits other than the least significant bit. In other words, if a least significant bit is removed from the th IPI, then this becomes .