
358 Communication Architectures for SoC
signals with a masking-bit, then later removes the mask by doing another XOR
operation. In this approach, each probably attacked signal b is represented by
b
m
= b ⊕ m
b
,wherem
b
is a uniformly distributed random variable (i.e.,
p(mb =0)=p(mb =1)=1/2) and is independent of b. Consequently, the
b
m
also is a uniformly distributed random variable. In the masking-approach,
a circuit is replaced with a masked implementation. For example, a 2-input
XOR function g = a ⊕ b is replaced with g
m
= a
m
⊕ b
m
and m
g
= m
a
⊕ m
b
.
Werefertotheimplementationg
m
as M-XOR gate. The m
g
signal is called
its correction mask.
Masking on the gate lev