  Semi-quantum key distribution is traditionally based on two-level quantum
systems. In this paper, an unconditional security of a semi quantum key
distribution protocol based on higher-dimensional systems using various
mutually unbiased bases is presented. We first consider the three dimensional
case using three and four mutually unbiased bases and derive a lower bound for
the key rate as a function of the quantum channel's noise. We then generalize
the result to a semi-quantum key distribution protocol that employs different
number of mutually unbiased bases for four-dimensional states. It is found that
basing the semi-quantum key distribution protocol on higher-dimensional
mutually unbiased bases can increase the tolerable threshold of the noise and
the maximum achievable value of the secret key rate.
