Kahan's surname is of Jewish origin.
Kahan is the surname of occupational origin, and refers to a priest, and derived from the Hebrew Kohen.
In Jewish tradition the priests have a hereditary caste are supposed to be descendants of Aaron the brother of Moses.
Not all who bear the name Kahan belong to the priestly caste at present, because during the war periods had to engage in other activities lost in different lines of lineage tradition.