A method for key agreement between a first party and a second party over a public communications channel, the method including selecting, by the first party, from a semigroup, a first value “a”; multiplying the first value “a” by a second value “b” to create a third value “d”, the second value “b” being selected from the semigroup; sending the third value “d” to the second party; receiving, from the second party, a fourth value “e”, the fourth value comprising the second value “b” multiplied by a fifth value “c” selected by the second party from the semigroup; and creating a shared secret by multiplying the first value “a” with the fourth value “e”, wherein the shared secret matches the third value “d” multiplied by the fifth value “c”.