  We offer a public key exchange protocol based on a semidirect product of two
cyclic (semi)groups of matrices over Z_p. One of the (semi)groups is additive,
the other one multiplicative. This allows us to take advantage of both
operations on matrices to diffuse information. We note that in our protocol, no
power of any matrix or of any element of Z_p is ever exposed, so all standard
attacks on Diffie-Hellman-like protocols (including Shor's quantum algorithm
attack) are not applicable.
