In this question h$$ is a cryptographic hash function that has the following properties:

$1.$ Given h$($x$)$ and y where x and y are integers, it is possible to quickly compute h$($x$$y$)($where $$ denotes multiplication$).$

$2.$ Given h$($x$)$ and h$($y$)$ where x and y are integers, it is impractical to compute h$($x$$y$).$

Assume A and B have been participating in an ongoing non$-$confidential online exchange $($hence not using any form of encryption$).$ Suddenly A tells B that the rest of their online interaction is confidential and should be encrypted using a session key that they must somehow agree on$.$ They do not have a shared secret, and neither of them has a public key, therefore the information they exchange in any protocol they use for agreeing on a session key k$,$ will be visible to adversaries like Eve or Mallory. This question is about the suitability of the following protocol for A and B to agree on a session key k and using it to communicate confidentially.