First crack at imperative HMAC in Cryptol
First crack at imperative HMAC in Cryptol

This version type checks and runs but isn't quite correct yet. Nathan is
going to take over from here.

awslabs/s2n,jldodds/s2n,awslabs/s2n,colmmacc/s2n,wcs1only/s2n,alexeblee/s2n,PKRoma/s2n,PKRoma/s2n,PKRoma/s2n,PKRoma/s2n,PKRoma/s2n,wcs1only/s2n,raycoll/s2n,gibson-compsci/s2n,PKRoma/s2n,awslabs/s2n,alexeblee/s2n,jldodds/s2n,gibson-compsci/s2n,jldodds/s2n,raycoll/s2n,colmmacc/s2n,colmmacc/s2n,wcs1only/s2n,awslabs/s2n,wcs1only/s2n,colmmacc/s2n,raycoll/s2n,wcs1only/s2n,alexeblee/s2n,bpdavidson/s2n,gibson-compsci/s2n,colmmacc/s2n,wcs1only/s2n,wcs1only/s2n,gibson-compsci/s2n,bpdavidson/s2n,raycoll/s2n,alexeblee/s2n,jldodds/s2n,bpdavidson/s2n,bpdavidson/s2n,wcs1only/s2n,bpdavidson/s2n,colmmacc/s2n,PKRoma/s2n,gibson-compsci/s2n,alexeblee/s2n,raycoll/s2n,PKRoma/s2n,jldodds/s2n,awslabs/s2n,awslabs/s2n,alexeblee/s2n,raycoll/s2n,gibson-compsci/s2n,bpdavidson/s2n