[Cryptography] Strict memory hard hash functions

[Sergio Lerner]

Hi!
I've been playing with a property I named Strict memory hard hash
functions.  Strict memory hard functions are an extension of memory hard
functions such that a slight reduction in the memory available for
computation, compared to a predefined optimal memory size, makes the
function evaluation exponentially slower or infeasible. The main
application of strict memory hard functions is to prove a certain amount
of memory is used during a certain time interval or in a certain
computation. This in turn can be used to attest that areas of memory of
devices do not contain hidden data. Other applications are password
hashing and proof of work. I wrote a preliminary paper of  SeqMemoHash
and TreeMemoHash, two strict sequential memory hard functions under the
random oracle model.

It can be downloaded here:
http://bitslog.files.wordpress.com/2013/12/memohash-v0-1.pdf

Please send me comments regarding the security/usefulness of these
constructions!

Best regards and happy new year,
 Sergio.