[Nanog] Crypto export restricted prefix list

Is there a prefix list available listing the IP space of cryptographic
export restricted countries? My google skills are failing me. I'm
required to apply a ban on North Korea, Iran, Syria, Sudan and Cuba.

Thanks for the reply. I'm aware of the limitations of this approach.
For the same reasons you stated (proxy etc), I don't expect this to be
foolproof or accurate. I'm only intending to satisfy a demand to "do
something". We already dictate export requirements in the EULA, but
we need to also attempt to block the embargoed countries.

For the archives, my google skills returned and I found this:
http://www.countryipblocks.net/