don't calculate sha sums for the certificates over and over
don't calculate sha sums for the certificates over and over

we can use cksum to calculate simple checksum much faster than
with using openssl, so we can compute sums only once

jvehent/cipherscan,PeterMosmans/cipherscan,jvehent/cipherscan,MikeDawg/cipherscan,jvehent/cipherscan,MikeDawg/cipherscan,PeterMosmans/cipherscan,MikeDawg/cipherscan,PeterMosmans/cipherscan