multi-stage cryptographic computations
It might mean that any multi-stage cryptographic protocols – which require parties to store temporary data – could be weakened by exposure/tampering of this data. To ensure that does not happen, one needs to protect these intermediate chunks of data and (preferrably) the encryption process itself so that we can trust that, if the protocol finished successfully, it's results are to be trusted. 

One of the ways to protect it, is to offload all computations to HSM – which is compartmented from your regular process memory and thus is less likely to be tampered when your server gets compromised.