I'm sure someone will multiply anything by n but that doesn't mean their code is right. I can't think of any legitimate use for thousands of incomplete hashes without so much other memory the hash is dwarfed. Can you?

The argument about streamlined vpn or ssl devices is not relevant here: such a device has to calculate hashes, but it doesn't have to keep hash states open. Hash a message, make/check the signature, forward or discard, O(k) memory use where k is the number of cores.

I agree that a per connection overhead of this size for every TCP connection is a terrible thing, but I think marshray forgot we were talking about places where you use hashes, and keep them open.