What is the fastest hash algorithm to check if two files are equal?

Question

What is the fastest way to create a hash function which will be used to check if two files are equal?

Security is not very important.

Edit: I am sending a fi

Answer 1

I remember the old modem transfer protocols, like Zmodem, would do some sort of CRC compare for each block as it was sent. CRC32, if I remember ancient history well enough. I'm not suggesting you make your own transfer protocol, unless that's exactly what you're doing, but you could maybe have it spot check a block of the file periodically, or maybe doing hashes of each 8k block would be simple enough for the processors to handle. Haven't tried it, myself.