When I was playing around recently I used CRC32, taken once forwards across the input and a second time backwards across it. This certainly increased the effective space of the hash -- my sums is not up to any assertion about whether that gives a full 64 bits of "entropy".

There are also two other respectable 32 bit CRCs -- avoiding the need to reverse the input.

There is also CRC64 itself, but a quick poke at CPAN doesn't reveal an implementation (except buried in some "Bio..." stuff). Wouldn't be too difficult to bang out a table driven CRC64.

You don't want anything crypto-secure, so a CRC could well be sufficient, and a good implementation will run like stink compared to any of the crypto-digest stuff.

In reply to Re^3: 64-bit digest algorithms by gone2015
in thread 64-bit digest algorithms by BrowserUk

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