[Cryptography] sha1sum speed

[Henry Baker]

At 02:54 PM 4/30/2016, Mark Steward wrote:
>Tell me you cached the files first.
>
>Mark
>
>On Sat, Apr 30, 2016 at 5:00 PM, Henry Baker <hbaker1 at pipeline.com> wrote:
>I just run Linux's 'sha1sum' on a number of very large files, and the calculation took significantly longer than I expected.
>
>'sha1sum' is only modestly faster on a very large file than copying the file.

cached ??

I did say I compared sha1sum with *copying* the file, not just *reading* the file.

Perhaps blast writing a file on some types of storage/filesystems is faster than reading it, but on my machines, writing tends to be somewhat slower than reading, and isn't as overlapped as one might have wished (at least in Linux), so copying tends to be slower than simply reading a file.

I was hoping that some versions of crypto hashing could be done at more-or-less file reading ("line" ?) speed.