Re: SHA-512 in django model? Optimization help?

Hi again!

Something I forgot to mention earlier: If the files are not too big,
consider generating the SHA-512 on the fly instead of storing it.
Space-wise, it is the best possible optimization, obviously. And it
frees you from having to ensure consistency between the file and the hash.


René


On 4/8/19 3:12 AM, Benjamin Schollnick wrote:
> Right now, I'm generating a SHA-512 of a file in my Django model, but
> that requires a string of 128 bytes…
>
> I'm not positive on a better way to store the sha-512 in my model?  Can
> anyone suggest a method / design that would be better optimized?
>
> A quick test, looks like I might be able to store this in a blob of 64
> bytes, which would be a considerable savings…
>
> t = hashlib.sha512(test.encode("utf-16"))
> digest = t.digest()
> len(digest)
> 64
>
> t = hashlib.sha512(test.encode("utf-16"))
> hexdigest = t.hexdigest()
> len(hexdigest)
> 128
>
> But thinking about it, I could convert the hex digest to an integer?
>
> int(hexdigest,16)
> 4298666745768817459166789395753510504053621749752930724783367173454957154660445390018210346619930005782627382250329880502243093184532984814018267510704707
> z = int(hexdigest,16)
> type(z)
> <class 'int'>
>
>
> '52137203c3c4b62bc981fd9c8770952bfd1984ee9ce6e33ec94e485bc31a5631b6c6d15c1a2646f39c887575b576e66ed1ddbd96112d5355e574f06df8878a43'
> 0x52137203c3c4b62bc981fd9c8770952bfd1984ee9ce6e33ec94e485bc31a5631b6c6d15c1a2646f39c887575b576e66ed1ddbd96112d5355e574f06df8878a43
>
> They convert identically, but I'm not sure that converting to integer
> would keep the integrity of the sha-512?
>
> Can anyone make any sort of suggestion on the best way to handle this?
>
> - Benjamin
>
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René Fleschenberg

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Phone: +49 1577 170 7363
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E-mail: rene@fleschenberg.net

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