Re: Which hashing algorithm is best to check file duplicity?
| From: | Paul M Foster | Date: | Sun, 15 Mar 2009 21:40:35 +0000 |
| Subject: | Re: Which hashing algorithm is best to check file duplicity? | ||
| References: | 1 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-290101@lists.php.net to get a copy of this message | ||
On Sun, Mar 15, 2009 at 10:25:11PM +0100, Martin Zvarík wrote:
> I want to store the file's hash to the database, so I can check next
> time to see if that file was already uploaded (even if it was renamed).
>
> What would be the best (= fastest + small chance of collision) algorithm
> in this case?
>
> Is crc32 a good choice?
>
> Thank you in advance,
> Martin
According to wikipedia, a CRC is not sufficient to detect intentional
alteration of a file/message, since it's relatively easy to design a
message/file which will have the same CRC. On the other hand, CRC, by
design will reliably detect subtle changes to a message/file.
Paul
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Paul M. Foster