[Digikam-users] backup and data integrity

[Jakob Østergaard Hegelund]

On Tuesday 22 January 2008, Arnd Baecker wrote:
> On Mon, 21 Jan 2008, Gerhard Kulzer wrote:
>
> [...]
>
> > Arnd, can you send me the script? I'd like to try too.
>
> Done (off-list, it is really not ment for general consumption ... ;-)
>
> > I just read that strigi is exactly doing what we want, comparing
> > files with sha1. Maybe sha1 is faster than md5?
>
> No idea. Maybe we should do a speed test at some point ;-)

Both sha1 and md5 are designed to make it difficult to create a file 
with a specific checksum.  This is necessary for applications like 
digital signatures, but it usually comes at a significant performance 
(and complexity) premium.

CRCs, on the other hand, were meant to catch what you're trying to 
catch, and will usually be a lot faster.

A CRC64 should be more than sufficient to catch any of the mismatches 
you're looking for (CRC32, such as reported by the cksum command, would 
probably be good enough for most purposes as well). And it will 
definitely be much much faster than the cryptographically secure 
hashes.


-- 
Jakob Østergaard Hegelund