[Gambas-user] MD5SUM collisions

[Ron_1st]

On Friday 24 October 2008, Kari Laine wrote:
> Hi,
> 
> referring to discussion few days back I have now tested md5sum with 540388
> files and got NO collisions - I think. Method I used was to calculate md5sum
> and sha512sum for all those files.
> then I asked from database distinct total values for both fields and they
> come up with the same number. In my thinking if there would have been
> collisions with md5sum then numbers should have differed.
> Problem is that if md5sum and sha512sum would have collisions with the same
> file - but I think that's quite unlikely - is it?

I can't imagine that will happen, you are right in my opinion.

> 
> I make my backup program to take a file identified by sha512sum and size. I
> am not going to run compare for all the files because that would take a
> month with my machine. Calculating the checksums took about a week because
> there were total 1240333 files. So lot of duplicates which is exactly why I
> want to make the program copy files only once.
> 
> Best Regards
> Kari Laine

Nice to hear the result. So the theory story is now proven by your test.
Did you see a big difference between the used time for md5 and sha methods?

Anyway happy cleaning up your archive and backing up the remaining part.

Best regards
Ron_1st