Author Topic: Two files with same SHA1 hash  (Read 3185 times)

Offline VG8020

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Two files with same SHA1 hash
« on: April 27, 2011, 08:56:37 AM »
Hello,

To make the story short, TOSEC MSX:

Knockout (1985)(Alligata Software)[RUN'CAS-'].cas
already belongs to the collection

I've made a conversion of the same videogame published by a different company, DISCOVERY Informatic
Knockout! (1986)(DISCOVERY Informatic)(ES)[RUN'CAS-'].cas

Both have the same SHA1 and _most_ probably
Knockout (1985)(Alligata Software)[RUN'CAS-'].cas

is wrongly named - publisher is most likely to be DISCOVERY. However, since there is a remote chance
Knockout (1985)(Alligata Software)[RUN'CAS-'].cas

actually comes from the Alligata tape, how could we go about it?

Since TOSEC is file-hash based, I've thought about naming both companies in the publisher field, eg.
Knockout! (1986)(Alligata Software - DISCOVERY Informatic)(ES)[RUN'CAS-'].cas

But to be more precise, maybe the best thing to do would renaming it to
Knockout! (1986)(DISCOVERY Informatic)(ES)[RUN'CAS-'].cas

Since it's a Discovery release for sure and whenever an Alligata conversion is confirmed, only then add it to TOSEC.

Greetings,



(previously known as MSXfreak)

Offline PandMonium

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Re: Two files with same SHA1 hash
« Reply #1 on: April 27, 2011, 11:55:08 AM »
Don't know if i understood correctly but after all you don't have 2 distinct files, just two exact copies of the same one, right? Hence the exact same SHA1 hash (or it could be an 'impossible' collision but you can test both :P http://www.fileformat.info/tool/hash.htm )

So, the exact same software can be found in two different tapes, one by "Discovery Informatic" and other by "Alligata Software" (released in Spain). Am i right?
In that case, if the file is the same there is no reason to have it duplicated around dats with a different name - they are all the *same*. Not sure how to rename it, most certainly using the original dev/publisher name.
Lets just wait for others' opinion...

Offline TKaos

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Re: Two files with same SHA1 hash
« Reply #2 on: April 27, 2011, 03:08:04 PM »
In those cases I usually went for the publisher that published it first, as the others are just 1:1 copies of the first published software, if you later find a different tape from Alligata Software then of course use them as publisher.

Offline Cassiel

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Re: Two files with same SHA1 hash
« Reply #3 on: April 27, 2011, 08:07:18 PM »
Seconded....

(errr... I mean 'thirded')    :D

Offline VG8020

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Re: Two files with same SHA1 hash
« Reply #4 on: April 28, 2011, 01:30:28 PM »
Hello,

So, the exact same software can be found in two different tapes, one by "Discovery Informatic" and other by "Alligata Software" (released in Spain). Am i right?

That's right. But as long as the file already catalogued in Tosec actually comes from Alligata. I have sound reason to think it does not come from Alligata but from Discovery. How? The TOSEC file supposedly by Alligata was actually converted by a well-known Spanish MSXer; in Spain it was only Discovery who distributed the videogame; my conversion from Discovery has the same SHA1 as the TOSEC file and as the file by the Spanish MSXer... All things considered I'm certain those two files come from the Discovery release. The key to the whole issue is that the TOSEC file should have actually been named Discovery in the publisher field. But, alas, not even Generation-MSX database had knowledge of the Spanish release by Discovery.

In that case, if the file is the same there is no reason to have it duplicated around dats with a different name - they are all the *same*. Not sure how to rename it, most certainly using the original dev/publisher name.
Lets just wait for others' opinion...

I agree. I'm not into duplicating files with same hashes, that'd be way too redundant. Needless.

In those cases I usually went for the publisher that published it first, as the others are just 1:1 copies of the first published software, if you later find a different tape from Alligata Software then of course use them as publisher.

Right, TKaos. I agree with that view too.

Also I would have to have an original Alligata tape, make the conversion and compare it to my Discovery tape and see whether both are 1:1 or there's some sort of difference eg. welcome screen. So far, the only thing we're 100% sure is that my file is a Discovery release.

Thanks for your comments.

Greetings,

(previously known as MSXfreak)