Checksum What is Verified Checksum [Someone educate me in simple terms]

[Pardzz]

Hi All,

 

PKMN Trainer Pardzz here, I would like to know what "Verify Checksum" is on the SAV tab in PKHeX, my initiative is telling me that is how to check if your save is legal, am I right ???

 

Lots of Love,

Pardzz

[Byewgz]

"A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify data integrity but are not relied upon to verify data authenticity."

[theSLAYER]

Let's say you have a file. A large file. And data can corrupt over time, depending on storage medium.

Now, let's say if you looked at the data a few years later, how would you know whether the data became corrupted?

That is where the checksum comes in. If you think about it simply, without resorting to complicated algorithms, checksums does this:
it checks if the file is corrupt, based on the sum of the data.

Simple checksums calculate every byte in a data file, to get a number. Let's call this calculated checksum.
Then, on the file itself, it has the data of a previously written checksum. Let's call this written checksum.


If the calculated checksum doesn't equal to the written checksum, there's 2 reasons:
1) You used the wrong method to achieve the calculated checksum, or
2) The file is corrupt.

[elmo44]

If the file is corrupted, how to repair it?

[Kaphotics]

2 hours ago, elmo44 said:

If the file is corrupted, how to repair it?

If the checksums are invalid, then all you have to do is export the file from PKHeX and it will apply the correct values. It is important to ponder why the checksums were originally invalid -- did you manually modify the save file? Is the dump actually "complete" and not a glitched dump from dirty cartridge contacts resulting in bad reads? Is it from a ROM Hack which has modified the save structure, resulting in different checksum locations or calculation methods?

[elmo44]

This is a backup file from a GB Crystal cartridge, I exported it by Epilogue Playback software and I edited it.

Edited February 29 by elmo44