Comparison Criteria - MD5 or SHA

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philibertperusse

Comparison Criteria - MD5 or SHA

Post by philibertperusse »

The comparison criteria for copying files lists CRC32 as a way to compare files for CONTENT only. However, CRC32 is not a very very good hashing/comparison. There are too many true negatives possible (as opposed to a false positive), meaning that file may have changed but changes are not detected.

A MD5 hash or SHA hash calculation would provide a better technique for comparing files on CONTENT only.

By the way, I find Backup4all very easy to use. The UI is simple, straight forward, clean. I am doing backup software evaluation and this is definitely the software I would rather use. When it comes down to features it is also quite impressive. There are only a few things in terms of features that makes me question this choice and makes me lean toward "Uranium Backup", though Uranium UI and setup is awful the features/behavior/options is just a bit more appropriate for my needs.

Adrian (Softland)
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Joined: Wed Dec 16, 2009 12:46 pm
Location: Cluj-Napoca, Romania
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Re: Comparison Criteria - MD5 or SHA

Post by Adrian (Softland) »

Hi,

We do not have any plans to change from CRC32 to MD5.
MD5 is frequently used for data security.
We consider that CRC32 is very good as long as you cannot modify a file and have the same CRC.

dbailey75
Posts: 1
Joined: Mon Jun 24, 2013 12:46 pm

Re: Comparison Criteria - MD5 or SHA

Post by dbailey75 »

[quote="Support"]Hi,

We do not have any plans to change from CRC32 to MD5.
MD5 is frequently used for data security.
We consider that CRC32 is very good as long as you cannot modify a file and have the same CRC.[/quote]

I would like to be able to export a backup file list with the crc32 hash, or even see a list of all changed files before backing up, I can use the information to help prevent bit rot over time with all my personal digital files when running the data verification test.

appreciate the good work,

Thanks.

Adrian (Softland)
Posts: 1590
Joined: Wed Dec 16, 2009 12:46 pm
Location: Cluj-Napoca, Romania
Contact:

Re: Comparison Criteria - MD5 or SHA

Post by Adrian (Softland) »

Hi,

You cannot export a list of the modified files, but you can see them in Backup4all.
Please follow these steps:
1. Open Backup4all
2. Go to Explore View (F2)
3. Above the Explore window you have 5 buttons to show/hide different files (new, unchanged, modified etc)
Press Ctrl+3 to show/hide modified files.

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