Comparison Criteria - MD5 or SHA

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philibertperusse

Comparison Criteria - MD5 or SHA

Post by philibertperusse » Thu Sep 30, 2010 11:53 am

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.

Support
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Re: Comparison Criteria - MD5 or SHA

Post by Support » Fri Oct 01, 2010 11:37 am

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
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Joined: Mon Jun 24, 2013 12:46 pm

Re: Comparison Criteria - MD5 or SHA

Post by dbailey75 » Mon Jun 24, 2013 1:02 pm

[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.

Support
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Re: Comparison Criteria - MD5 or SHA

Post by Support » Tue Jun 25, 2013 12:33 pm

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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