md5 Checksum

[mag046]

I have searched and found quite a bit on checksum verification, my only problem is that I dont quite understand how it works.

I downloaded RedHat 8 and wanted to verify my .iso(s) like they suggested.

I understand that I need to compare the md5 check output with the md5sum string? I downloaded the md5sum file that was in the folder with the 5 .iso(s). Now Im not sure what to do. I do not know how to "acquire" the checksum for the .iso(s). And then how do I compare it to the md5sum file I downloaded?

Im just kinda confused at this point, I have downloaded Advanced Checksum Verifier 1.2.0. It keeps telling me that md5sum does not appear to be a valid file. I gather that this is because it doesnt have an extension?

I did successfully run Adv. Checksum Verifier on my Mandrake 9 .iso(s) but I do not understand the output that it displayed on the screen.

Maybe someone could point me in the right direction?

Thanks...mag046

 

[mag046]

I have since learned this...

MD5 files are a calculated value based on a set algorithm of a file or set of files. This "checksum" can be calculated and saved to an .md5 file using any one of many programs available.

Due to my lack of knowledge and understanding of the process (as a whole), I have abandoned Advanced Checksum Verifier. I am not "Advanced" enough at my current knowlege level to understand and use this program effectively.

Upon investigating further, a forum member posted about Easy MD5 Creator. It can be found here:

h**p://www.therudeone.com/ftp/applications/easy_md5_creator/

It was very straight-forward and even I (as a complete newbie) could use and understand this app. It was self explanitory and I could understand what it was doing while it was doing it.

I then used it to verify my Mandrake 9 .iso(s)...perfect, verified against the md5sum.90 file. I am gathering that the sum files can possess any sort of extension. I did not alter it in any way and emd5c recognized the .90 file and verified off it perfectly.

I then attempted to verify my RedHat 8 .iso(s)...not-so-perfect. emd5c found 14 references in the MD5SUM file I downloaded from the .iso directory. Of these 14, 5 were my RedHat 8 .iso(s) I needed. The .iso(s) verified perfectly, but there was a bunch of other "references" in the file.

I opened the MD5SUM file with Notepad and it referenced PGP. I am gathering that the MD5SUM file might need to be further processed because it is protected from alteration by PGP.

Here is the actual file contents as viewed by Notepad:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

d7b16b081c20708dc0dd7d41793a4177 psyche-i386-disc1.iso
2df17bc02cb1b3316930ed4f7601ad9e psyche-i386-disc2.iso
305d6ff5b5850fa316276710a148b0a3 psyche-i386-disc3.iso
0a77d7a3bc8c4e87508c46a2670242eb psyche-i386-disc4.iso
8dbcf16f0072ee47db49b08921a41ba5 psyche-i386-disc5.iso
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org

iD8DBQE9mH6DIZGAzdtCpg4RAkKnAJ9FoKBr0tTIakp9XEn+3+jEWkES2QCfbVBo
OFisZU8vsf6HHUpUivNv39I=
=J1G1
-----END PGP SIGNATURE-----

I have learned how to check the md5sum based on a native .md5 file, but I am sure that I will run into others. If anyone would like to provide an insight, please do...just thought I would share what I learned, even if I dont quite understand it 100% yet...

later...

 

[lotusfang]

As you have stated md5 is a checksum generation algo. The Symantec Anti Virus Updates are checksummed using md5 algorithm.

http://securityresponse.symantec.com/avcenter/download/pages/US-N95.html

In this case, they generate the checksum for each of the files which can be downloaded and store these values in a text file along with the filename. I have been using the same to verify data integrity of the updates.

The below link takes you to the site which contains the md5 generator used. The source code for the same is also available along with the binary. You can check it out at-

http://www.fourmilab.ch/md5/index.html

Hope this (esp. the algo. source) is helpful.

- LF

 

[mag046]

Thanks for the info, it is much appreciated. I definitely learned somthing from that link...

I also learned a new way to post non-active links in the forum without altering the actual link. The way you did it, there is no need to edit the link after pasting it...thanks again.

My .iso(s) work perfectly, just working on the box to load that OS on now. Im anxious to see how the new versions work...

Thanks...