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I am attempting to install a VMware Fusion virtual machine with Windows 2008 R2 server, but I'm having problems with the ISO file I downloaded.

I want to verify that the file is correct before attempting the installation, and the download page at Microsoft MSDN downloads mentions that the file has a SHA-1 checksum of X.

So, I googled on how to verify the SHA-1 digest for a file, and found this page:

Mac OS X: How to verify a SHA-1 digest
... openssl sha1 [full path to file]

Now, here's the fun part. If I execute the command multiple times, I get different digest values.

Is there any way I can, say, make a copy of the file (I know how to do this part), verify that the two copies are indeed the same (to detect that the file is changing, somehow, but I don't know how to compare files)?

Or is there something fundamentally broken either with the "openssl sha1" command, or with my expectations of it?

Here's a sample run:

Lasses-MacBook-Pro:Downloads lassevk$ openssl sha1 en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso  
SHA1(en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso)= 6b8e9addd77fdaf7f26ca56729802112445d48ec
Lasses-MacBook-Pro:Downloads lassevk$ openssl sha1 en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso  
SHA1(en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso)= db275e4640a61cf4021142bed7593390ebb1bc74
Lasses-MacBook-Pro:Downloads lassevk$ openssl sha1 en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso  
SHA1(en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso)= a87acbd3b415440630251ca1f66ed64e444ae96f
Lasses-MacBook-Pro:Downloads lassevk$ ls -la en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso  
-rw-r--r--@ 1 lassevk  staff  3166584832 Dec 12 01:02 en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso
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Unfortunately I can't add appropriate tags to this question due to my low reputation. If someone could retag it with some more appropriate tags, like "openssl sha-1" or something, that'd be nice. –  Lasse V. Karlsen Dec 12 '11 at 0:19
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1 Answer

This was a faulty memory chip.

I downloaded a program to test the memory, experimented with which chips it might be, and ended up removing one, which made the memtest program stop complaining.

When I execute the "openssl sha1" command now, multiple times, it produces the same digest every time. Sadly, it's the wrong digest (as compared to the one posted on the web site), so I guess I have to redownload the file.

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