MD5 is a widely used cryptographic hash function with a 128-bit hash value. It is commonly used to check the integrity of files.

If you downloaded a file from the web and the file owner provided a MD5 hash

(checksum) then you can compare the hash of the downloaded file with the hash

provided by file owner. So you will know if you have downloaded the exact copy of the

file without any error.

And of course you can provide MD5 hash for your own files if you want.

Windows

In Windows I use an open source software HashCheck to MD5 hash verifying and

creating.

Download HashCheck from here then install it.

1, Verify the MD5 hash

HashCheck is a shell extension for windows explorer, it will add a "Checksums" tab

to the shell's file properties dialog so that you could easily check the hash of a file from

Windows Explorer.

In the following exaple I checked the hash of Joomla 1.5.6 to 1.5.9 upgrade patch file

with HashCheck.

 

As you can see in the above screenshot my copy of Joomla upgrade patch is correct.

If the file owner provided the MD5 hash stored in a checksum file such as file.md5,

just double-click on the checksum file, and HashCheck will check it.

2, Create a checksum file

You can also create hash/checksum file of your files with HashCheck.

Select the files and directories that you want to hash and create a checksum file for,

right-click on them, and select "Create Checksum File". Double-click on the

created checksum file and you will see the hash(es).

HashCheck supports the CRC-32 (in SFV format), MD4, MD5, and SHA-1 algorithms.

Linux

1, Verify the MD5 hash

In Linux the verifying process is more easy.

Open a terminal and type:

Press enter and you will see the MD5 hash. Compare it with the MD5 hash provided by file owner.

In my case:

The MD5 hash: 4e9e98fb058253f6f87d54fbcacf8466

My copy of Joomla upgrade patch is correct, see it on my Ubuntu Hardy desktop:

and make a test verifying