Every time you download a file from the internet, whether you are surfing the web or you are using Skype to get that file, you should always the check the integrity of the file. Why? How to check data integrity on Windows easily.
Check the integrity of a file means verify whether the downloaded file is the actual same file that has been sent from the source directly to you (the destination), and no one was in the middle to change same byte or even critical informations.
Normally the data integrity is checked using a digest comparison, a hash code (or, in other words, a string) which is pre and post computed and the two different values are compared. If they are the same everything went smooth.
How can we achieve this if we have Windows?
No worries, because we need to have two things:
a) the digest published by the source
b) a program to calculate again the digest, this time by ourselves.
As regard the point a), if we are receiving the file from a friend, and we are talking with Skype, we need to ask him to calculate the digest manually and show it to us using the chat. Our friend can calculate the digest manully using one of the software proposed at point b).
As instead regard the point b), for you I have two suggestions as programs used to compute the digest:
i) use the windows CertUtil pre-installed tool (command-line based)
ii) install 7-Zip, which also contains well integrated algorithms for digest computation.
Let’s see them in detail.
Syntax: CertUtil -hashfile FileName HashingAlgorithm
FileName is the filenamePath you want to access,
HashingAlgorithm is one of the following value: MD2 MD4 MD5 SHA1 SHA256 SHA384 SHA512.
You only need to download the file, right-click of the mouse on it, and search for the neeeded hashing algorithm.
Ultimately, 7-Zip is the most user-friendly tool, and if you are not comfortable with the terminal and command-line interfaces, choose it.
One more thing: if for some reason you heard about it, I discourage you to use the FCIV Windows tool, since it relies on the computation of only a subset of all the possible hashing alghorithms, and also work with the most oblesete ones: MD5 and SHA-1.