How to check the integrity of a program or a file in a simple and safe way
The MD5 and the SH1 are two strings 32 and 40 characters long respectively which have the particularity of being, after performing a checksum or hashing operation, to have a unique value for values, files, or installation packages. Their use is necessary if we want to guarantee users who download our software that our installation package has not been counterfeited by malicious third parties.
Usually (not always) when we download free tools, whether or not they are open source, the download of the installer is associated with an MD5 string, or checksum, which indicates the MD5 value of that installer calculated directly by the person who compiled the file you are to download. Before running the installation we should check the MD5 of that file, so as to be able to check if it coincides with what was communicated by the developer of the software.
If the checksum is different, it means that someone has forged the file and it may also contain malicious code. If the MD5 matches, it means that this is exactly the installation file released by the software developer.w
How do I calculate the MD5 of a file?
Nirsoft, producer of numerous tools, also distributes HashMyFiles for free, a very useful small tool that allows us to calculate the checksums of multiple files massively. It integrates with the Windows context menu, and allows you to massively copy or export multiple calculated checksums in order to check the actual authenticity of any file.
Available only for Windows, it is compatible from the XP version until today, therefore it can also be used by those with older systems.