File download and md5 ?

[saidbakr]

Hi,

Sometimes when I do download for a file, I notice something about md5 hash for the downloaded file. What's the relation between encryption and downloading a file? What's the importance of this value of md5 for downloading a file and how does it obtained?

[bradgrafelman]

MD5 checksums have nothing to do with encryption. Some sites offer MD5 checksums for the files they offer simply so that you can ensure the file's validity after downloading it. There are many free tools out there to determine the MD5 checksum of any file (you could even write a simply PHP script to do it.. it'd take 1 line to do).

All you do is compare the MD5 hash of the file you've downloaded with the "valid" hash provided by the site you downloaded the file from. If there is a mismatch, either the file was compromised or the download was interrupted/corrupted.