Checking the integrity of a downloaded file

**Computer_Freak** · 30-01-2010

When you download large files or CD / DVD images, like Linux distributions, the publisher usually provides the fingerprint of file, also called the checksum or MD5 signatures. This checksum is a value calculated from the file and its corresponding checksum. During a download, especially if material, you're not immune, a disturbance or a network problem, which can corrupt the file you download. Data can then be damaged and to prevent software installation or its operation.

You can then, using the checksum provided by the vendor, verify that the file you downloaded is clean and without blemish. On Windows, you need to install software to control the MD5 signature of a downloaded file. Under Linux, the tools are present by default.

Under Windows Operating system WinMD5 is a free software that allows you to check the MD5 of your file.:

Download and unzip the file WinMD5.zip
Double click the file WinMD5.exe to launch WinMD5.
Confirm the launch of the software by clicking the Run button.
Next to the Filename field, click the button .
Select your hard drive to check the file and then click Open.
Click the Calculate button. The MD5 checksum is displayed.
In the comparison field, enter the MD5 signature provided by the author of the downloaded file.
Then click the Compare button.
The software then tells you if the file is clean (same checksum) or is corrupt (checksum mismatch). In the latter case, try downloading the file again.

Under Linux operating system md5sum can do the job that is usually integrated with your distribution.

Open the Terminal.
Navigate to the folder where the archive to check.
Then enter the following command: md5sum filename replacing filename with the name of the archive and then press the Enter key.
The MD5 signature is displayed. Compare it to that provided by the author of the downloaded file. If the signatures are identical, the file is clean, otherwise it is corrupt.

**Computer_Freak** · 30-01-2010

If you want to distribute software, document, video, short, any type of files you can generate MD5 signature. By communicating with people downloading the file, they can check it for completeness. Here is how to do that:-

On Windows, just run WinMD5.
Next to the Filename field, click the button .
Select your hard drive to check the file and then click Open.
Click the Calculate button. The MD5 checksum is displayed.
Linux, open a terminal.
Navigate to the folder where the archive to check.
Then enter the following command: md5sum filename replacing filename with the name of the file you want to calculate the MD5 and then press the Enter key.
The MD5 signature is displayed. Rate it.