Now you are ready to burn your download image, but wait … are you sure that your download is error-free.  With the length of time that you waited for the download to finish, a hacker could have inserted malicious codes or virus within the iso image   that you are downloading.

An extra step that checks the authenticity and integrity of your download is required.  As of this writing, Ubuntu uses the MD5 (Message-Digest algorithm 5).  MD5 is a widely used, partially insecure cryptographic hash function with a 128-bit hash value.   As an Internet standard (RFC 1321), MD5 has been employed in a wide variety of security applications and is commonly used to check the integrity of files.  In addition, SHA (Secure Hash Algorithm) function is also used.

1. Download the latest version of MD5 for windows http://www.pc-tools.net/win32/md5sums/

2. Extract the program to your desired folder, I normally extract md5sums.exe in Windows system32 directory to free myself from having to bother about the location of the program, and creating additional path.

Drag the ISO image to md5sums

The Md5sums program will then compute for the MD5 value

Or, run the md5sums program from the command line. Change directory to the location of the ISO image, then run

md5sums ubuntu-9.04-desktop-i386.iso

Compare this value from the precomputed Ubuntu Md5.  The precomputed values can be found at  (https://help.ubuntu.com/community/UbuntuHashes).  Notice that the site shows different md5 values.  Check the value corresponding to the Ubuntu version that you downloaded.  In our case, we downloaded the i386 version.

If the computed value and the precomputed values are exactly the same, then it is time for you to burn the CD. Otherwise, repeat the download process.  Warning, do not burn the CD if the hash values are different as this may result in unpredictable errors during installation or implementation.

There are two options described here to burn the iso image file.

Burn the Installation CD using Nero

If you already have Nero, use this to burn the installation CD, otherwise download any burning software, i.e. infra_recorder. (http://infrarecorder.sourceforge.net/) or iso_recorder (http://isorecorder.alexfeinman.com/isorecorder.htm).

1. Point your mouse to “Copy and Backup” icon of the Nero main menu

2.  Click “Burn Image to Disc”

3.  Nero asks for the name of the iso image to be burned

4.  Select destination drive; input number of copies and click “Verify data on disk after burning”.

5.  CD-burn starts

6.  As soon as CD is burned, if the “verify disc after burning” is checked, Nero will proceed to “verify the copy”.  This ensures that burning is successful.  Failed CD burns could occur if the quality of the CD is low, has scratches, or interrupted by power interruption.

7.  Finally, “verification is completed”.  By clicking the “OK” button and smoothly exiting the process, the CD will be ejected automatically.

Another method of burning the image is using ISO Recorder.

ISO Recorder can be downloaded free from (http://isorecorder.alexfeinman.com/isorecorder.htm).  Following are the procedures for burning iso images using iso recorder:

1. Right-click on the image file that you want to burn.  Select “open with” from the menu, click “ISO record”.

2. The “CD Recording Wizard” window appears.  Verify that the name of the image file is written on the text box besides the “Image file” label.  Click on the “Next” button.

3. CD burn starts.

4. CD-burn continues …

5.  Wait until CD burn finishes, then click on the “Finish” button.