Project 9: MD5 Collisions (15 pts.)

What You Need

Purpose

MD5 is a widely used hash function, despite the fact that it suffers from known collisions. This project will demonstrate that two very different files can have the same MD5 hash.

Downloading and Installing HashCalc

Open a Web browser and go to

http://slavasoft.com/hashcalc

On the upper left, click the blue "Hashcalc 2.02" link. Save the Zip file on your desktop.

On your desktop, right-click the hashcalc.zip file and click "Extract All" Click Extract.

A hashcalc window opens containing a setup.exe file. Double-click the setup.exe file and install the software with the default options.

Downloading and Installing the Hello.exe and Erase.exe Files

In a Web browser, go to

http://www.mscs.dal.ca/~selinger/md5collision

Scroll down to the section titled "An evil pair of executable programs", as shown below.

Click the hello.exe file. Save it on your desktop.

Click the erase.exe file. Save it on your desktop.

Running the Files

Normally a MD5 hash is used to verify that a file has not been altered. If two files have the same hash value, they are expected to be identical.

On your desktop, double-click the hello.exe file. If an "Open File - Security Warning" box appears, click Run. A box opens saying "Hello World", as shown , as shown below.

On your desktop, double-click the erase.exe file. If an "Open File - Security Warning" box appears, click Run. A box opens saying "This program is evil!!!", as shown , as shown below.

Saving the Screen Image

Make sure the "This program is evil!!!" message is visible.

Press the PrntScrn key to capture the whole screen.

YOU MUST SUBMIT WHOLE DESKTOP IMAGES FOR FULL CREDIT.

Save this image as a PNG file, named "Proj 9a from YOUR NAME"

Calculating the Hash Values

Click Start and type in HASH

In the search results, click HashCalc.

A gray HashCalc box opens.

Drag the hello.exe file from your desktop and drop it in the HashCalc window. The MD5 hash appears, ending in 007, as shown below.

Drag the erase.exe file from your desktop and drop it in the HashCalc window. The MD5 hash appears, ending in 007, as shown below on this page. Notice that the MD5 values are identical for the two files, but the SHA1 hashes ar different. SHA-1 is a much better hash function than MD5, having no known collisions at the time of this writing (Feb. 9, 2016). However, SHA-1 collisions are expected to be found this year, so many people are now updating to SHA-2.

Saving the Screen Image

Make sure the MD5 hash ending in 007 is visible.

Press the PrntScrn key to capture the whole screen.

YOU MUST SUBMIT WHOLE DESKTOP IMAGES FOR FULL CREDIT.

Save this image as a PNG file, named "Proj 9b from YOUR NAME"

Turning in Your Project

Email the images to cnit.120@gmail.com with a subject of "Proj 9 from YOUR NAME".

Last modified 2-17-16