What is MD5 Hash and How to Use it

In this post, I will discuss about one of the interesting cryptographic algorithm calledMD5 in a very simple and easy to follow manner. In addition to understanding what is MD5 hash, you will also learn how to make use of this algorithm in your daily life.

What is MD5 algorithm?

MD5 which stands for Message Digest algorithm 5 is a widely used cryptographic hash function that was invented by Ronald Rivest in 1991. The idea behind this algorithm is to take up a random data (text or binary) as an input and generate a fixed size “hash value” as the output. The input data can be of any size or length, but the output “hash value” size is always fixed. Here is an example of MD5 Hash function at work:

As you can see from the above example, whatever the input size you give, the algorithm generates a fixed size (32 digit hex) MD5 hash. You can even try this on your own using the MD5 hash generator tool here.

Applications of MD5 Hash:

Before I tell you about how to use MD5, I would like to share one of my recent experience which made me start using MD5 algorithm.

Recently I made some significant changes and updates to my website and as obvious, I generated a complete backup of the site on my server. I downloaded this backup onto my PC and deleted the original one on the server. But after a few days something went wrong and I wanted to restore the backup that I downloaded. When I tried to restore the backup, I was shocked! The backup file that I used to restore was corrupted.

That means, the backup file that I downloaded onto my PC wasn’t exactly the one that was on my server. The reason is that there occurred some data loss during the download process. Yes, this data loss can happen often when a file is downloaded from the Internet. The file can be corrupted due to any of the following reasons:

• Data loss during the download process, due to instability in the Internet connection/server.
• The file can be tampered due to virus infections or
• Due to Hacker attacks.

So, whenever you download any valuable data from the Internet, it is completely necessary that you check the integrity of the downloaded file. That is, you need to ensure that the downloaded file is exactly the same as that of the original one. In this scenario, the MD5 hash can become handy. All you have to do is generate MD5 hash (or MD5 check-sum) for the intended file on your server.

After you download the file onto your PC, again generate MD5 hash for the downloaded file. Compare these two hashes and if they match, that means the file is downloaded perfectly without any data loss.

A MD5 hash is nothing but a 32 digit hexadecimal number which can be something as follows:

e4d909c290d0fb1ca068ffaddf22cbd0

This hash is unique for every file irrespective of its size and type. For example, two different executable files (.exe files) with the same size will not have the same MD5 hash even though they are of same type and size. So MD5 hash can be used to uniquely identify a file. The same thing applies even for messages where each message that was sent and received can be verified using the MD5 hash.

How to use MD5 Hash to check the Integrity of Files?

Suppose you have a file called backup.tar on your server. Before you download, you need to generate MD5 hash for this file on your server. To do so use the following command:

For UNIX:

md5sum Fun.tar

When you hit ENTER you’ll see something as follows:

e4d909c290d0fb1ca068ffaddf22cbd0

This is the MD5 hash for the file backup.tar. After you download this file onto your PC, you can cross check its integrity by again re-generating MD5 hash for the downloaded file. If both the hash matches then it means that the file is perfect. Otherwise it means that the file is corrupt. To generate the MD5 hash for the downloaded file on your Windows PC use the following freeware tool:

MD5 Summer

I hope you like this post. For further doubts and clarifications, please pass your comments. Cheers!

Durandal v0.5: CPU/GPU Hash Cracker

Durandal is a distributed GPU/CPU computing software that aims to crack passwords. Mostly written in C++ with the Boost library, it works on many systems, however it is only buit for Windows and GNU/Linux for the moment x64 platforms.

Durandal can be used for:

1. OS portability: It works and has been tested on Windows and GNU/Linux, but could work on *BSD, Solaris, or any other platforms that support C++ and the Boost library.
2. Architecture Pertability: hash functions aren't only developped in SSE2 assembly and Nvidia CUDA; there is also a C version that could be ran on any architecture.
3. Powerful: by using C++, Durandal has been designed in order to support a lot of computers.
4. Performance: has functions are optimized with SSE2 for CPUs and ported to Nvidia CUda for GPUs.

Features of Durandal

• Windows (XP, Vista, 7) and GNU/Linux support
• 64bits support
• Usual hash fuctions: MD5, SHA1, SHA256, SHA512, NTLMv1, MySQL (all versions)
• SSE2 optimized, Nvidia CUDA support
• Server, agent and administration console
• Network communication with XML over HTTP (proxy support)

Download Durandal v0.5 from here: Download

BarsWF - Worlds Fastest MD5 Hash Cracker

The MD5 Message-Digest Algorithm is a widely used cryptographic hash function that produces a 128-bit (16-byte) hash value, Md5 is an encryption that cannot be reversed, the only successful way to find out the content of a md5 hash, is by running a Brute force Attack


BarsWF Worlds Fastest MD5 Hash Cracker 
Barswf is a program designed to crack md5 hashes. It combines old with newer CUDA technologies. So, it uses your graphical card and if available, multiple cores to manage the cracking of md5 hashes. It's considered to be  the fasted Md5 Hash cracking tool available.

System Requirements

• CUDA version only:nVidia GeForce 8xxx and up, at least 256mb of video memory.
• LATEST nVidia-driver with CUDA support.Standard drivers might be a bit older (as CUDA 2.0 is still beta)
• CPU with SSE2 support (P4, Core2Duo, Athlon64, Sempron64, Phenom).
• Recommended 64-bit OS (WinXP 64 or Vista64). 32-bit version is also available.

Download 

AMD BROOK Beta 0.9:
BarsWF Brook x64
BarsWF Brook x32

CUDA 0.B:
BarsWF CUDA x64
BarsWF CUDA x32

SSE2:
BarsWF SSE x64
BarsWF SSE x32 


Tutorial

The following video shows us how we can crack MD5 hashes using BarsWF

If you have any doubts regarding the post , Please let me Know them via comments

How to crack MD5 hashes

MD5 is not an encryption, and therefore cannot be decrypted, only cracked.


First off, download "Password Pro" from here.
It is a zip file, so I suggest downloading 7zip.
Extract all of the files to one folder.
It should look similar to this.


For the purpose of this tutorial, I will be cracking this hash: "6dcd0f272fbb7f6f8ff3a8a5e96c45aa:Ws)", which is formatted as "Hash:Salt", and is from VBulletin 4.x.x.

Open up notepad, paste in the Hash and salt, and save it anywhere on your computer, preferably in the same folder as Password Pro.



Open up Password Pro and go to "File->Import"


Find the place where you saved the text file with the hash inside of it, and open it.
Fill in the boxes as such.

Note: The bottom is the formatting of the hash and salt in the text file, and the top is the algorithm for VBulletin 4.x

Now, go to "Audit->Preliminary Attack"
(For this hash, as it is simple, it should probably crack it with just this.)

Hit the start button, and watch it go.



If, in the case that a Preliminary Attack does not work, just repeat the previous steps with a Rainbow Attack (If you have a Rainbow Table), a Simple Dictionary Attack, or a Brute Force Attack.