Compared with their CPU counterparts graphics processing units (GPUs) significantly (up to 60 times!) accelerate the process of Microsoft Office 2007 - 2010 password recovery. The difference is stunning. Where's the trick?

In two minds: choosing the right helper

Actually there is no magic, and you will see that on a very primitive example.

Imagine you are in charge for your kid's wedding party and you need to make hundreds of phone calls inviting relatives and friends. Such an important mission would be way easier accomplished if you had a couple of assistants.

The CPU Int. company offers you 4 of its most efficient employees speaking all the languages known to man while the GPU Ltd. is ready to help you out with 800 staff-members capable of speaking one language only. And both companies sell their services at nearly the same price.

So who you think is going to be the first to phone this whole lot of people? The guys from GPU Ltd. have to make just one call each while each member of CPU Int. has to make 250 phone calls. The answer seems quite obvious. But let's not rush. It's not that easy.

If your kid's beloved and the GPU guys share the same language then it's OK and they're going to win for sure. But what if the newlyweds speak different languages? This would definitely raise the chances of CPU Int. They are polyglots, you remember?

This is just an example but it is based on real events.

Modern CPUs have 4 cores. They can process data by working at multiple tasks in parallel (like make "phone calls" in 4 different languages at a time). Whereas graphics cards have up to 800 data flow processors but they only work together at one and the same task i.e. "call" 800 people speaking one language. It turns out that when you split a task into many homotypic ones graphics cards are outpacing CPUs.

Office 2007/2010 passwords recovery is just the right task to be solved with the GPU acceleration!

Office 2007/2010 passwords

In its latest editions of Office the Microsoft developers have modified the file format. Protection algorythms have also been changed. Without going deep in detail about the increased 128-bit key, shift from RC4 to AES or change of functions from MD5 to SHA1 with increased number of iterations there's one thing we can say for sure: there's been a great slowdown in CPU-based password recovery.

For example the leader of the performance test Accent OFFICE Password Recovery (Basic Edition) working on Intel Centrino Duo 2GHz computes 1.700.000 variants per second for Office 2000 and only 370 (!) for an Office 2007 document.

Modern CPUs are not ready for the amount of homotypic data to be computed while searching for an Office 07/10 password. While graphics cards ARE ready to handle it! The amount of data is more than sufficient so that all the card's processors may be assigned with a task.

However not all graphics cards can be used by GPU-based password recovery. The card must support GPGPU function (general-purpose GPU). The most popular ones are NVIDIA CUDA and ATI Stream.

Leading technologies

It all began in early 2000s when performance characteristics of graphics cards started to grow exponentially. Then came motherboards supporting more than one card in a computer. That enhanced computational functions of an ordinary PC putting it side by side with the first supercomputers. It would be strange to use them just for games, wouldn't it?

Another important milestone was public release of CUDA by NVIDIA in 2007. The technology turned out to be very friendly and perfectly documented. A bit later that same year AMD/ATI - the biggest NVIDIA's competitor - presented its quite complicated technology ATI Stream. What followed was like an avalanche.

The new tools and supplementary documentation were warmly welcomed by developers from around the world. New software appeared, older one was improved. Implementation of graphics cards in complicated calculations, editing video files, exchange quoating or GPU-based password recovery affected productivity and made it soar which found universal acclaim among users.

Who's the best anyway?

Accelerated GPU-based recovery of passwords to Office 2007/2010 is the most advantageous way to regain a lost password. That is true but which graphics card is the fastest of all? To find that out we have measured their speed characteristics by recovering passwords to open a Microsoft Excel 2007 file. Here is what we got:

Name Number of cores Price (approx.) Speed (passwords per minute)

Atom 330 2 $80 232

AMD Athlon X4 9550 4 $150 768

Intel Core 2 Q6600 4 $400 1100

NVIDIA GTS250 128 $150 3250

NVIDIA GTX260 216 $300 3400

NVIDIA GTX295 240 $600 8500

ATI HD4770 640 $120 6800

ATI HD5770 800 $170 13200

ATI HD5970 3200 $650 44000

While NVIDIA has nothing to offer the absolute leaders of the race are ATI products. They are also on top of the price rating where ATI is uncompromisingly championing with its HD5970.

So it's clear now that the secret of the GPU accelerated password recovery consists in an ATI graphics card and a program that can trigger all its capabilities.

A copywriter-freelancer. He creates articles and reviews in the field of software. Understanding of software development fundamentals and studying of application environment allows receiving high-quality texts.