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Password Cracking Machine, affordably?


haze1434
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Hi all,

I can search this question on the internet and find the occasional useful byte of information, but most of it's a bit rubbish.

Plus, I'd like to get some direct opinions.

How would you personally go about setting up an affordable (say, less than $1500) Password hash cracking machine?

For example;

  • A computer packed with loads of cheap GPUs? But which ones?
  • A Raspberry Pi cluster?
  • Pay a service to do it for you? If so, what services are available?
  • Other?

Thanks.

*edited* My spelling and grammar is always terrible because I type too fast.

Edited by haze1434
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Cheapest way would be a cloud service, Azure or EC2 most likely, Rent the time and processing power you need and scale up and down at will, or albeit very naughty rent a botnet and use the "latent cpu cycles" to crunch the numbers.

If you wanted to have your own set up and have the "learning experience" of doing it yourself then,

I would most likely go for the PS3 (Version 1) in an array and use the YellowDog distro which was released for it.

Finding those machines would now be hard, but I think this is the most cost effective as old PS3's can be picked up for less than $150 on ebay, so you could set up 10 of them in an array and this would provide a nice set up for large number crunching.

IBM's CBM Cell processor in the PS3 was a mini super computer chip, There are many articles online about universities and even the US military playing with large numbers of PS3's to make "cheap" < $100K super computers.

$1500 will not build a super computer but its now most likely the cheapest bang for buck, However those machines crunching hashes would push your electricity bill up , but you'd never have to turn on the heating again , so that might offset the lecky bill :-)

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I would say for the 'buy some hardware' approach you're on the right track.

1. Clearly define the thing you need above everything else.

2. Find out which things provide that thing.

3. Get that thing, or repeat this list for that one thing.

You want to crack passwords, so you find out what tools are the most effective at cracking passwords under which circumstances. The conclusion is something like oclhashcat or pyrit or jack.

Since they all are very keen on using the GPU, find out which of them has the best performance on a given GPU, if possible in a multi-GPU configuration (often the benchmark results posted by people are... sketchy). There's you're winner for tool.

GPUs need a PC to be put in, so assemble a cheap machine so you know what part of your budget needs to go there and thus what part remains for the GPUs. If you have the budget for it, go for a machine that allows as many PCIe 1x cards as possible. I believe the maximum is 6 - remember, you don't need a lot of throughput from the cards to do this. A single PCIe lane will suffice.

Find out which GPU gives how much performance, and what each of those GPUs would cost you. Divide the performance number by the price of the GPU. See how many of those fit within your budget. Check to make sure the PSU can cope with their power draw.

If there's either some budget left, or you now have more GPUs than fit within your selected computer, see if going with the next one on the performance/price list still keeps you within budget. If so, verify the PSU can cope. Repeat.

Now that you've selected the GPUs, see if you can cramp down on the PC to run this. The CPU contributes relatively little, so skimp on that (but stay Intel!). Skimp on the harddisk (SSDs contribute nothing to the performance for this goal, so go with spinning rust), skimp on the mobo (the cheapest for the CPU socket with enough PCIe slots is fine. You can consider expandability by having at least 1 empty PCIe slot for an additional GPU in the future), skimp on the ram (both size, value and amount of slots on the mobo). Got some money left now? Go back to selecting GPUs, starting once again at the best-for-buck model and moving up from there.

End result: The best bang for your buck password cracking machine.

Do keep in mind that these things also have a running cost. Last I checked electricity is cheap but it isn't free, plus these things produce considerable heat which needs to go somewhere and potentially considerable noise which might bother people relevant in your life, not least of which is you yourself.

At 1500 you should be able to edge out a box with at least 3 GPUs in it.

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