I'd love to see someone try. Here, an md5, those are super vulnerable right? This is a 9 character password. Piece of cake if I should believe the news.
f1f107c27cae21b5b5b01002e9c9ead8Using non-optimized, managed code on my laptop, I just went through 250 million iterations of plain text in ten minutes. You didn't specify what counts as a character, but let's assume it's a printable ASCII character. 95^9 = 630249409724609375 possibilities.
Divide by 250 million, and we get about 2520997639 times ten minutes for the time it would take me to enumerate all possible plain text passwords. That's a long time, about 47000 years. Not going to happen today on my laptop. But if I were a government, maybe I'd get a few thousand laptops together and set about calculating this over the next five years or so. In 1997.
But if I were to throw some purpose built hardware at this problem or use the video card to speed this up and not just laptops with general purpose CPU's, it's very likely I could decrease this time by thousands of times.
At the end I's have all MD5's for all passwords, and now the problem becomes a rainbow table lookup. And I only have to do this once and I forever gain the capability to break any 9 character (and below) password with just a lookup.
And that's assuming that MD5 is a perfectly secure hash with no shortcuts allowing you to narrow down the input set.
[1] https://www.wolframalpha.com/input/?i=%28630249409724609375+...
(Edit: Also being limited to alphanumeric for hashes and printable ascii for input gives you pretty good compression potential.)
Precomputed hash chains are a simplistic way of explaining how rainbow tables work. http://en.wikipedia.org/wiki/Rainbow_table#Precomputed_hash_...
Oh I thought you were going to say per second. I can recall reaching 500 MHash on some 2008 nvidia gpu with barswf.
Anyway, you're right of course. A nine character password is not really military-grade safe for countries with a security budget like the NSA's. But 9 characters ought to be many, orders of magnitude easier than 40 characters, and md5 is many orders of magnitude easier than pbkdf2 even at a weak security setting. This md5 might just be within reach of governments, but 40 characters certainly isn't.
For some fun performance figures, check http://golubev.com/gpuest.htm
A new AMD Radeon™ R9 295X2 is pretty speedy, clocking in at 23GHash for single MD5 (there are cheaper per $, but this is extremely impressive imo). Dividing 630249409724609375H by 23e9H/s leaves us with 27e6s, or 0.8 years. That means we'd need 42 cards to crack it in a week, costing somewhere in the region of $80k (1.5k/card + extras). That puts us easily within the range of governments, companies and just generally rich geeks. You can get ~ twice the hashes/$ so maybe $40k, and if you're cheap about the computers you connect with then probably lower.
But that's consumer kit. There are also speedy MD5 FPGA cores, I've not got a great reference but found one from 2007 which did 44MHash / core using a Cyclone II which I can only find described as "built for low cost". Assuming a 5x cost/hash reduction would grab us at $8k which would be in the range of hobbyists.
Beyond this, several private companies have been able to build double SHA-256 ASICs (for bitcoin mining). You could buy a while ago kit that did 7GHash for $300ish, and there's supposedly some 1THash ones in development. Granted, double SHA-256 is not equivalent to MD5, but I'd be surprised if MD5 was significantly harder, and expect it to be a lot simpler. Now the development cost of these is the expensive bit, but then your hashing rate would be insane.
Ramble over, if anyone has any figures for FPGAs or ASICs then I'd be really interested.
If you have a decent GPU, you can try several billion MD5 hashes per second: http://www.golubev.com/hashgpu.htm -- so if you stick with, um, lowercase alpha only should be crackable in under 10 minutes. If you choose from the 95 or so printable ASCII chars, you can expect a bit more of a wait (possibly a few years)... though of course if you don't restrict yourself to a single GPU you can speed things up.
Honestly, using an actually-random password that's more than 8 chars and not just alphanumeric offers decent security even when it's stored with a fast hash algo. Unfortunately, very few people do this in practice, and instead choose (for example) one of the 43 billion passwords in the md5 database here: http://www.md5decrypter.co.uk/
Fair enough. I'm still curious about the generation method though: I can imagine that testing all texts ever published takes $200k if you go up to 40 characters, but if you use a unique text it might be different. There are a lot of variables here, including honest misspellings, punctuation use, spacing (non-tech people seem to find spaces weird in passwords), capitalization, usage of names, etc.
It bugs me that even today, more systems (hello banks) don't support more open passwords. Even what's on a US Ascii keyboard would be nice. Two of my banks only support letters and numbers, no special characters and case insensitive.
I think while typing them in is when they are most susceptible to being stolen.
would be more appropriate