"Why I'm releasing a brainwallet cracker at DEFCON 23"

[bitpump]

"Why I'm releasing a brainwallet cracker at DEFCON 23"
https://rya.nc/defcon-brainwallets.html
https://twitter.com/ryancdotorg

The 250BTC Brainwallet passphrase was "how much wood could a woodchuck chuck if a woodchuck could chuck wood"
https://twitter.com/ryancdotorg/status/629862282831511552

Slideshow
https://rya.nc/cracking_cryptocurrency_brainwallets.pdf

Software
https://github.com/ryancdotorg/brainflayer

More details on this topic:
https://www.reddit.com/r/Bitcoin/comments/3g7bpa/brainwallet_shut_down_permanently_due_to/

[electerium]

this is actually like unbelievably horrible, and troublesome.

I remember when i first read about brainwallet on reddit I thought: that's like really scary, but cute, a lot of people will fall for using it.


It never occurred to me that not only could people end up with the same passphrase, but that you could actively scan the entire blockchain and just start brute forcing for brain wallets with easily gussed passphrases.


What's most concerning are that there are people who are ALREADY running botnets on the blockchain, and today any 5 char passphrase gets auto extracted in seconds.


most poignant:

"Brainwallets make the Blockchain a
public password hash database"

[AgentofCoin]

...
The 250BTC Brainwallet passphrase was "how much wood could a woodchuck chuck if a woodchuck could chuck wood"
https://twitter.com/ryancdotorg/status/629862282831511552
...

It is surprising to me that people who are knowledgeable enough about Bitcoin/bitcoin to know what a brainwallet is,
don't choose more complex phrases, especially when their bitcoins are at higher risk of theft, compared to a standard privatekey.
The "how much wood could a woodchuck..." saying or whatever it is considered could be chosen by tens of people, in theory.
With millions of users in the future, that one would pop up hundredths of times.

Good luck with your presentation.

[electerium]

people whove used brainwallet should sha256 their passphrase immediately and move the coins to something more secure.

[LiteCoinGuy]

alot of smart people recommended that you should not use a brainwallet.

thanks to the reseacher. actually he is a whitehat  


@AgentofCoin

that is truly a bad brainwallet 

[findftp]

people whove used brainwallet should sha256 their passphrase immediately and move the coins to something more secure.

Uhm, you're joking right?

[cellard]

Damn, how I didn't think about that one? there's probably a lot of money being held with simple ass phrases like that, people just don't take their security seriously enough. Hopefully with time they will learn.

[CelestialWalrus]

The 250BTC Brainwallet passphrase was "how much wood could a woodchuck chuck if a woodchuck could chuck wood"

I've tried guessing some of them, but this one is just... wow. I've never found anything actually.

[Kazimir]

I have a LOT of bitcoins stored in brainwallets, and I feel perfectly safe about it.

I think brainwallets are very secure, provided that you REALLY understand what makes strong input for a brainwallet, and what doesn't.

For example, I use Sha256²(master key + passphrase) where "master key" is a long, complex, impossible to guess password that I also use for e.g. Keepass. And the passphrase (it's actually a phrase, not a word) is something I can remember easily, but is still kinda hard to guess. Together, I feel very confident that nobody on earth is ever going to guess or brute force it.

With Sha256² I mean something similar to Sha256d (double Sha256) which Bitcoin uses, but instead of Sha256(Sha256(x)), I use Sha256(x+Sha256(x)).

[jonald_fyookball]

I have a LOT of bitcoins stored in brainwallets, and I feel perfectly safe about it.

I think brainwallets are very secure, provided that you REALLY understand what makes strong input for a brainwallet, and what doesn't.

For example, I use Sha256²(master key + passphrase) where "master key" is a long, complex, impossible to guess password that I also use for e.g. Keepass. And the passphrase (it's actually a phrase, not a word) is something I can remember easily, but is still kinda hard to guess. Together, I feel very confident that nobody on earth is ever going to guess or brute force it.

With Sha256² I mean something similar to Sha256d (double Sha256) which Bitcoin uses, but instead of Sha256(Sha256(x)), I use Sha256(x+Sha256(x)).

Yes.  However, it seems most people don't REALLY understand that.  It seems simple and obvious to
an informed person, but it is not to the layperson, even when explained.

In another thread, we were discussing probabilities and someone remarked "I don't understand all this fancy math"
when there was no math involved except multiplication and perhaps exponentiation.

When you're smart/informed/talent, its easy to overestimate the abilities of others.  So,
I get why brainwallets aren't recommended and even in your situation, the entropy can
only be estimated but not measured directly.

I just use electrum although I do believe in theory that you're right.  If you truly know
what you're doing, you can create a strong brain wallet.

[Mickeyb]

people whove used brainwallet should sha256 their passphrase immediately and move the coins to something more secure.

Come on man, people who know how to choose good passwords and store them correctly while using brainwallets are as safe as using other "normal" wallets. I have seen so many stupid missuses with the wallet.dat files so far that are as bad as bad brainwallet passwords.

This means nothing, if people are using brainwallets, they are not less safe automatically.

[EternalWingsofGod]

With the issues of setting up an intelligent brainwallet, it makes sense that people would be better off not creating them unless aware and capable of securing them however if the wallet is unused and abandoned a few treasure troves are available for grabs.

The 250BTC Brainwallet passphrase was "how much wood could a woodchuck chuck if a woodchuck could chuck wood"
Someone didn't think that over.

[coinableS]

I have no plans on ever using a brainwallet when there are much more secure ways to store my coins.
If I did decide to use one for some crazy reason I would include a salt and a separator symbol.

"Im@b34v3r^how^much^wood^could^a^woodchuck^chuck^if^a^woodchuck^could^chuck^wood"

[jonald_fyookball]

the really sad part is that this nursey rhyme is maybe forever ruined for the victim.

[Soros Shorts]

The 250BTC Brainwallet passphrase was "how much wood could a woodchuck chuck if a woodchuck could chuck wood"
https://twitter.com/ryancdotorg/status/629862282831511552

Next we'll hear about some moron using as a passphrase "peter piper picked a peck of picked peppers".

[GermanGiant]

As it seems, the Github source code of the brainwallet.org has also been taken down. Does anyone know about a copy of that repository ?

[Herbert2020]

The 250BTC Brainwallet passphrase was "how much wood could a woodchuck chuck if a woodchuck could chuck wood"

i don't mean to be harsh but honestly if the passphrase of the brain wallet was "how much wood..." the owner deserves to lose 250BTC and more.
the first thing that the brainwallet itself in the password field suggests is not to use popular phrases.
https://www.google.com/search?q=how+much+wood+could+a+woodchuck+chuck+if+a+woodchuck+could+chuck+wood

there is even a film with the same name for gods sake!
https://en.wikipedia.org/wiki/How_Much_Wood_Would_a_Woodchuck_Chuck_(film)

[manselr]

I think this is a good thing. We must be exposed to all of the possible Bitcoin and Bitcoin related stuff flaw's as early in the game as possible. Imagine if this happened 10 years from now. Now we can afford taking big losses and big mistakes because we can fix them without much impact, since we are still very early on.

[bitcoinmasterlord]

...
The 250BTC Brainwallet passphrase was "how much wood could a woodchuck chuck if a woodchuck could chuck wood"
https://twitter.com/ryancdotorg/status/629862282831511552
...

It is surprising to me that people who are knowledgeable enough about Bitcoin/bitcoin to know what a brainwallet is,
don't choose more complex phrases, especially when their bitcoins are at higher risk of theft, compared to a standard privatekey.
The "how much wood could a woodchuck..." saying or whatever it is considered could be chosen by tens of people, in theory.
With millions of users in the future, that one would pop up hundredths of times.

Good luck with your presentation.

That is unbelieveably. With that amount of coins on it it must have been an experienced bitcoiner. That he made such an error makes it hard for me to feel pity for him.

Guess bitcoiners don't actually need to know about security.

[Financisto]

The facts of this research are outstanding...

That's why I only rely on KDF (scrypt, bcrypt and PBKDF2), never fast hash functions (SHA family etc) for this purpose (Brainwallets).

Thanks for your educational work! The community just gets stronger with it!