Bitcoin Forum

As you all are most likely aware of, it is possible to import any SHA256 hash as a bitcoin wallet private key. You can generate SHA256 hashes on this website: http://passwordsgenerator.net/sha256-hash-generator/

Is it possible to check on an offline computer which bitcoin address it corresponds to? I'm thinking about creating a brain wallet on an offline machine to store bitcoin on. Thank you for any help :)

A Hero member... that has never heard of bitaddress.org (https://www.bitaddress.org/) or bitcoinpaperwallet.com (https://bitcoinpaperwallet.com/)... or the fact that brain wallets are a really really REALLY bad idea?  :o  :P  ::)

Both of those sites will even let you just enter a "brain wallet" phrase and do the SHA256 hash as well... They also both provide downloadable versions that you can use on an offline machine

No, you can't just make a hash out of a password, smack it into any client and expect it to work.

These are the steps to convert it into a private key: https://en.bitcoin.it/wiki/Wallet_import_format. That being said, its incredibly insecure to generate an address using SHA256 since its rather fast to bruteforce tons of address with weak to moderate passwords.
Yes, there are various scripts to do so, eg. Bitaddress.org.

I really cannot recommend anyone generating an address with a password and expecting it not to be compromised in a short time. You can generate addresses on Bitaddress.org, don't use the brainwallet function.

If you do want to make some sort of brain wallet, use WarpWallet (https://keybase.io/warp/warp_1.0.9_SHA256_a2067491ab582bde779f4505055807c2479354633a2216b22cf1e92d1a6e4a87.html) (the page can be downloaded and used offline). It uses a proper hardened hash (mix of SHA256 and scrypt with 64k and 512k iterations respectively), so brute-forcing warpwallet passwords is very, very slow. Besides, warpwallet passwords are seeded, so any bruteforcing will have to be targeted, i.e. hackers will have to know your seed (email) and they'll have to attack just your password specifically, and not ALL of brainwallets at once.

Thanks for the input guys!

If you use bitaddress.org, you should generate the key under an operating system that uses isolation techniques to guarantee that the OS is no infected with any malware and whatnot.

Tails is very easy to install. I have only used it to create paperwallets. Just put Tails in a DVD, launch it and after it boots just open the browser, go to bitaddress, then turn off your modem and generate the key, that's all.

Download the website of brain wallet generator and close the internet connection and create one.

I would not advise using brainwallet, they are bruteforcecrackable (Unless you use a 14+ char password, but it would be possibly crackable in the future).

As the other here have already said, just to reinforce their points even more strongly - using a brain wallet would be a very, very bad idea indeed. There are many videos you can watch on YouTube which will walk you thorugh exactly how to make paper wallets including my personal favorite here: https://www.youtube.com/watch?v=872eSnlKUeg which walks you through how to make a paper wallet using bitaddress.org OFFLINE, so that no one can possibly view the keys that you generate except you. The only way is if you already have malware/viruses on your device, which would allow hackers to hijack it and steal your secret key. And yeah I am surprised that you are a Hero Member and did not know this already. :s

see my gocoin wallet.
http://gocoin.pl/gocoin_manual_wallet.html
http://gocoin.pl/gocoin_manual_spending.html

in your case, you'd have to convert the SHA256 values into the private key base58 encoded strings and put them into .others file.

but you can also just feed the wallet with a memorable seed password and it will create 250 deposit addresses for you.
just remember that my algo of calculating the hash (private key) is different.

then you use the same software to spend your coins (sign transactions) at an offline pc.
for that you will also need a tool called "balio" (assuming you don't want to run gocoin node).

why this is a bad idea: https://bitcointalk.org/index.php?topic=311000.msg3345309#msg3345309

I can refer you to articles saying that using bitcoins in general is a bad idea because you don't know what you're doing and therefore you can easily loose your coins.  

Obviously, if you don't know what you're doing you can easily loose your coins - it doesn't take a genius to figure that out.  

If you do know what are you doing, at the other hand, and if you know what you want, brain wallet might be just the best way to go for you.
Which my and my friends'  brain wallets have proven true for years.

So cut off the crap as I'm quite tired already listening to this dogmatic bullshit that you dare to call 'research'.

I have to agree here.  Brain wallets are a bad idea if you don't know what you are doing. Some people know enough to create one and so can do it correctly. 

I wouldn't recommend it in general though - piotr and company seem to be exceptions

Would it be best to just try and memorize your wallet mnemonic?

Most likely, yes.  And the dictionary is chosen to make it easier to avoid confusion.

Pls dont use it. There few projects publically open on github that do high performance blockchain parse and dictionary hashing with millions combinations a second on proper hardware. People run them constantly and even in competition with each other.

If you use a brainwallet, be sure to use some non-standard characters:

http://www.motelmaya.com/_BrainWallet.html