Hello folks,
I have read a lot about brain wallets. They sure are intriguing in that you would never have to write anything down that could be discovered by someone else. They are also inherently unsafe in that the passphrase can be brute forced, rainbowed, dictionaried, etc. I did a little expedition, and found a number of brain wallets, by trial and error:
1. The Merkle Root hash of the Genesis Block creates a valid address that has been funded in the past
2. The secret message in the Genesis Block "The Times 03/Jan/2009 ....." also creates a valid and funded address
3. Satoshi's name in many variants, mixed case, lower case, including/excluding blanks leads to many brain wallets
4. "Dread Pirate Roberts" leads to a brain wallet
5. "it was the best of times it was the worst of times" leads to a valid brain wallet
6. bitaddress.org has a vanity address 1NiNja1bUmhSoTXozBRBEtR8LeF9TGbZBN - it will lead to a valid brain wallet address
7. "to be or not to be" has a valid address.
There is a good piece on why not to use brain wallets
http://fc16.ifca.ai/preproceedings/36_Vasek.pdfhowever, I can think of ways to improve security and still benefit from the convenience.
1. Create a phrase you are able to remember, for example: "Al Gore invented the Internet and that's an inconvenient truth."
2. Send this through an independent SHA256 generator with a SALT phrase of : "We consume too much NACL."
3. Take the resulting hash as an input for generating your brain wallet address.
Challenge me ;-)
And what purpose does it serves? An additional layer of security/safety? A strong password is a strong password, why load the brain with remembering public and private keys. I have a word document dedicated to copy paste all the different passwords in different sites. I have to be a memory man to get through all these without the doc.
If you are using a weak password you would get hacked one way or the other, if you are using a strong password you are immune to hackers, it's as simple as that.
The only problem you then face is law enforcement or criminals compelling you to give up your passphrase. In this case, you might be able to get away with creating a dummy pass phrase to an address that you already have some bitcoins on. However, due to the block chain, whoever is forcing you to divulge your pass phrase may know you are lying.
http://www.coindesk.com/how-to-create-a-brain-wallet/Bitcoins in one's own mind by memorizing a mnemonic recovery seed. If the mnemonic is not recorded anywhere, the Bitcoins can be thought of as being held only in the mind of the owner. If a brainwallet is forgotten or the person dies or is permanently incapacitated, the Bitcoins are lost forever.
Practically everyone who knows about or cares loudly yells at people DO NOT USE BRAINWALLETS [GENERATED BY HUMANS]. We've seen pretty concrete evidence that users are resistant to good advice in this space, and they are shocked when their favorite quotation is cracked and they lose their coins (But it was 60 characters long! I even added a special character! how is this possible?!), the existing sites promoting this stuff won't use a KDF stronger than SHA256*1 because "users are stupid if they use weak passwords".
https://en.bitcoin.it/wiki/BrainwalletWhy go through all this mind wallet hassle if you have a strong password.