# Gavin Andresen
# 2013-01-27 23:49:08
# https://bitcointalk.org/index.php?topic=139390.msg1484096#msg1484096

Humans are pretty bad at being original. REALLY bad at being random. And we are terrible at comprehending huge numbers. @p{par}

So if you ask the average person to create a secure passphrase, they're very likely to create something that a "determined attacker" with a lot of computing power can crack. @p{par}

I think if people start to use quotes from obscure literary works as their brain wallets, then they're going to lose their bitcoins sooner or later. Attackers can try MILLIONS of passphrases per minute, to crack EVERY SINGLE brainwallet that has ever been created. @p{par}

So: if you absolutely, positively won't be dissuaded from using a brainwallet, here is my advice on how you @p{(it}might@p{it)} be able to come up with a secure passphrase: @p{par}

Think of two passphrases that you think you can remember. And think of a government-issued number that you can easily lookup or remember (like your driving license or social security number). @p{par}

Create a brainwallet passphrase that is: @p{par}

the first passphrase,the government id number,the second passphrase @p{par}

Then create a 'sentinel' brainwallet that is just the first passphrase, and send a small number of bitcoins to it. When those bitcoins get spent (or more bitcoins are sent to it by somebody else), you know that the first passphrase you chose isn't good enough any more.  Choose a more complicated passphrase and create a new 'sentinel' and real brainwallet, and move your old brainwallet there. @p{par}