If you are worried about the brute-forcing of sha256 brain wallets, you might want to consider warp wallet (
https://keybase.io/warp). It uses a large number of rounds of scrypt, which makes even a simple 8-char alphanumeric password reasonably strong. For more security, it lets you add a memorable hash (eg your email address).
A simpler wallet backup scheme has a better chance of being actually reliable than a more convoluted one. Whatever you do, make sure you somehow document it in case you forget what you did. Also, leave behind enough information for your heirs so that they can recover your coins in case you become incapacitated.
-- FK
Hi guys,
Im a fan of storing bitcoin in a brain wallet, despite having learned my lesson rather brutally to make a ridiculously strong pass phrase. You can sleep at night knowing that weather your house gets flooded or burns down, or your computer gets hacked or stolen that your bitcoins will be safe. I like to make all my wallets brain wallets and import them into my MultiBit client.
So to make an extra secure passphrase I had an idea....
Take a reasonably good phrase, add some character, but it can be memorable. Generate your private key from that phrase. now take your public key and pass it through the SHA algorithm again. You can do this as many times as you like within reason, as you know you will inevitably find your address with this method if you try one at a time.
Im not sure how much security this method would add (apart from the number of times you rehash you public key) but my thinking is that for a computer to have to process the SHA algorithm for every brain wallet combination out there just a few times will drain plenty enough processing power to be impractical. I like this method because its so simple and easy to remember and you may use a memorable pass phrase within reason.
how much work would this add to the process of testing random brain wallets?
Thanks!