This is a valid point. While I do know, that human beings are bad at creating randomness, we tolerate this weakness for practical purposes: Or don't you have passwords you chose by yourself? But the longer your self-chosen password / passphrase gets, the more it compensates the weaknesses of its non-randomness. Thats why I came up with the last question in my OP: "How many words do you think you have to collect with this method to meet standard-brain-wallet-security?"

I will have a closer look at alternative clients and they will have a place in my bitcoin-environment. But software-solutions don't qualify for my "total-foolproofness"-standards.

Cool! I never heard of that! This is definitely a good idea if you want to give your bitcoin-credentials to friends.

Thank you for commenting, davidgdg

Reading your answer I think I have to explain in more detail the "use case"/ the scenario I have in mind for this method.

Let's say, it is intended to be a foolproof method for bitcoin cold-storage: I bought a bunch of bitcoins in the last months. It might be the case, that I loose interest in following bitcoin-news the next years (checking exchange-rates, legal status, security measures, new applications... whatever). So if in 5 years I discover that bitcoin is a huge thing then and my bitcoins are worth a fortune, i want to be able to redeem them. So, yes, the two problems you mentioned are exactly the problem, but your requirement is not exactly the one I have in mind:
I want to have a method where I do not have to remember any information at all (well, at least, not any new information. I only use information I already know since my childhood). Using this information I do not have to remember, that the privateKey/passphrase is hidden in clown.jpg (which additionally might get lost in a HD-Crash) or in grannys birthday letter (which might get lost also). I can write the whole process on a piece of paper that I can put in my "finance"-folder on the shelf. And I can even give a copy of that paper to a good friend. Restoring the passphrase from the cloze text is easy for me but impossible for anyone else.

Both answers you give here do require either remembering at least some new information (you have to be able to recall it in 5 years) or you have to make sure that nobody else gets to see your paper-wallet.

Sorry, but I think the point Abdussamad (and to a lesser extend MPOE-PR) is trying to make is, that "security by obscurity" is a bad idea. While this is true, I don't think that the suggested method is such a "security by obscurity"-idea.
You can put the whole process described above on a piece of paper together with your cloze-text.

It has about the same drawbacks like a brainwallet though: If you get a stroke or if you die - the BTCs are gone.

Thanks for taking your time on commenting!

The usual method for BTC-cold-storage is well known (Generate key-pairs with the bitaddress-page on an offline computer and so on. Details here for exampe...)

Problem: Paper Wallets have to be printed out. And to be secure you should store them at different places. And there goes the security... Maybe someone manages to take a photo of the address-pairs and you're f***ed.
Brain Wallets can fix this, but you have to choose very long passphrases. And if you are not recalling your passphrase from time to time, you will forget it (Don't overestimate your powers...).

Solution: So I'd like to suggest a method that fixes both of the aforementioned problems:

Pick sentences from your favourite childrens book or from your favourite poems, lets say:

Quoth the raven, “Nevermore.”
Bob the builder: Can we fix it? Yes we can
... and so forth.

The above (incomplete) method yields the passphrase

ravennevermorebuilderfixwe

You now can write on a piece of paper as your memorizing-aid:
Quoth the -, “-.”
Bob the -: Can we - it? Yes - can

To apply this method correctly, you obviously shouldnt choose phrases like those above as they are too easy. Anyone knows them. But when I flip the pages of my favourite children books (or poems, or things my mom said to me that stuck or....) I always stumble upon everyday-sentences, that have no importance to anyone but me: For me they were (for whatever reason) highly memorable. You can write down the sentences, by replacing the relevant passphrase-words with a dash. Ideally not even your close family members are capable of filling these dashes with the right words. So you can write down these clozes, which is for you like a perfect reminder, but useless for anyone else.

Advantages: You can produce very lengthy passphrases you do not need to memorize, as you can write them down without giving too many hints to others (ideally)

Disadvantages: Close to random choice of words, but not perfectly random.

Question: How many words do you think you have to collect with this method to meet standard-brain-wallet-security?

Hello everyone,

I am not so new with bitcoin anymore (I already invested a small percentage of my savings in bitcoin, created my paper-wallets on an offline machine with bitaddress.org to store them etc. etc.) but I am still new to bitcointalk.org, as I haven't posted anything yet.

This post is just here to get rid of my bitcointalk-newbie-status, because I'd like to discuss an idea in another appropriate subforum. Three good friends of mine are going to visit me tomorrow and they're interested in bitcoin. And instead of just explaining the basics to them, I'd like to play through all the fundamental concepts of bitcoin on paper: Having them creating their own key-pairs, having a piece of paper on the table with all transactions (aka the blockchain) and so on. This is only possible by strongly simplifying the whole thing. I have some ideas how to do this, and I'd like to discuss them.

Thanks for your patience - zaubertrank