Big-brain self-custody solutions?

[virginorange]

Can you split your secret (You own Bitcoin, your 24 words, passphrase, and hidden locations) in such a way, that nobody knows your secret, but they will still tell you, if you forget?

Sounds impossible?

▼ Find out below how to do it ▼


You would like to self-custody your Bitcoin.

Why?
❶ No bankruptcy risk: You want to avoid losing your life savings to a bankruptcy like FTX or Blockfi
❷ Less risk of being robbed: Having your name, your address, your passport and your wealth in a centralized data base is risky. The database could be hacked, and you and your family could be robbed.

Your task:
❶ Don't forget / lose your seed words
❷ Prevent others from gaining access to your seed words.
Best case: You have my seed words stored in multiple safe locations

Your building blocks:
❶ people (family, friends)
❷ stuff (paper, metal plates, Tails OS, USB, Veracrypt, HW-Wallet)
❸ locations


❶ Variant I (the stupid plan)
  ➀ setup:
    ⓐ your house -> here you store your HW-Wallet
    ⓑ your brain -> here you store the PIN for your HW-Wallet
  ➁ access:
    ⓐ You need your brain (PIN) AND your house AND your HW-Wallet to access your Bitcoin
  ➂ how to lose your Bitcoin?
    ⓐ HW-Wallet broken
    ⓑ lose access to your house
    ⓒ forget your PIN
    ▶ main weakness: You lose your Bitcoin, when you forget your PIN or your HW-Wallet breaks, both of wich is likely to happen someday into the future.
  ④ how to get robbed?
    ⓐ robbers enters your house while you are inside and threatens violence
  ⑤ additional advise:
    ⓐ don't use Ledger + Ledgerlive (combination of shipping data and XPUB in a centralized data base), better use Sparrow Wallet (plus I like Coldcard)
    ⓑ encrypt your hard drives (with e.g. Veracrypt)
    ⓒ use Linux instead of Windows and TOR instead of clearnet for better privacy
    ⓓ don't ship the HW-Wallet to your own home address

❷ Variant II (the minimal plan)
  ➀ setup:
    ⓐ your house
      -> HW-Wallet
      -> hidden paper with 24 seed words
    ⓑ your brain
      -> PIN for my HW-Wallet
      -> location of hidden paper
  ➁ access:
    ⓐ brain (PIN) AND house AND HW-Wallet
    ⓑ brain (location of paper) AND house AND paper
  ➂ how to lose your Bitcoin?
    ⓐ lose access to your house
    ⓑ HW-Wallet and Paper are broken
    ⓒ forget PIN AND location of paper
    ▶ main weakness: losing access to your house (surprising divorce, covid quarantine camp, internment camp)
  ④ how to get robbed?
    ⓐ robbers enters your house while you are inside and threatens violence
    ⓑ burglar finds paper (unlikely)
  ⑤ additional advice:
    ⓐ write 24 seed words with pencil on paper, surround paper with transparent duct tape, hide paper well
    ⓑ instead of using your house, you can use 4 other locations (work office, garden house, relative's house, friend's house)
      split your seed words via XOR into two parts (2x), make 2 copies each (2x2=4) and then hide them well

❸ Variant III (the brain plan)
  ➀ setup:
    ⓐ your house
      -> HW-Wallet
      -> hidden paper with 24 seed words
    ⓑ your brain
      -> PIN for your HW-Wallet
      -> location of hidden paper
      -> 24 seed words
  ➁ access:
    ⓐ remember 24 words
    ⓑ have access to your house AND remember the location of the paper AND the paper ist still readable
    ⓒ have access to your house AND remember the PIN for the HW-Wallet AND the HW-Wallet is functional
  ➂ how to lose your Bitcoin?
    ⓐ lose memory completely (PIN and location of paper and 24 words)
    ⓑ lose memory (24 words) AND lost access to house
    ⓒ lose memory (24 words AND pin) AND paper
    ⓓ lose memory (24 words AND location of paper) AND HW-Wallet broken
    ⓔ lose memory (24 words) AND HW-Wallet broken AND paper broken
    ▶ main weakness: your brain stops working (dying, loosing full memory via stroke or accident)
  ④ how to get robbed?
    ⓐ robbers enters your house while you are inside and threatens violence
    ⓑ burglar finds paper (unlikely)
    ⓒ kidnapper kidnaps and tortures you
    ▶ main weakness: if a criminal catches you, you lose everything
  ⑤ additional advice:
    ⓐ memorize the 24 seed words by making up stories or connecting words to locations
   
❹ Variant IV (the decoy)
  ➀ setup:
    ⓐ your house
      -> HW-Wallet
      -> hidden paper with 24 seed words plus passphrase (=25th word)
    ⓑ your brain
      -> PIN for my HW-Wallet
      -> location of hidden paper
      -> 24 seed words plus passphrase
  ➁ access:
    ⓐ remember 24 words plus passphrase
    ⓑ have access to your house AND remember the location of the paper AND the paper ist still readable
    ⓒ have access to your house AND remember the PIN for the HW-Wallet AND the HW-Wallet is functional
  ➂ how to lose your Bitcoin?
    ⓐ lose memory completely (PIN and location of paper and 25 words)
    ⓑ lose memory (25 words) AND lost access to house
    ⓒ lose memory (25 words AND pin) AND paper
    ⓓ lose memory (25 words AND location of paper) AND HW-Wallet broken
    ⓔ lose memory (25 words) AND HW-Wallet broken AND paper broken
    ▶ main weakness: your brain stops working (dying, loosing full memory via stroke or accident)
  ④ how to get robbed?
    ⓐ robbers enters your house while you are inside and threatens violence
    ⓑ burglar finds paper (unlikely)
    ⓒ kidnapper kidnaps and tortures you
    ▶ a criminal might only get part of your savings, if you are lucky
  ⑤ additional advise:
    ⓐ 24 seed words lead to a wallet with a minority of your wealth, 24 seed words plus 25th word lead to a majority of your savings


❺ Variant V (surprised heirs)
  ➀ setup:
    ⓐ your house
      -> HW-Wallet (with 24 words)

      -> Paper "This paper is important, don't throw away! The password for the encrypted USB is PASSWORD2" in the physical paper-based banking folder
      -> Paper "This paper is important, don't throw away! The password for the encrypted USB is PASSWORD2" in the physical paper based important documents folder
      -> Paper "This paper is important, don't throw away! The password for the encrypted USB is PASSWORD2" in several other places your hairs will certainly discover after your death

      -> 6 hidden places in your house with 12 of 24 seed words each
      -> 2 hidden places with your 25th word
      -> 2 hidden places with your 25th word version 2

      -> 2 hidden places with gold

    ⓑ your best friend's house
      -> industrial grade USB-stick encrypted by PASSWORD1 via VeraCrypt containing banking, taxation and real estate documents.
         The USB stick also contains a hidden VeraCrypt partition encrypted by PASSWORD2 containing as text document.
         The text document describes, where all seed phrase parts are hidden. Where your gold is hidden. How to sell it.
         It also contains the sparrow wallet files.
      -> Paper "Please give me back my USB stick, if I lose my memory. Please give this USB-stick to my son, if I die. Please give me back my USB-stick when I ask you for it.
         Before you give back the USB stick, please wait 7 days.

    ⓒ your best friend's memory
      -> Tell your best friend: "I have all my important documents at home. In case of fire or burglary I might lose them all. I would like to store a USB stick with you
         containing an encrypted copy containing banking, taxation and real estate documents.

   store copies of ⓑ and ⓒ with (i) your parents and (ii) your brother

    ⓓ your brain
      -> PIN for your HW-Wallet
      -> location of hidden paper
      -> 24 seed words plus passphrase

  ➁ access:
    ⓐ lose memory or die -> check home office -> check folders -> check banking folder -> find PASSWORD2
      lose memory or die -> check home office -> check folders -> check government document folder -> find PASSWORD2
      receive a bunch of encrypted USB sticks from your friend, your dad, your brother
    -> instead use a number of locations not immediately accessible to you like family, friends, job, bank safe etc.
    -> since the passphrase doesn't show you have bitcoin, you don't have to hide it a lot (e.g. a word on the back of a photograph hanging form your parent's wall).
    -> instead use a number of locations not immediately accessible to you like family, friends, job, bank safe etc.
    -> since the passphrase doesn't show you have bitcoin, you don't have to hide it a lot (e.g. a word on the back of a photograph hanging form your parent's wall).
      open USB stick, decrypt with PASSWORD2, find the location of all your private key parts
    ⓑ have access to your house AND remember the location of the paper AND the paper is still readable
    ⓒ have access to your house AND remember the PIN for the HW-Wallet AND the HW-Wallet is functional
    ⓓ remember 24 words plus passphrase
  ➂ how to lose your Bitcoin?
    ⓐ lose memory completely (PIN and location of paper and 25 words) AND don't find any of the papers containing PASSWORD2
    ⓑ lose memory completely (PIN and location of paper and 25 words) AND don't receive any working USB sticks
    ▶ main weakness: only works if your wife or son is smart
  ④ how to get robbed?
    ⓐ robbers enters your house while you are inside and threatens violence
    ⓑ burglar finds paper (unlikely)
    ⓒ kidnapper kidnaps and tortures you
    ▶ a criminal might only get part of your savings, if you are lucky
  ⑤ additional advise:
    ⓐ You have to build redundancy. Serval Papers with PASSWORD2. Several people with several USB sticks.
    ⓑ Optional: pay a service or rent a virtual private server to send an message to your wife after your death containing PASSWORD2 or the encrypted document with the hidden locations.
    ⓒ Regularly check if the USB sticks still working


❻ Variant VI (kidnapping protection)
  ➀ setup:
    similar to Variant V, with the following differences:
    -> neither store 25th Word in your house nor in your brain
    -> instead use a number of locations not immediately accessible to you like family, friends, job, bank safe etc.
    -> since the passphrase doesn't show you have bitcoin, you don't have to hide it a lot (e.g. a word on the back of a photograph hanging form your parent's wall).

Extension:
Not only hide the 24 Bitcoin seed words, but also your Monero seed words as well as your master password for your password manager


▶ Do you have any improvements for this self-custody plan (Variant V and VI)? ◀  

[1715442758]

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[1715442758]

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[1715442758]

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[franky1]

simpler solutions

trying to explain to burglars 'its a complicated process' will just make them hold onto you for longer unless you give up the convoluted method. usually more threats and beatings would occur until you give in. they dont like to leave empty handed(EG burglary turns into hostage deal)

so

split funds 95%-5%
if threatened give them your 5%, say its all you have

for the 95% funds
use multisig. requiring a couple keypairs. where paper backups are in different locations

trying to make it convoluted where by a burglar gets nothing just makes the burglar threaten harder and get more angry.

better to just give him a little something, for a higher chance he leaves, with you unharmed

[virginorange]

split funds 95%-5%
if threatened give them your 5%, say its all you have

❹ Variant IV (the decoy)
...
ⓐ 24 seed words lead to a wallet with a minority of your wealth, 24 seed words plus 25th word lead to a majority of your savings

I agree with you. It is basically the decoy strategy used by Variant IV, V, and VI.

I definitely don't plan to share my complicated process with a burglar.

use multisig. requiring a couple keypairs. where paper backups are in different locations

❷ Variant II (the minimal plan)
...need
    ⓑ instead of using your house, you can use 4 other locations (work office, garden house, relative's house, friend's house)
      split your seed words via XOR into two parts (2x), make 2 copies each (2x2=4) and then hide them well

Multisig is also a good method splitting your private key into multiple parts. I like the split 24 words plus passphrase, because the passphrase is not recognizable to be part of a Bitcoin wallet and therefore requires less hiding.

A multisig alone also does not solve the inheritance problem. If you hide all pieces of your multisig well, your heirs can't access your bitcoin. If you share the pieces among them, they know you have Bitcoin and additionally could take your money against your wishes.

"❺ Variant V (surprised heirs)" makes it possible to hide your secret from others while also greatly reducing the risk losing your wallet in case of brain damage / memory loss.

[Welsh]

Simplicity is usually the key, to actually remembering things. The more complex you make it, your security actually goes down as a result, due to the fact you'll start forgetting your own process eventually. Simply letting someone know that you trust, that if memory loss occurs they can remind you or show you what you had. However, that really is down to who you trust. I do feel most people have someone they can trust though. Usually, for a lot of people it's a partner.

The only issue with that is your trusting someone who's close enough to you, and could potentially be a part of the accident that might cause memory loss. There's a reason why the royals around the world fly their children separate to their parents, same as driving to various locations. You probably need two people you can trust to be quite confident that if you did lose your memory for whatever reason, they'd be able to help.

However, the more people you trust, the more risk involved.

[Plaguedeath]

It looks really complicated and brain wallet isn't safe because there's a risk where your might suffer brain injury when you're accidentally crash during driving or getting older. Here's the statistic where brain injury has higher chance could happen. You can teach your kids or someone you loved to access your wallet, but if the steps are really complicated, they might also forgot it due to multiple reasons of human error.

Other answers above have told you just how insecure brain wallets are and how humans are a terrible source of entropy. Now, even if you were to generate a properly secure BIP39 seed phrase, here is why you should write it down and not try to remember it.

Each year:

69 million traumatic brain injuries: https://pubmed.ncbi.nlm.nih.gov/29701556/
12 million strokes: https://www.world-stroke.org/assets/downloads/WSO_Global_Stroke_Fact_Sheet.pdf
10 million new diagnoses of dementia: https://www.who.int/news-room/fact-sheets/detail/dementia
5 million new diagnoses of epilepsy: https://www.who.int/news-room/fact-sheets/detail/epilepsy
2.5 million cases of meningitis: https://www.path.org/articles/toward-world-without-meningitis/
2 million new brain tumors: https://academic.oup.com/noa/article/3/1/vdaa178/6043315
1.5 million cases of encephalitis: https://www.sciencedirect.com/science/article/pii/S0163445322002110

[PrivacyG]

It looks really complicated and brain wallet isn't safe because there's a risk where your might suffer brain injury when you're accidentally crash during driving or getting older.

Actually.  I think Brain Wallets are not safe because they are so much easier to crack.  There was a time using Brain Wallets was a thing and some were able to crack thousands of used Wallets in days because people were using Wallets that were not strong enough.  Our minds are not very good when it comes to creating random strings of characters.  So we implicitly create not so strong passwords and Wallets for ourselves.

-
Regards,
PrivacyG

[virginorange]

Our minds are not very good when it comes to creating random strings of characters.  So we implicitly create not so strong passwords and Wallets for ourselves.

I would use either the private key generator of my hardware wallet or dice. So entropy should not be the issue. Variants III to VI use the brain for memorizing the seed words.

It looks really complicated and brain wallet isn't safe because there's a risk where your might suffer brain injury when you're accidentally crash during driving or getting older. Here's the statistic where brain injury has higher chance could happen. You can teach your kids or someone you loved to access your wallet, but if the steps are really complicated, they might also forgot it due to multiple reasons of human error.

I am aware I can forget the seed words. Therefore in each variant II to VI the seed words are written down and hidden.

If you forget your seed words and the location of the written down seed words you can still ask your friend to give you back the USB stick with the manual. Unlock the USB stick and learn that you own Bitcoin and the location of the 24 words.

If you die, your wife will probably worry about money. She will probably check the banking folder. For your funeral she will also check the government documents folder. So she knows that the USB is encrypted with Veracrypt and she knows the password. Since your dad, your brother and your best friend learn you died, they will give the encrypted USB sticks to your wife. So now she has the password and the USB sticks. After decryption she will find one document. She will read the document and learn (i) you own Bitcoin (ii) Bitcoin is valuable (iii) you can sell Bitcoin (iv) you need 24 words + passphrase to use your bitcoin and (v) the location of the words in our house.

I think a reasonably intelligent person is able to install veracrypt and enter a password to unlock the USB. I also think having 24 words plus passphrase makes it reasonably easy to control the Bitcoin wallet.

[franky1]

I definitely don't plan to share my complicated process with a burglar.

the thing about having one seed which you have to bring together by you travelling to different locations is.. well
once you gathered it once. you dont need to gather the word again. because they are then in the one location..

oh and if a clever burglar knows your addresses. and watches that once a week you were to go to different locations to get each word of 'xor' split and then come home to link them. he just has to wait for you to "come home"

where as..
using multisig
you can prepare a raw tx at home(unsigned).. and then when going to different locations. get the signature from each location. and then broadcast it.
whereby the keys stay at the locations and just sign at each location..
which is much more secure. and also means your not bringing the keys home where a burglar is waiting

"one seed split" means bringing seed together to then sign in one device. thus compromising the device by holding the combined seed thus no longer needing multiple locations there after

"multisig" means keys stay separate, they take in raw tx and give out signature at each location. where you are only taking the signatures with you. not the keys.

[virginorange]

Simplicity is usually the key, to actually remembering things. The more complex you make it, your security actually goes down as a result, due to the fact you'll start forgetting your own process eventually.

Fully agree.

However there is a difference between building and using.

The building part is complicated, which I only have to do once. Later I can forget everything.

For using:
use hw-wallet, enter pin, sign transaction.
if hw-wallet broken, recover paper words to recover wallet
if paper words location forgotten, check banking folder and ask friend for usb stick

[virginorange]

watches that once a week you were to go to different locations to get each word of 'xor' split and hen come home to link them. he just has to wait for you to "come home"

If you lead an exchange or a DAO, with high Bitcoin amount and high turnover, multisig is the way to go. Other people already know you do "something with Bitcoin".

A guy, who saves into Bitcoin, would combine the XOR-seeds or 24 words + passphrase less than once a year, since he mostly only accumulates into a watch only wallet.

A multisig setup (at least 2 of 3, better 3 of 5) requires at least 3 locations, which can hold a hardware wallet plus 24 seed words on paper. Sounds difficult to hide. Many people don't control so many locations well enough.

Hiding 24 words on paper is much easier (small, not metal). Hiding a passphrase is even easier, since nobody even knows the passphrase belongs to a wallet.

• Let's say you own 20 books at the doctor's office you work at. Book 4 on page 263 has a passphrase. You have some written note books from the years 2013-2023. In the note book from 2015 on page 22.11.2015 there is a passphrase. A passphrase doesn't even have to be locked or hidden. It is just a paper among papers, a note among notes.
  
• Let's say you have 500 pictures of your kids. One of the digital pictures has a hidden stenographic message. You have 10 photo books. the photos have descriptions. One of the descriptions contains your paraphrase. Between the pictures and the book there are some seed words.

Words can be hidden anywhere. Hardwarewallets and laptops not.

I still keep an open mind about multisig. Maybe I miss some information. But with my current knowledge and my low frequency sending of funds, I prefer 24W+25th word or seed splitting with XOR.

[tbct_mt2]

Do you think you are complicate things too much?

The more complexity you try to do, the higher risk you will lose your bitcoins.

No guarantee that along the procedure (that is complex than necessary by your personal set-up), if one chain in the procedure is broken, you lose your bitcoins.

Multi-signature wallet and good security, good backups are good enough for main of your capital.

For your small capital that you need to bring it around the corner to spend for coffee, books, shopping, let's use single signature wallet and maybe on your mobile too. Also remember to have its backup.

[virginorange]

Do you think you are complicate things too much?

Depends if the ways to access your Bitcoin are connected via AND or OR

Scenario 1:
to get your Bitcoin you have to do (a) AND (b)

Scenario 2:
to get your Bitcoin you have to do (a) AND (b) AND (c)
▶ more difficult to set up, since you also need to set up (c)
▶ more risky to lose your Bitcoin, since one more piece can break

Scenario 3:
to get your Bitcoin you can do:
(a) AND (b) OR
(c) AND (d) OR
(f) AND (g)
▶ much more difficult to set up, since you have to set up many pieces (a) to (g)
▶ very safe, since now you have 3 ways instead of one way to recover your Bitcoin

[o_e_l_e_o]

Depends if the ways to access your Bitcoin are connected via AND or OR

It is always a balance between security, risk, and convenience.

If you set up a system which only requires access to (a), then you can duplicate (a) across multiple sites and mediums, meaning it will be very resistant to accidental loss. However, it will be poorly resistant to theft, since an attacker only has to recover one of your several back ups in order to access your wallet.

Conversely, a system which requires access to (a) AND (b) AND (c) is very resistant to theft, but poorly resistant to loss. You can make it more resistant to loss by having two or even three copies of each part, but then that becomes more and more inconvenient to find different secure places to store 6 or even 9 separate pieces of your back up.

A few general comments about your various proposals: First, your memory is never safe and never reliable, for the reasons in my post Plaguedeath has quoted above. You should never rely on memorizing your seed phrase. Secondly, any system where all your back ups are stored in the same location as your wallets themselves (such as having both your hardware device and your paper back ups all stored in your house) is very poorly resistant to loss, since a single accident, natural event, fire, etc., can destroy both. You need offsite back up.