Topic: Shamir backup sounds dumb to me (Read 286 times)

Very random thought.  Shamir Backups are very good for somebody who owns multiple properties.  Or has one property and knows they can have access to the house of their parents at any given time too.  Or, if you have a garden then it may be very useful to bury it in very different spots in case a thief some how gains access to one of them.

Other wise, I would strongly advise everybody who adopts this Backup method to consider the possibility of significant changes in relationships.  Imagine you and three more people are best friends and two of your friends hang out and die.  Would their family really give you access to their house?  Why would you put ANY Trust in them?

Trust only yourself as much as you can.  Do not place your Trust in others.  It can be breached and broken any time.

You don't need to trust or keep the secret parts of Shamir with some people, you can leave them hidden somewhere, for example, your home, work or the home of friends or relatives (or close to them).

The Shamir backup method, as innovative as it may be, is still not a use case for me. If the purpose is to protect yourself from thieves, it would be better to find a solution based on passphrases that offer plausible deniability, such as BIP85.

Or you can split your seed words and place them in multiple locations.
There is nothing strange about that, it is similar to multisig setup that exists for a long time, but with shamir secret sharing you are doing it without online transactions.

Even if one of the shares is lost you can still recover you keys, depending how many shares you created.
Shamir Secret Sharing or SLIP39 is not for everyone, but it makes your seed words more secure than using just a regular backup.
I suggest readin more about it on trezor website:
https://content.trezor.io/slip39

No, he was actually talking about dumb seed splitting, and he recommended it is better to use Shamir Secert Sharing (SLIP39).

If the person who keeps one piece of your wallet mnemonic seed was not informed importance of it, he will more likely to be careless with it. It increases risk of losing that piece of your wallet backup.

In general, seed splitting is very bad idea, even the method used is Shamir's Secret Sharing.

Why is Seed Splitting a Bad Idea? It's a video explains on Shamir's Secret Sharing that is risky and bad idea for your wallet backup.

Well if you are afraid of that, you can encrypt or encode the shares with a system or a key you will keep with you, or you will give to another person without saying what it is. AFAIK SLIP39 allows you to use a passphrase by the way. Unfortunately, if you lose it or the person you've given that lose it himself you won't be able to recover your seed even if your friends give you back their shares.

You are right to question Shamir backup safety. It divides your recovery code among trusted people but this creates problems. You have to trust others with sensitive info which goes against Bitcoin idea of independence. There are four main issues trusting others and human mistakes like losing or throwing away code parts and others not understanding crypto. It is good to keep control yourself. You should use other backup options like secure hardware wallets or personal note storage. These methods keep you secure and reduce depending on others aligning with crypto core principle of self protection and caution when sharing sensitive information.

This is the first time I'm hearing of this as a term.
Aside from the fact that they can misplace their part of the phrase, it's a very safe way to secure your seed phases. If it's possible that each person holding each part of the seed phrase won't know the other holders, then it's safer, but as you said, they can misplace it. If it can be certain that they won't misplace it and they don't know others who have other parts of the seed phrase then it's a very safe way to keep your seed phrase.


In this context, bitcoin is not against third parties. I mean, there's nothing wrong with keeping your seed phrase in a safe deposit box, is there? That's a third party. There's no written or unwritten rule that says you have to be the one to keep your seed phrase.
If the safest and most secure way for you to keep your seed phrase is with your mother or father because of how much you trust them and how careful and thorough they are then go ahead. I don't think there's anything wrong with that.

You don't have to use Trezor for recovering your wallet from shamir backup. Electrum supports shamir backup too.
To import shamir shares in electrum, click "options" on "Enter Seed" window and select "SLIP39 seed".

I read shamir backup is relying on dependent, so if you use Trezor to generate it, you need have the Trezor in order to access your coins. While in multisig, you don't have to worry if you lost your Trezor, you can still able to access it as long as you have the signatures. https://www.reddit.com/r/TREZOR/comments/1d2yp6r/comment/l650upi/

For me it's not safe to use shamir backup.

I would say seed phrase + passphrase is safer, you can give your seed phrase to criminal when you're under attack or hacker drain your wallet, but the main one (seed phrase + passphrase) is still safe.

I've never heard anything about this Shamir backup. It sounds really dumb. Sharing parts of a key phrase with several people is pointless.
The only way to keep your seed phrase is you to write it down on a piece of paper and keep it somewhere safe. The whole point of Bitcoin/crypto is to never trust anyone, but yourself. No friends and family. No companies and third parties. Trust only yourself and be your own bank.

This is my first time hearing about this and apparently it is done so that there is no single point of attack or failure. So if one part of your seedphrase it lost or taken, your funds will still stay safe because they never know the whole thing so they can't access it either way. It is quite confusing though. If one person loses a part of your seedphrase then how will you access your funds?

Seems unnecessary to me. I am in support of distributing your back up keys but not to people who are also vulnerable of losing it. At the end of the day, you only should have whole access to any information valuable to you.

Seed spliting for a wallet backup is terrible idea.

Shamir is a method like this, and I dislike it and don't use it for my wallet backup. Some Bitcoin experts warn us about this bad backup method too with many shortcomings in this method.

Shamir's Secret Sharing shortcomings.
Bitcoin Q&A: Why is Seed Splitting a Bad Idea?

If you want to back up your wallet rightly, read
How to back up a seed phrase?

My biggest issue with Shamir Backups is that I do not Trust people and I would NEVER feel safe if anybody had a piece of my Seed, even if I knew they could not steal my Bitcoin with that one piece alone.

The friends I have most Trust in know each other.  And I think it is hard not to have close friends you Trust the most who know each other because I at least typically spend time in the same environment as they do.  This means they could at any given time plan to screw me up and secretly share their pieces of my Seed.

I have had so many coincidences happen in this life time to think this would ever be safe.  I rather put my Seed somewhere and find it vanished than know I put pieces of my Seed in the hands of somebody else and Trust I would some day get it back.  What if they say no?  What if they go crazy mentally?  What if they die and their family does not want to interact with me?  There are so many variables that I would rather simply not.

You don't have to find several people if you don't want to. Shamir lets you to create multiple backups, it's up to you how you'll use them. You can create 2, 3 or more backups and save them yourself in one, two, three places or wherever you want and however you want.

Shamir backup is not the best strategy, everything is individual. It might be best solution for you, worst solution for others but it's 100% guaranteed that if you keep your shares in the same place, it loses its whole meaning and value, i.e. now you have a single point of failure and there is no point in having 2 or more backups. The whole point of Shamir backup is to avoid that issue and save them in a way that in emergency case, for example, 2 out of 3 will be available.
It's up to you where and how you'll save them and it's better to not talk about that details but you can find many creative ideas.

As already explained in previous comments, Shamir secret sharing lets you do more than you thought.  You should read up on it a bit more to see what I mean.  The main thing is, you dont have to keep all the shares for yourself.  Think about this - say you keep them all, and somehow you lose them. Its done deal, secrets gone.   

There is no perfect backup method. Each has its own advantages and disadvantages. The whole purpose of this Shamir scheme is spreading out the risk.  Keep some shares for yourself give a couple to people you trust like friends or family, maybe stick a few in a safe place somewhere.  That way, even if you lose one or two shares or someone gets their hands on them, you can still get your secret back.

You shouldn't forget the main point of the Shamir's Secret Sharing Scheme, you don't need ALL the shares generated to get back your seed or your private key, you can choose and set up to only need 2 parts among a total of 5 different shares to get back your secret for example, hence even if 3 shares are missing, you will able to get back your seed. In addition, you can rather easily find on internet objects or systems, allowing to hide USB sticks, documents, money, jewels or other precious things. So your seedphrase will only be lost, if the object is thrown away.

You've missed the part that the "parts" are overlapping, so you always need a smaller number than all (eg 2 of 3) to get your coins.

Plus, it's not that you have to give it to people. For example it's advised to keep your seed phrase in multiple places, geographically separated (so in case of war or natural catastrophe you're still good). While doing this with the full seed is a risk, you can do this with parts of SSS. It can be in safe, it can be at somebody you know, it can be buried underground or hidden in walls, it doesn't matter. The point is to avoid the risk that if one of the backups is getting onto wrong hands, you are not screwed (which can happen when you backup full seed).

As said, SSS has pluses and minuses. Maybe other 2-3 people you give the backups can team up against you, for example. However, you can also use it smart, for your benefit. I am not super pro or anti SSS; I leave it up to you. But it's certainly not "dumb".

I believe that I've heard something related to Shamir, before now, but I'm getting the full meaning of how it functions in this thread. Like you i won't recommend it either, I'd rather hide my seed phrase in different locations by myself, instead of putting it in the custody of others. True decentralization is about having total control of your keys, that is the essence of the freedom over your coins. What if the people that you entrusted with your keys loses it or decides to connive and steal your coins? The Shamir option is ok if the individuals can be trusted but it's better to hide the keys in different locations by yourself.

No, that's not how a shamir Backup should be used. You should keep all the shares by yourself. You create a SLIP39 seed phrase, so that a single seed phrase is not enough for a thief.
If you want to have a wallet in which transactions are authorized by multiple people, go for a multi-signature wallet.


Take note that if you have a shamir backup, there are still 1 signature required for any transaction you make.
When you create a m of n multi-signature wallet, there are m signatures required for making transactions.

Well if you keep all the shares yourself that may be a better way to do it. Just distribute shares in a bunch of different places.
Then you could avoid having a single point of failure where you have the whole key in one place and it gets lost or forgotten, or stolen.

Although I really haven't heard of this method of seed storage, I think from what the OP is explaining it is different from how the regular multi sig wallets work. From the name, multi Sig wallets literally split the signature, meaning both Parties would have to sign a transaction from that wallet for it to be valid and have a transaction hash.

Anyways with that being said, I really don't fancy the idea of splitting your seed phrase into different pieces and storing them in different places. Well  one of my reasons is because say you split  a 12 word seed into 4 places then you end up losing one piece to probably naturally disaster, you would  then need to go through a stressful recovery process to brute force what you have left.
I think duplicating and storing in safe places is a better option.

Assuming it is 2-of-3 multisig. If the wallet has been setup already, only 2 keys are required for making transactions. But if you want to recover the wallet, you will need the 3 keys.

Not necessarily all the backups. I explained that above. It depends on the number of sheets that you set when you generate the shares. You can generate 5 shares and only set it to require 3 for the recovery.

Yes Shamir backup is similar to multisig. But with multisig I believe you need two or more of the keys to execute any transactions, or just sending transactions.
But with Shamir you only need the backup keys to restore your wallet, ie: your hardware wallet becomes lost, stolen or destroyed.

You can keep the backups yourself.

Assuming you generate 3 shares for it, you can set it in a way that only 2 is required for the recovery. You can even make it 1 for the recovery but no purpose of having 3 shares in this regard. I just use it to explain.

You can keep all the shares yourself. But it can help just like multisig but it is different from multisig.

Reputed members on this forum like gmaxwell does not recommend it.

SSS has pros and cons, One of its advantages is that it is safer than using a single wallet seed. In the case of the seed, if someone can access it, they will get your money, while in SSS, they may need 2 thresholds out of3 shares.
But in any case, the multi-sig wallet is better and gives you multiple options according to what you want.
There are many detailed discussions here:

 - https://bitcointalksearch.org/topic/m.62893823
 - https://bitcointalksearch.org/topic/m.61545852
 - https://bitcointalksearch.org/topic/m.56726302

I haven't heard of this before, sounds similar to mulitsig but then sharing your seed with others in piece?.. well I won't recommend it though.. as a someone who really want to enjoy the freedom of a decentralized system and being your own bank.. it's best to keep your keys your self. I don't see how difficult it is to store your seed offline and in a place where only you will be aware of..

Let me see if I understand this correctly of how Shamir backup works.
So you have to find several people you trust, and each one is supposed to hold a part of your backup key or seedphrase?

Even if you trust each of these people, how do you know one or more of them won't accidentally lose it or forget about it and throw it away? Then you are screwed.
They make it sound so easy to just find a few people who are willing to take on such a major responsibility for you. Bitcoin is supposed to be about avoiding counterparty risk and avoid having to trust third parties. But with Shamir backup you are introducing several third parties into the equation and entrusting them with your life savings.

Yeah sure you can trust your mom or dad, but how can you trust them not to accidentally lose their secret part of the phrase? Which is very easy to do. Especially with older people who tend not to understand crypto at all or usually think of it as a scam and want nothing to do with it. Of course they will want you to explain to them exactly what you are asking them to do, which likely they won't ever understand even after you explain it. They barely understand how to use a computer. It just sounds like a dumb idea to me. When it comes to crypto you can't trust anyone but yourself.