Is It Possible to "Reserve" a Private Key?

[johndebord]

Is it possible to "reserve" a private key? In other words, can someone select a private key and perform an action (such as creating a specific transaction or something else) that effectively claims or reserves that key?

[Findingnemo]

can someone select a private key and perform an action (such as creating a specific transaction or something else) that effectively claims or reserves that key?

There is no need to 'reserve' it.

Once you create a private key, it is completely yours forever unless you expose it to someone else intentionally or unintentionally. There is no possible way that someone can generate the same private key as yours in a life time and FYI you no need to create any transaction to do that, all you need to do is generate a key using the mnemonic seed and generate a corresponding bitcoin address for it.

But don't try to create a private key on your own, the randomness of human genrated generated priv keys is expected to be weak.

[apogio]

Is it possible to "reserve" a private key? In other words, can someone select a private key and perform an action (such as creating a specific transaction or something else) that effectively claims or reserves that key?

Apart from the fact that it's not possible to reserve it, what do you want to achieve?

A private key is the way to sign bitcoin transactions. If there is a private key X and there are 10 people that know it, then whoever uses it first will eventually get the coins.

So, even if you "reserved" the key, even though I don't know what "reserve" means, if anyone got the key they would be able to steal your funds.

The good thing though, is that if you protect your private key correctly, you are guarranteed to be the only one to own it, hence, you can reserve it without doing anything.

[FatFork]

Is it possible to "reserve" a private key? In other words, can someone select a private key and perform an action (such as creating a specific transaction or something else) that effectively claims or reserves that key?

Private keys should be, well, private! You can't reserve something that no one should even know exists, let alone its content. If someone knows your private key, they have control of your funds. Period.

[Saint-loup]

The only thing you can do, or at least the simplest one, is to sign a message with this private key dealing with your identity or things related to your identity and to post the signed message on a public space where messages are dated, like this forum. Then if one day someone steals your funds, or your address(in order to sign messages with it for example) you could have a clue showing the address and the funds onto it belonged to you actually.

[johndebord]

I appreciate the responses and I understand the importance of keeping a private key secure and secret. However, I think my question may not have been fully clear.

To clarify my question: Is there a way to maintain ownership of a private key even when you intend to reveal it to someone else?

For example, let’s say my private key is 0101010101010101010101010101010101010101010101010101010101010101, and I choose to disclose this key to someone else. Given that I'm willingly revealing the private key, is there a method or technique that would allow me to maintain control or ownership over that key and any future funds associated with it? Or is it simply impossible to preserve ownership?

[memehunter]

I appreciate the responses and I understand the importance of keeping a private key secure and secret. However, I think my question may not have been fully clear.

To clarify my question: Is there a way to maintain ownership of a private key even when you intend to reveal it to someone else?

For example, let’s say my private key is 0101010101010101010101010101010101010101010101010101010101010101, and I choose to disclose this key to someone else. Given that I'm willingly revealing the private key, is there a method or technique that would allow me to maintain control or ownership over that key and any future funds associated with it? Or is it simply impossible to preserve ownership?

NO. You must not share your private key with anyone, no matter what. Maybe you've heard the phrase 'Not your keys, not your coins.' There's another one for you: 'I know your keys, now your coins are mine'
Although there is a method to prove the owner ship of a particular wallet (if your looking to provide someone proof of funds etc.) You can prove ownership of cryptocurrencies by signing a message with your private key, which creates a cryptographic proof without revealing the key itself. The signed message can then be verified using the public key to confirm ownership.
You will find some useful information here : https://bitcointalk.org/index.php?topic=990345.msg10775520#msg10775520

[pooya87]

To clarify my question: Is there a way to maintain ownership of a private key even when you intend to reveal it to someone else?

Given that I'm willingly revealing the private key, is there a method or technique that would allow me to maintain control or ownership over that key and any future funds associated with it? Or is it simply impossible to preserve ownership?

This sounds like an XY problem where you need to explain what your objective is for sharing the private key with someone else so that people can help you better.

Otherwise as far as sharing the key goes, you are also sharing the ownership of the funs associated with it and anybody with the key can spend those coins and there is no way to prevent that.

[ElectrumHelpMe]

I appreciate the responses and I understand the importance of keeping a private key secure and secret. However, I think my question may not have been fully clear.

To clarify my question: Is there a way to maintain ownership of a private key even when you intend to reveal it to someone else?

For example, let’s say my private key is 0101010101010101010101010101010101010101010101010101010101010101, and I choose to disclose this key to someone else. Given that I'm willingly revealing the private key, is there a method or technique that would allow me to maintain control or ownership over that key and any future funds associated with it? Or is it simply impossible to preserve ownership?

private key is like your naked pictures...
once someone saw them ... there is no way to unsee them...

so once someone has the key , there is nothing you can do about...
you both have the key, is same key, wont change, the key do same thing , same porpoise , he/you cant do more.

[FatFork]

To clarify my question: Is there a way to maintain ownership of a private key even when you intend to reveal it to someone else?

I suppose you could write a short message and broadcast it to the blockchain, which could serve as proof in the future that you owned that private key at a certain point in time. But I don't see the practical purpose of it.

Think about it logically. If there are funds associated with that private key, and you share it with someone, any party will be able to spend those funds and there is no way to prove who initiated the transaction. In the event of a dispute, it would be your word against theirs. Even if you trust someone completely, you can't guarantee that they won't accidentally reveal your private key to someone else, or that their own security measures will be perfect. In other words, once your private key is out there, there's no way to get it back.

So, to answer your question directly: No. There's no way to maintain ownership of a private key once you share it with someone.

Why would you want to share your private key with others in the first place? Maybe you're asking the wrong questions. There might be a better way to handle your situation.

[Porfirii]

Well, this won't be a popular answer because the belief that "not your keys, not your coins" is almost sacred in our circle. But if we go further and study a little bit of Civil Law, things don't work like that in a court.

Imagine that you share your car keys with a friend. Your friend can disappear with your car, but your car is still yours, you can prove it, and he would be persecuted and forced to return the car to you, or compensate you if it were impossible.

So if you create a private key and you share it with a different person but you have proof that you didn't do that with the intention of detaching you from its property (by signing a message or whatever other means), then your friend can steal your coins, but the legitimate ownership would still be yours and you could perfectly sue your friend.

[Saint-loup]

Well, this won't be a popular answer because the belief that "not your keys, not your coins" is almost sacred in our circle. But if we go further and study a little bit of Civil Law, things don't work like that in a court.

Imagine that you share your car keys with a friend. Your friend can disappear with your car, but your car is still yours, you can prove it, and he would be persecuted and forced to return the car to you, or compensate you if it were impossible.

So if you create a private key and you share it with a different person but you have proof that you didn't do that with the intention of detaching you from its property (by signing a message or whatever other means), then your friend can steal your coins, but the legitimate ownership would still be yours and you could perfectly sue your friend.

Yes I agree with you, it would be the same thing as saying once you've lent something to someone, or you've put it in a public place, an object doesn't belong to you anymore. So you can't leave an umbrella or shoes in front of your door because anybody has the right to take them, and if you lose your wallet in the street the first person finding it becomes its new owner. Fortunately things don't work like that in real wife otherwise the concept of property wouldn't exist anymore. Actually, the owner of an object is assumed to be the one holding and using it... unless proven otherwise.
Keys are not supposed to be shared though, because on chain transactions are here to prove the transfer of ownership of funds, and it's the simplest and the most efficient way to do it. So if for some reasons someone needs to share a Bitcoin address with someone else it's better to use a multisig one IMO, it allows to share the ownership in a more convenient way.

[FatFork]

Well, this won't be a popular answer because the belief that "not your keys, not your coins" is almost sacred in our circle. But if we go further and study a little bit of Civil Law, things don't work like that in a court.

Imagine that you share your car keys with a friend. Your friend can disappear with your car, but your car is still yours, you can prove it, and he would be persecuted and forced to return the car to you, or compensate you if it were impossible.

So if you create a private key and you share it with a different person but you have proof that you didn't do that with the intention of detaching you from its property (by signing a message or whatever other means), then your friend can steal your coins, but the legitimate ownership would still be yours and you could perfectly sue your friend.

Yes I agree with you, it would be the same thing as saying once you've lent something to someone, or you've put it in a public place an object doesn't belong to you anymore. So you can't leave an umbrella or shoes in front of your door because anybody has the right to take them, and if you lose your wallet in the street the first person finding it becomes his new owner. Fortunately things don't work like that in real wife otherwise the concept of property wouldn't exist anymore. Actually, the owner of an object is assumed to be the one holding and using it... unless proven otherwise.

Yes, that's true. The concept of ownership is a strong legal argument in the physical world, even in the digital world. Just like you can prove ownership of a car by showing the registration, you can also prove ownership of cryptocurrency with the private key.

However, there's a key difference between physical property and digital property. Physical property is tangible and can be physically transferred from one person to another. Digital property like private keys, on the other hand, is intangible and can be easily copied or transferred. Therefore, there can be literally unlimited copies of the same. So if we take the car analogy, in the first case we have a physical object that has been stolen and you have strong legal grounds to pursue the perpetrator. While in the second case you can't actually claim that your private key was stolen from you because you actually voluntarily gave away only a copy of it. And as for the assets associated with the key, as I already mentioned in the previous post, it will be difficult (not to say impossible) to prove which copy of the key was used for the transaction. So, legally, you'll have a weak case. Unless of course the thief is stupid enough to send funds to one of the KYC-ed exchanges, or there is some other physical evidence or testimony, etc.

Keys are not supposed to be shared though, because on chain transactions are here to prove the transfer of ownership of funds, and it's the simplest and the most efficient way to do it. So if for some reasons someone needs to share a Bitcoin address with someone else it's better to use a multisig one IMO, it allows to share the ownership in a more convenient way.

I agree. That's why I asked @OP, why would you want to share your private key with someone? There's probably a better way to do it.

[apogio]

Keys are not supposed to be shared though, because on chain transactions are here to prove the transfer of ownership of funds, and it's the simplest and the most efficient way to do it. So if for some reasons someone needs to share a Bitcoin address with someone else it's better to use a multisig one IMO, it allows to share the ownership in a more convenient way.

I agree. That's why I asked @OP, why would you want to share your private key with someone? There's probably a better way to do it.

Bitcoin is based on cryptography as you certainly both know.

I am absolutely confident that OP could simply prove ownership of an address, using the private key that they have, keeping it secret.

Thus, they would be able to "reserve" the bitcoin address, claiming its ownership, using the strongest proof that human has ever invented... cryptography!

OP, you don't reserve the private key, but you can claim ownership of an address using the private key. There is no way to "own" the address, without "owning" the private key. So, in a way, you "reserve" the private key, keeping it secret.

[BlackHatCoiner]

It is not possible to reserve a key, in the sense that you announce to everyone that public key x cannot be used by anyone else. The reason is simple. The only objective way to prove ownership is by signing a message. Therefore, anyone able to sign a message is the true owner of the public key.

It's not a protocol issue or limitation. It just theoretically makes no sense.

[NotATether]

You can't do that, because the Bitcoin network has no mechanism to identify who 'you' are, and consequentially stop other people from using a key in your ownership. This is not PGP, and there's no Web of Trust like you have other there. Bitcoin treats the private key as a unique user.

Most private keys will never be known by any other person, but if they are announced publicly then this ceases to be the case.

[Saint-loup]

You can't do that, because the Bitcoin network has no mechanism to identify who 'you' are, and consequentially stop other people from using a key in your ownership. This is not PGP, and there's no Web of Trust like you have other there. Bitcoin treats the private key as a unique user.

Most private keys will never be known by any other person, but if they are announced publicly then this ceases to be the case.

I'm not sure we can say that "Bitcoin treats the private key as a unique user" as you say because if Satoshi Nakamoto really wanted that, a simple measure would have been to not allow the use of the same address a second time after sending a transaction from it, or at least to create a deadline for using the adress a second time once it has received or sent funds. Currently addresses and keys have an infinite lifespan, so they can be used by your heirs for example or by anyone finding or receiving them.

[NotATether]

I'm not sure we can say that "Bitcoin treats the private key as a unique user" as you say because if Satoshi Nakamoto really wanted that, a simple measure would have been to not allow the use of the same address a second time after sending a transaction from it, or at least to create a deadline for using the adress a second time once it has received or sent funds. Currently addresses and keys have an infinite lifespan, so they can be used by your heirs for example or by anyone finding or receiving them.

We can't change the protocol rules like that, or otherwise stop an address from making multiple transactions.

It would break validation with older clients.

[vjudeu]

We can't change the protocol rules like that, or otherwise stop an address from making multiple transactions.

We can, but we don't want to.

It would break validation with older clients.

It won't. If you reject transactions, which are now valid, then it is just a regular soft-fork. Old clients allow address reuse, so if they see blocks with unique addresses, then they will happily accept all of them as valid.

Also, if you make them non-standard, instead of invalid, then you can apply those rules to your node, and it will work fine, without creating any forks. Then, it could be just a relay-only rule, in the same way, as for example transaction fee is a relay-only rule.

By the way: it is possible to force the user to produce a unique public key for each use of the same address. One example is "<signature> OP_SWAP OP_CHECKSIG". Then, if your sighashes don't use SIGHASH_SINGLE bug, you will get more or less "transaction id", but written as a public key. And then, if we would have sighashes like SIGHASH_ANYPREVOUT, then you could even create covenants, by requiring a given template. Because a constant signature in this model, can achieve pretty much the same, as OP_CHECKTEMPLATEVERIFY could. The only difference is the hashed message, because there is a cyclic dependency between signature in the output, and referenced transaction id in the input.

[garlonicon]

if Satoshi Nakamoto really wanted that, a simple measure would have been to not allow the use of the same address a second time after sending a transaction from it

It is not that simple, because addresses can be keyless. For example: https://mempool.space/testnet4/address/tb1pfees9rn5nz

Also, if you force people to never reuse addresses, then some of them will just increment their keys, and then, you will have "privkey", "privkey+1", "privkey+2", and so on. Note that you can increment the public key, without knowing the private key behind it.

Code:

genesis  =03678AFDB0FE5548271967F1A67130B7105CD6A828E03909A67962E0EA1F61DEB6
genesis+1=03D20A8B8B4D25086D71F03358D26D8564FC199AEFD2A0239C49E9AB4C93A7025E
genesis+2=024F8F115150E8276E6A0F47AB8D885F6B7A989B41643A137C4FA556093C05456E
genesis+3=03B43EEB5FC4F6B3E9F46A8FF8133876D9251A44662F5EDAF916AB1E0B759E0191
...

or at least to create a deadline for using the adress a second time once it has received or sent funds

Then, you could have de-facto transaction expiration, which is explicitly what Satoshi rejected, by saying, that we cannot do OP_BLOCKNUMBER.

We can't safely do OP_BLOCKNUMBER.  In the event of a block chain reorg after a segmentation, transactions need to be able to get into the chain in a later block.  The OP_BLOCKNUMBER transaction and all its dependants would become invalid.  This wouldn't be fair to later owners of the coins who weren't involved in the time limited transaction.