Let's imagine we have a cold storage wallet that has multiple utxos inside of it and we have a master seed for this wallet.

If we want to spend from coldstorage but want to go first through a new wallet like a coinjoin hot wallet for example we have two alternatives: we could send one single utxo we are interestd in using to that hot wallet or even import the master key to the new wallet (not safe).

It would be very interesting to have a mini-seed of a single utxo from our stash that we could import in the hot wallet and use to spend that single utxo. This way we don't have to create a new tx towards the hot wallet, nor give up information like the whole stash or xpub or subsequent risks of hot wallet.

It would be great to right-click a single utxo on our coldstorage wallet and get the mini seed for that single utxo like another 24 words or 48 words.

Just an idea. Would this be possible?


With existing standards and wallets, no, that is not possible.

Existing standards such as BIP 39 do not directly use the value encoded by the words to produce a BIP 32 HD seed for use in a wallet. Instead they hash the words.

Furthermore, wallets that import that mnemonic do not just use the BIP 32 HD seed from it directly. Instead they use it with derivation paths and derive child keys from it.

If you produced a mnemonic from an individual private key, importing it into any existing wallet would not result in your private key being imported. You would end up with things derived from that private key, but that is not useful to you.

Instead of a mnemonic sentence, what you really want are the Wallet Import Format (WIF) private keys that most wallets can export. WIF is a standard way to encode individual private keys so just use that instead.

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  • But would you see useful something like this added to bitcoin? a way to import the xprv for a single utxo from within a bigger wallet? – zndtoshi Dec 5 '19 at 16:16
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    @zndtoshi I think you're missing the point of Andrew's answer. What you want to do is perfectly possible (though there is a huge caveat), but what you'd import is a private key, not a seed. – Pieter Wuille Dec 5 '19 at 17:31
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    The huge caveat: you really shouldn't do this. In BIP32, when someone knows an xpub and one private key derived from it, they can compute the xprv and all descendant private keys. – Pieter Wuille Dec 5 '19 at 17:32
  • ah ok thank you for the clarification Pieter. – zndtoshi Dec 9 '19 at 19:34

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