offline address - or a way to explicitly freeze an address

[btcusr]

Frozen / Locked / Offline addresses

What is a 'frozen' address?
    An address locked for spending (but yet it can receive money)

Why you want to 'freeze' an address?
    To prevent spending in case of stolen / compromised private key

How is that possible?
    Simple. protect it with another key.

How you protect this 'freeze' key?
    Generate offline. Use one key only once (twice, for lock and unlock)

but, turtles all the way down?
    two turtles better than one turtle?  

What is made possible now by this 'freezing'?
    you can use your cool firstbits address forever without worrying about stolen key

Why so much attachment to some random bit, after all it is free?
    may be it is trivial in my case (1vijay), but what about these firstbits 1, 1paypall, 1citi, 1microsoft, 1google, etc.

Is this some kind of planned loophole / backdoor that allows access to .. ?
    no, only who can spend can freeze

How safe is this 'frozen' address ?
    the safest; safer than a paper wallet

Safer than a paper wallet?
    yes, spending is prevented by implementations

The safest, huh?
    yes, hm.. I mean, only as safe as your 'freeze' key

How will this be implemented?
    A team working on this (now, its only me)

I want this to be implemented, what can I do?
    let the world know. participate in the poll of this thread

(to be continued)

[DannyHamilton]

You can generate an address offline.

As long as you keep the private key secret, nobody can steal the bitcoin.

[btcusr]

Any comments?

[Walter Rothbard]

Any comments?

DannyHamilton told you how people implement this today.

[btcusr]

Yes, I am aware of addresses generated offline, and tools used to generate addresses offline.  But, I tried to import private key to my block chain.info wallet and password protected wallet is backed up to many places. My password is quite strong, but I want to have more security for my wallet / address. Like, if I could externally freeze spending from my addresses, I think that would be great.

Whenever I want to spend btc I can unfreeze specific address for short period of time, and then freeze them again (by signing with different keys every time??).

This way I don't have to worry about my wallet getting stolen, because my addresses were frozen for spending.

All this is for I want to keep my firstbit addresses (1vijay, 1visu) forever. I still can create multi-sign (3xx*) addresses with one of these addresses part of it, but that's entirely different story.

[btcusr]

I will try to explain further with detailed examples, implementation and pros/cons later.

[markm]

So how do you freeze your address-sealing keys, to make sure no-one can use them to unfreeze your frozen accounts?

Its turtles all the way down.

-MarkM-

[btcusr]

Good question. I am not planning to freeze my second key, instead I will change them as I prefer. I mean I will freeze with third key, and then unfreeze with second key, so now I would need only third key to unfreeze my address. One unfreezed, now I can use my first private key to spend btc. Immediately after spending I will freeze my address again with third or another new key (4th).

If somehow we can implement this to blockchain, then it would really be useful for everyone.

[kjj]

No.  This can't be done.

Transactions in bitcoin simply don't work they way you think they do.  Sorry.

[btcusr]

Why you think it is not useful, or can't be done?

[btcusr]

I still believe this kind of address freezing is the bestest safest way to store / exchange coins.

I will try to explain it further.

[btcusr]

It is not useful because if you had a "locked" address and also the authority to "unlock" that address, then basically it would be the same as having the private key.

but with the ability to change second "unlock" key will be useful in many cases. so the first address remains safe always, and can receive money even when it was locked.

[btcusr]

Now something similar to offline addresses mentioned above, can be done using multi-sign addresses, but in this case, new address keep changing, so it is not possible to use single address for receiving funds forever.

Now to answer an important question, when address creation is so cheep why you want to use one address forever? well, I got my firstbit addresses (1vijay and 1visu) and I don't want to loose it. Using one address as main address for all transactions, and protecting with second set of keys for freeze / unfreeze purposes, is preferable in many cases.

[btcusr]

when I was reading through bitcoin.it, I found some concepts related to this 'offline / frozen address' do exist with bitcoin eco-syatem; like, nlocktime, exit address and contracts.

[jl2012]

You can simply leave the private key of your vanity address in an offline client such as Armory. Locking private key X with private key Y gives you no extra security than 2-of-2 multisig with X and Y

[btcusr]

You can simply leave the private key of your vanity address in an offline client such as Armory. Locking private key X with private key Y gives you no extra security than 2-of-2 multisig with X and Y

No, I have already imported it to my Blockchain.info wallet. Again, addresses generated offline is not the same as 'frozen' addresses. 'Frozen' addresses only receive, and will not spend funds.

With 2x2 scheme receiving addresses keep changing.

May be I should put less emphasis on addresses, and throw away old addresses, after all it is free. But, I prefer to keep it forever.

[btcusr]

Exploring 'script', and checking possibilities to define public address and firstbits-like shorthand notation (say 'secondbits') outside block chain. With this, I can keep one shorthand address notation and associate it with any public addresses.

And, I have to do this in a way that users don't have to trust 'secondbits' provider.

[John (John K.)]

It would require a huge rework of the Bitcoin code, and introduce a hard fork to the blockchain. What you mentioned can be done by using a time-based 2-part signature service, much like TTBit was offering some time ago, but a more practical and secure way would be to generate the address using some offline utility like Vanitygen and print the keys out.

tl;dr: No.

[TTBit]

We still offer it. lbaat.net. Although not sure it would satisfy what you are trying to accomplish

[btcusr]

It would require a huge rework of the Bitcoin code, and introduce a hard fork to the blockchain.

I am sure it wouldn't require lots of code changes. With some (lot) effort, I can implement all this myself. Real question is should we implement this, and what benefits it bring to the Bitcoin ecosystem.

And, no, surely it wouldn't require a hard fork, and this 'freeze' transaction is not meant to change already created blocks. It is only for new blocks (of course old addresses already in the block can also be used), it will also include transaction fees.