public inbox for bitcoindev@googlegroups.com
 help / color / mirror / Atom feed
From: アルム カールヨハン <karl@dglab•com>
To: Anthony Towns <aj@erisian•com.au>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Simple lock/unlock mechanism
Date: Thu, 1 Mar 2018 05:11:54 +0000	[thread overview]
Message-ID: <CALJw2w5TqjYVAEUVMa9BVaqscoqXAs3xD65vP3kMfxmPTqD9Eg@mail.gmail.com> (raw)
In-Reply-To: <20180228223044.GA31415@erisian.com.au>

On Wed, Feb 28, 2018 at 10:30 PM, Anthony Towns <aj@erisian•com.au> wrote:
> On Wed, Feb 28, 2018 at 04:34:18AM +0000, アルム カールヨハン via bitcoin-dev wrote:
>> 1. Graftroot probably breaks this (someone could just sign the
>> time-locked output with a script that has no time-lock).
>
> Making the graftroot key be a 2-of-2 muSig with an independent third party
> that commits to only signing CLTV scripts could avoid this. Making it
> 3-of-3 or 5-of-5 could be even better if you can find multiple independent
> services that will do it.

That kind of defeats the purpose. If you go through the trouble of
doing that, you can just do multisig and skip the freezing part
entirely. A robber would have to get you and the cosigner to sign in
both cases, and the CLTV could be overridden with graftroot.

On Wed, Feb 28, 2018 at 11:36 PM, Adam Back <adam.back@gmail•com> wrote:
> Coincidentally I had thought of something similar to what Kalle posted
> about a kind of software only time-lock vault, and described the idea
> to a few people off-list.  Re. Root incompatibility, if the key is
> deleted (as it must be) then a delegated signature can not be made
> that bypasses the CSV timeout restriction, so Root should not be
> incompatible with this.  I think it would be disadvantageous to mark
> keys as Rootable vs not in a sighash sense, because then that is
> another privacy/fungibility loss eroding  the uniformity advantage of
> Root when the delegate is not used.

1. Create TX1=(tx, sig) from UTXO A to p2sh B which has a CSV
timelock. Discard privkey A.
2. After broadcasting TX1, you need privkey B to spend it.
3. Use graftroot and privkey B with a script without timelock to spend B.

The robber can simply force you to execute step 3, since you have the
privkey to B.

> One drawback is deleting keys may itself be a bit difficult to assure
> with HD wallet seeds setup-time backup model.

That's a good point. Even more of a reason to include as part of
'freezing' a send to a new ephemeral key as 'initialization'. Sucks to
pay triple fees though (freeze ephemeral + unfreeze + actual use).

> As Anthony described I think, a simpler though less robust model would
> be to have a third party refuse to co-sign until a pre-arranged time,
> and this would have the advantage of not requiring two on-chain
> transactions.

I was hoping there was a way for a person to simply lock-up the major
portion of their coins easily.

As a sidenote: a security firm (e.g. one that comes to your house when
the alarm goes off) could have a service where seeing an unfreeze
transaction which you have told them about without you giving a heads
up beforehand is equal to alarm going off.

-Kalle.


  parent reply	other threads:[~2018-03-01  5:12 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-28  3:47 アルム カールヨハン
2018-02-28  4:34 ` アルム カールヨハン
2018-02-28 22:30   ` Anthony Towns
2018-02-28 23:36     ` Adam Back
2018-03-01  5:11     ` アルム カールヨハン [this message]
2018-03-05 14:53       ` アルム カールヨハン

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CALJw2w5TqjYVAEUVMa9BVaqscoqXAs3xD65vP3kMfxmPTqD9Eg@mail.gmail.com \
    --to=karl@dglab$(echo .)com \
    --cc=aj@erisian$(echo .)com.au \
    --cc=bitcoin-dev@lists$(echo .)linuxfoundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox