1

Is it possible to enable a 2 of 3 transaction without the escrow component defined as "nobody can run off with the funds but the funds have to exist"

In a scenario where A wants to pay C and requires intermediary B for multisig.

Is it possible for A to authorize a transaction with B and C with one partially signed signature, and then B and C can combine that signature to create a transaction? B and C will have several ways to determine if funds are available from A, but for sake of brevity lets assume A has funds

Improve this question
2
  • I don't understand how this is different from just requiring all 3 signatures?
    – Nate Eldredge
    Apr 8, 2014 at 21:34
  • @NateEldredge ok? please elaborate on what you are talking about , and how A can authorize a payment at Time0 to be pulled at Time1 from the partial signatures given to B and C. If all 3 signatures were required, then A would have to be present at Time0 and Time1
    – CQM
    Apr 9, 2014 at 3:38

1 Answer 1

Reset to default
2
+50

This certainly is possible---but unless you define the "several ways" to verify that A has the funds, the solution must exclude this key component. Here is one possible solution:

Special Multisignature Bitcoin-Address

Create a 3-of-5 multisignature Bitcoin address to which A transfers the Bitcoin in question. A owns 3 of the 5 participating addresses, whilst B and C contribute one each. Next A prepares a partially signed transaction that is signed with only one of his keys.

To eventually access the funds, B and C must both sign this transaction (or ask A for further signing). But it does not tie up the funds in that A can still access the Bitcoin using only his own keys.

Note that this only protects A from either B or C unilaterally taking possession of the bitcoins involved, but it does not offer any reassurance to B or C that the bitcoins will remain available to them in the future. That may create a particularly perverse incentive for intermediary B and recipient C to conspire into splitting the pot among them rather than adhering to whatever B's responsibilities in this matter were supposed to be.

Improve this answer
6
  • Elaborate on why B and C would conspire, as this may reveal what other types of safeguards can be created amongst intermediaries and recipients. Regarding verifying funds are available, B and C could just check the balance of A's address before they (or their script) pull's from it. A contract would detail when payment will be collected. If the blockchain shows a balance too small to cover the payment, then other means of collection will have to be pursued in accordance with the contract (like any other obligation)
    – CQM
    Apr 14, 2014 at 14:28
  • The incentive for B and C to conspire would be taking the payment even when the contracts' conditions for it are not met. Given your plan on how to safeguard against A not paying, you probably want to just design the contract to also safeguard against B and C just taking the pot and splitting it among themselves.
    – user6049
    Apr 14, 2014 at 15:51
  • is this somehow unique from any other multisig scenario?
    – CQM
    Apr 14, 2014 at 15:55
  • @CQM Indirectly, yes. Since typical multisig transactions function as a full escrow, there is no danger that A may unilaterally withdraw the funds, and hence parties B and C don't risk having to resort to going to a court (in case A does try to withdraw). If your contract and contract-enforcement works without incuring any risk or expense for B and C, this does not matter.
    – user6049
    Apr 14, 2014 at 16:47
  • slightly unrelated question, how do you understand multisig so well? I am trying to synthesize use cases, like this question, but information seems to be so scattered or unavailable
    – CQM
    Apr 14, 2014 at 17:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.