Multisig Help!

[ihatemultisig]

Hey guys,

Is there any way to change the output address of a multisig transaction.  I've got a bunch of timelock tx's but they are all pre-signed to go to an address that I no longer have access to.  I've got the private key to sign the transaction itself, and I've got the timelock TX to sign, but there's got to be some way to re-build the tx from scratch without having to have one of the other parties re-sign the TX.

Here's a sample TX

0100000001226eb050250cfe1c0d46bf2a2433e5f8a7999caea005680c7c71f69d694c744000000 000b500483045022100beedd69a6dab057d8186410a369f74028ae680f6cfa19da708a262f654ea 786802204ef282d6c45e50557808cc11c5075c649f9d2696fc00e0e20570b09c84da2071014c695 22102047fb81b818e7062f67becf3061cfd79eab5f0efed9f4643a3589a6765bedbff21026e2dfc be33a108339aad2c316f8b3dcfd782c7d2244ffe3cc40a2533ef02a68d2102c2dedfb1f2ca61dfe 2d9799ee772e2bbd1667aaa66c904cc3916dbcda7a3831453aedaad59ff0196ca6c000000000019 76a914fe5cfe0673e3fd95bef56f6ff0c5d69a499f525488ac8d01df59

If you verify it in coinb.in, you can see it's been signed by one party but it has an output address of 1QBx2weexpYZcRwMs5dXGJfMY8TFK6mwH1

I'm pretty sure that address belongs to a web based wallet that no longer works and I've tried reaching out to the support team of the company with no luck.

If anyone can help me figure this out, I'll pay a .5 BTC reward.

Thanks

[ranochigo]

You can't. Multisig transactions are designed in a way that they would only be valid if n in the n-of-m multisig signatures have signed the transactions. If it doesn't work this way, then there would be no point for multisig to exist then.

Is it a 2-of-2 multisig?

[ihatemultisig]

They are 2 of 3.  They are already signed by one party, and I'd be the 2nd when I sign them.  But by singing it and broadcasting it as is, it will just go to a BTC address I no longer have access to.

[ranochigo]

They are 2 of 3.  They are already signed by one party, and I'd be the 2nd when I sign them.  But by singing it and broadcasting it as is, it will just go to a BTC address I no longer have access to.

Who holds the other keys? Since the wallet provider has closed, can you find the other party? Your one and only solution is to find either of the other two party and ask them to sign it.

[ihatemultisig]

Alright I guess I'll have to see if I can hunt down all of the folks and get their private keys for the TX's.  Even then, I have no idea how to pull a redeem script from the original transaction and rebuild it to have a new output address.

[ranochigo]

It's pretty easy to get the redeem script. Your address is 3KQZQMdKPaQKtZRwmxmKXVuP8yzcT8Wa21 right?

Your redeem script is:522102047fb81b818e7062f67becf3061cfd79eab5f0efed9f4643a3589a6765bedbff21026e2df cbe33a108339aad2c316f8b3dcfd782c7d2244ffe3cc40a2533ef02a68d2102c2dedfb1f2ca61df e2d9799ee772e2bbd1667aaa66c904cc3916dbcda7a3831453ae.

The three addresses that you need to find are: 1ArKP1KnNBWY4KA5SqhEWyu6cuLUEpZ18f, 1FTsJTZMUM7uE9eaQH2pLvEEFtbBrtWuLx and 1P7bpk6v1rjWJpxNkcsrc7CVNHCV4uhxPS.

[ihatemultisig]

Alright, how do you pull all of that from the TX I posted?

The 1FTsJTZMUM7uE9eaQH2pLvEEFtbBrtWuLx is me, so that's the key I hold in the equation.  I just need to find one of the other keys to sign it with and then I can build a new transaction sending to a new output address it looks like.

Hard part will be tracking down alllllll of the different people to get their keys if they still have them, haha.

Thanks