well how come if heard many times that multisig implementations are not cross compatible between one client and another? Il have to look into multisig more..
If they are not cross compatible how come they get confirmed by blockchain (miners)? There must be some core functionality that is same for it to work on entire bitcoin network.
Maybe the problem is that you have to manually send/notify the transaction to other person? bingo.
only the actual sending of coins once all signatories have signed is sent out on the block chain when using client side multisig. the actual request to sign a transaction, as far as i know, is not.
Bitcoin multisig implementations need a "combiner". First person signs, then gets passed to the second and third person (if 2 of 3). If any one of them signs then it goes to the combiner and the condition would have been met. The combiner can but not necessarily be one of the three wallets. It can be a creator of the transaction only and not one of the 3 signatories. Once 2 of three sign, the combiner will then see a "true" condition with a long digital signature. This is then broadcast to the block chain as an actual spend. If the combiner is offline, nothing will be broadcast and the transaction will stay in a hung state until the combiner is online and the script in the combiner is run using bitcoind to send transaction.
Essentially, this is what we call a wallet based on m of n multisigs. All coins today, if they implement multsig at all, use this method. The critical bottleneck is the combiner. Once off line nothing gets transacted. A '3' at the front does not mean anything more than an indicator that it is a multisig address created from m of 3 signatories (therefore 3 as the prefix). It will require m number of addresses to create the multisig address. Theoretically an m of n can still implement a multisig based on the address with a prefix 1. It doesn't prevent any wallet software from doing that, simply because it is a wallet based multisig and the block chain recognises it as a valid Bitcoin address.
In short, the digital signatures of m of n are combined to form the key to sign off the transaction of this multisig account. When they are combined, some machine somewhere must be online to combine it.
Edit: Two wallets implementing multisigs of their own will not talk to each other unless they are using the same implementation solution. Theoretically, one can use the public key of the other wallet, as one of the signatories but the other wallet will have no idea about its "involvement" in this wallet if it runs its multisig using its own software solution.
