Normally when you use OP_CHECKMULTISIG you're basically setting up something like x-of-y, where any x of the y key holders can carry out a transaction.

I want to know, if you can repurpose this operation in some way, so that its not just any x, but one of those x-keys needs be a specific party. How could you define a scriptPubKey such that the specific party is required and any 1 one of the remaining parties.

1 Answer 1


That is possible, you could use a custom P2SH contract with redeem script like:


This script always requires a signature from key1, and a signature from either key2 or key3, making this a 1 AND 1/2 scheme. It would be spent using:


but it could be extended to any L AND M/N, as long as it can fit inside Script VM limits.

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