2

I've learned that OP_CHECKMULTISIG is a Bitcoin builtin opcode to validate Multisig transactions. Can I write Bitcoin script to validate the Multisig transactions without invoking OP_CHECKMULTISIG? If so, what do I need to change in the redeemScript?

2

Yes, you can use a redeemScript that has a lot of OP_CHECKSIGs and boolean operations. You would have to enumerate all possible combinations of signatures however.

As a simple example, if you used a 2-of-2 multisig, traditionally your redeemScript would be

OP_2 <pubkey1> <pubkey2> OP_2 OP_CHECKMULTISIG

and the scriptSig is then

OP_0 <sig1> <sig2> <redeemScript>

Without OP_CHECKMULTISIG, your redeemScript would be

<pubkey1> OP_CHECKSIG OP_SWAP <pubkey2> OP_CHECKSIG OP_BOOLAND

and the scriptSig would be

<sig2> <sig1> <redeemScript>

For more complex multisigs with more keys and m-of-n, the scripts will be much more complicated with more OP_SWAPs, OP_BOOLORs, and OP_BOOLANDs.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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