Bitcoin Multisig Script
  • N-of-M multisig output script
    • Requires n endorsements from
      m possible signers.

  • Multisig requires extra op-code
    • Multisig consumes one extra op_code.
    • This op_code has no functionality.
    • Requires hardfork to fix this bug.

  • Multisig usually wrapped in P2SH/P2WSH
    • See sections on P2SH and witness transactions.
Example: Multisig Script Signing
    Two parties spend a 2/3 multisig output
    to their respective outputs.
  • 1) Alice builds & signs transaction.
    • Transaction only includes her an output spendable by herself.

  • 2) Bob gets endorsement & Alice's pubkey.
    • Public key allows bob to reconstruct transaction which Alice signed.

  • 3) Bob adds his output and signs.

  • 4) Bob adds endorsements to transaction.
    • Completed transaction spending the multsig output can now be broadcast.