Mining and block signatures

In MultiChain, block creators must prove their identity by signing blocks

Block signatures

Block signatures are embedded inside the OP_RETURN metadata of the coinbase transaction, using a regular bitcoin-style signature format. The payload signed by the block creator is the full block header, with the following modifications:

• The merkle_root is recalculated based on the txid of the coinbase transaction with the OP_RETURN removed. This prevents a dependency loop from block signature → coinbase txid → merkle root → block header → block signature.
• In protocol versions up to 20005, or in later protocols with blockchain parameters where pow-minimum-bits>12 or target-adjust-freq>0, the nonce field is set to 0. This avoids having to recalculate the signature for every attempt at finding a block hash to match the target difficulty. However it does lead to some malleability in that a user without mine permissions could generate a block with the same content as a valid block, but with a different nonce.