Unsigned / partially signed transaction serialization
A normal serialised transaction with only signatures missing. Each signature is replaced with a single-byte OP_PUSHDATA1 of 0xff. Valid signatures all begin with 0x30 so no confusion is possible.
A signature request wants to be able to add metadata to help the user and wallet to process it:
- Informative message
- Information about each output
- A list of information about required signatures, one per input that is not yet fully signed