See above, but to break down that situation a bit further, these are the two situations I can think of:
- The opcode limits user/group A to send the output to user/group B
- The opcode limits user A to send from one address they own to another address they own.
I'm trying to think of a good use case for this type of opcode. In these examples, an attacker who compromises the key for user A can't steal the money because it can only be sent to user B. So if the attacker wants to steal the funds, they would need to compromise the keys of both user A and user B.
But how is that any better than a 2-of-2 multisig? Isn't the end result exactly the same?
James