[bitcoin-dev] To-be-softfork policy in 0.13.1

[Johnson Lau]

Coupled with the release of segwit in 0.13.1, there are 3 default relay and mining policy rules that may become softfork proposals in the near future.

Generally, users must not assume that a script spendable in pre-segregated witness system would also be spendable as a P2WPKH or P2WSH script. Before large-scale deployment in the production network, developers should test the scripts on testnet with the default relay policy turned on, and with a small amount of money after BIP141 is activated on mainnet.

The rules include:

1. Only compressed public keys are accepted in P2WPKH and P2WSH (See BIP143 for details)
2. The argument of OP_IF/NOTIF in P2WSH must be minimal (see https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-August/013014.html)
3. Signature(s) must be null vector(s) if an OP_CHECKSIG or OP_CHECKMULTISIG is failed (for both pre-segregated witness script and P2WSH. See BIP146)

The BIP141 and 143 are updated with the aforementioned rules: https://github.com/bitcoin/bips/pull/459/files