Skip to content

Commit

Permalink
[BIP-119] Make it abundantly clear that policy and standard are recom…
Browse files Browse the repository at this point in the history
…mendations.
  • Loading branch information
JeremyRubin authored Jan 26, 2022
1 parent 9eb17cd commit 5901e70
Showing 1 changed file with 14 additions and 12 deletions.
26 changes: 14 additions & 12 deletions bip-0119.mediawiki
Original file line number Diff line number Diff line change
Expand Up @@ -274,14 +274,14 @@ For the avoidance of unclarity, the parameters to be determined are:
consensus.vDeployments[Consensus::DEPLOYMENT_CHECKTEMPLATEVERIFY].min_activation_height = 0;
Until BIP-119 reaches ACTIVE state and the
SCRIPT_VERIFY_DEFAULT_CHECK_TEMPLATE_VERIFY_HASH flag is set, the network should
execute a NOP4 as SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS for policy and a NOP for
consensus.
SCRIPT_VERIFY_DEFAULT_CHECK_TEMPLATE_VERIFY_HASH flag is enforced, node implementations should (are recommended to)
execute a NOP4 as SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS (to deny entry to the mempool) for policy and must evaluate as
a NOP for consensus (during block validation).

In order to facilitate using CHECKTEMPLATEVERIFY, the common case of a
PayToBareDefaultCheckTemplateVerifyHash
with no scriptSig data shall be made standard to permit relaying. Future template types may be
standardized later as policy changes.
with no scriptSig data may (is recommended to) be made standard to permit relaying. Future template types may be
standardized later as policy changes at the preference of the implementor.

==Reference Implementation==

Expand Down Expand Up @@ -592,12 +592,13 @@ reuse-unsafe.
Because CHECKTEMPLATEVERIFY commits to the input index currently being spent, reused-keys are
guaranteed to execute in separate transactions which reduces the risk of "half-spend" type issues.

====NOP-Default and Standardness Rules====
====NOP-Default and Recommended Standardness Rules====

If the argument length is not exactly 32, CHECKTEMPLATEVERIFY treats it as a NOP.
Many OP_NOP upgrades prefer to fail in such circumstances. In particular, for
CHECKTEMPLATEVERIFY, making an invalid argument a NOP permits future soft-forks to upgrade the
semantics or loosed restrictions around the value being previously pushed only.
If the argument length is not exactly 32, CHECKTEMPLATEVERIFY treats it as a NOP during
consensus validation. Implementations are recommended to fail in such circumstances during non-consensus
relaying and mempool validation. In particular, making an invalid-length argument a failure aids future
soft-forks upgrades to be able to rely on the tighter standard restrictions to safely loosen
the restrictions for standardness while tightening them for consensus with the upgrade's rules.

The standardness rules may lead an unscrupulous script developer to accidentally rely on the
stricter standardness rules to be enforced during consensus. Should that developer submit a
Expand Down Expand Up @@ -713,8 +714,9 @@ for an OP_NOP are a soft fork, so existing software will be fully functional wit
for mining and block validation. Similar soft forks for OP_CHECKSEQUENCEVERIFY and OP_CHECKLOCKTIMEVERIFY
(see BIP-0065 and BIP-0112) have similarly changed OP_NOP semantics without introducing compatibility issues.

In contrast to previous forks, OP_CHECKTEMPLATEVERIFY's implementation does not allow transactions with spending
scripts using it to be accepted to the mempool or relayed under standard policy until the new rule is active.
In contrast to previous forks, OP_CHECKTEMPLATEVERIFY's reference implementation does not allow transactions with spending
scripts using it to be accepted to the mempool or relayed under standard policy until the new rule is active. Other implementations
are recommended to follow this rule as well, but not required.

Older wallet software will be able to accept spends from OP_CHECKTEMPLATEVERIFY outputs, but will
require an upgrade in order to treat PayToBareDefaultCheckTemplateVerifyHash chains with a confirmed ancestor as
Expand Down

0 comments on commit 5901e70

Please sign in to comment.