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[BIP-119] Use mediawiki syntax highlighting, add comment to spec

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This commit is contained in:
Jeremy Rubin 2022-05-10 08:33:05 -07:00
parent b1791c24aa
commit c8c8e27c2c
1 changed files with 71 additions and 58 deletions
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bip-0119.mediawiki
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@ -167,31 +167,40 @@ OP_CHECKTEMPLATEVERIFY as implemented in C++ in the context of Bitcoin Core can
be seen in the reference implementation.
The execution of the opcode is as follows:
<source lang="python">
def execute_bip_119(self):
# Before soft-fork activation / failed activation
# continue to treat as NOP4
if not self.flags.script_verify_default_check_template_verify_hash:
# Potentially set for node-local policy to discourage premature use
if self.flags.script_verify_discourage_upgradable_nops:
return self.errors_with(errors.script_err_discourage_upgradable_nops)
return self.return_as_nop()
# CTV always requires at least one stack argument
if len(self.stack) < 1:
return self.errors_with(errors.script_err_invalid_stack_operation)
# CTV only verifies the hash against a 32 byte argument
if len(self.stack[-1]) == 32:
# Ensure the precomputed data required for anti-DoS is available,
# or cache it on first use
if self.context.precomputed_ctv_data == None:
self.context.precomputed_ctv_data = self.context.tx.get_default_check_template_precomputed_data()
# If the hashes do not match, return error
if stack[-1] != self.context.tx.get_default_check_template_hash(self.context.nIn, self.context.precomputed_ctv_data)
return self.errors_with(errors.script_err_template_mismatch)
return self.return_as_nop()
# future upgrade can add semantics for this opcode with different length args
# so discourage use when applicable
if self.flags.script_verify_discourage_upgradable_nops:
return self.errors_with(errors.script_err_discourage_upgradable_nops)
else:
return self.return_as_nop()
</source>
The computation of this hash can be implemented as specified below (where self
is the transaction type). Care must be taken that in any validation context,
@ -202,6 +211,7 @@ including hashes of the scriptsigs, sequences, and outputs. See the section
"Denial of Service and Validation Costs" below. This is not a performance
optimization.
<source lang="python">
def get_default_check_template_precomputed_data(self):
result = {}
# If there are no scriptSigs we do not need to precompute a hash
@ -235,13 +245,16 @@ optimization.
# pack as 4 byte unsigned integer
r += struct.pack("<I", nIn)
return sha256(r)
</source>
A PayToBareDefaultCheckTemplateVerifyHash output matches the following template:
<source lang="python">
# Extra-fast test for pay-to-basic-standard-template CScripts:
def is_pay_to_bare_default_check_template_verify_hash(self):
return len(self) == 34 and self[0] == 0x20 and self[-1] == OP_CHECKTEMPLATEVERIFY
</source>
==Deployment==