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

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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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@ -167,31 +167,40 @@ OP_CHECKTEMPLATEVERIFY as implemented in C++ in the context of Bitcoin Core can
be seen in the reference implementation. be seen in the reference implementation.
The execution of the opcode is as follows: The execution of the opcode is as follows:
def execute_bip_119(self): <source lang="python">
def execute_bip_119(self):
# Before soft-fork activation / failed activation # Before soft-fork activation / failed activation
# continue to treat as NOP4
if not self.flags.script_verify_default_check_template_verify_hash: if not self.flags.script_verify_default_check_template_verify_hash:
# Potentially set for node-local policy to discourage premature use # Potentially set for node-local policy to discourage premature use
if self.flags.script_verify_discourage_upgradable_nops: if self.flags.script_verify_discourage_upgradable_nops:
return self.errors_with(errors.script_err_discourage_upgradable_nops) return self.errors_with(errors.script_err_discourage_upgradable_nops)
return self.return_as_nop() return self.return_as_nop()
# CTV always requires at least one stack argument # CTV always requires at least one stack argument
if len(self.stack) < 1: if len(self.stack) < 1:
return self.errors_with(errors.script_err_invalid_stack_operation) return self.errors_with(errors.script_err_invalid_stack_operation)
# CTV only verifies the hash against a 32 byte argument # CTV only verifies the hash against a 32 byte argument
if len(self.stack[-1]) == 32: if len(self.stack[-1]) == 32:
# Ensure the precomputed data required for anti-DoS is available, # Ensure the precomputed data required for anti-DoS is available,
# or cache it on first use # or cache it on first use
if self.context.precomputed_ctv_data == None: if self.context.precomputed_ctv_data == None:
self.context.precomputed_ctv_data = self.context.tx.get_default_check_template_precomputed_data() 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) 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.errors_with(errors.script_err_template_mismatch)
return self.return_as_nop() return self.return_as_nop()
# future upgrade can add semantics for this opcode with different length args # future upgrade can add semantics for this opcode with different length args
# so discourage use when applicable # so discourage use when applicable
if self.flags.script_verify_discourage_upgradable_nops: if self.flags.script_verify_discourage_upgradable_nops:
return self.errors_with(errors.script_err_discourage_upgradable_nops) return self.errors_with(errors.script_err_discourage_upgradable_nops)
else: else:
return self.return_as_nop() return self.return_as_nop()
</source>
The computation of this hash can be implemented as specified below (where self 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, is the transaction type). Care must be taken that in any validation context,
@ -202,7 +211,8 @@ including hashes of the scriptsigs, sequences, and outputs. See the section
"Denial of Service and Validation Costs" below. This is not a performance "Denial of Service and Validation Costs" below. This is not a performance
optimization. optimization.
def get_default_check_template_precomputed_data(self): <source lang="python">
def get_default_check_template_precomputed_data(self):
result = {} result = {}
# If there are no scriptSigs we do not need to precompute a hash # If there are no scriptSigs we do not need to precompute a hash
if any(inp.scriptSig for inp in self.vin): if any(inp.scriptSig for inp in self.vin):
@ -213,8 +223,8 @@ optimization.
result["outputs"] = sha256(b"".join(out.serialize() for out in self.vout)) result["outputs"] = sha256(b"".join(out.serialize() for out in self.vout))
return result return result
# parameter precomputed must be passed in for DoS resistance # parameter precomputed must be passed in for DoS resistance
def get_default_check_template_hash(self, nIn, precomputed = None): def get_default_check_template_hash(self, nIn, precomputed = None):
if precomputed == None: if precomputed == None:
precomputed = self.get_default_check_template_precomputed_data() precomputed = self.get_default_check_template_precomputed_data()
r = b"" r = b""
@ -235,13 +245,16 @@ optimization.
# pack as 4 byte unsigned integer # pack as 4 byte unsigned integer
r += struct.pack("<I", nIn) r += struct.pack("<I", nIn)
return sha256(r) return sha256(r)
</source>
A PayToBareDefaultCheckTemplateVerifyHash output matches the following template: A PayToBareDefaultCheckTemplateVerifyHash output matches the following template:
# Extra-fast test for pay-to-basic-standard-template CScripts: <source lang="python">
def is_pay_to_bare_default_check_template_verify_hash(self): # 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 return len(self) == 34 and self[0] == 0x20 and self[-1] == OP_CHECKTEMPLATEVERIFY
</source>
==Deployment== ==Deployment==