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42 lines
1.4 KiB
Python
42 lines
1.4 KiB
Python
 
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"""Helpers for working with minimal SortedMulti descriptor templates."""
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from __future__ import annotations
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from dataclasses import dataclass
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from typing import Sequence
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@dataclass(frozen=True)
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class SortedMultiDescriptorTemplate:
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"""Minimal representation of a ``wsh(sortedmulti(m, ...))`` descriptor."""
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threshold: int
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def witness_script(self, tweaked_keys: Sequence[bytes]) -> bytes:
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"""Return the witness script for ``wsh(sortedmulti(threshold, tweaked_keys))``."""
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if not tweaked_keys:
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raise ValueError("sortedmulti requires at least one key")
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if not 1 <= self.threshold <= len(tweaked_keys):
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raise ValueError("threshold must satisfy 1 <= m <= n")
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for key in tweaked_keys:
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if len(key) != 33:
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raise ValueError("sortedmulti keys must be 33-byte compressed pubkeys")
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sorted_keys = sorted(tweaked_keys)
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script = bytearray()
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script.append(_op_n(self.threshold))
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for key in sorted_keys:
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script.append(len(key))
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script.extend(key)
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script.append(_op_n(len(sorted_keys)))
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script.append(0xAE) # OP_CHECKMULTISIG
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return bytes(script)
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def _op_n(value: int) -> int:
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if not 0 <= value <= 16:
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raise ValueError("OP_N value out of range")
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if value == 0:
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return 0x00
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return 0x50 + value
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