22 lines
923 B
Python
22 lines
923 B
Python
 
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import hashlib
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def header_hex_to_block_hash(header_hex: str) -> str:
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"""Block hash from a raw Electrum header: sha256d, byte-reversed, hex.
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Verified against a real mainnet block (blockchain.transaction.get's own
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reported blockhash) during development."""
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header_bytes = bytes.fromhex(header_hex)
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digest = hashlib.sha256(hashlib.sha256(header_bytes).digest()).digest()
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return digest[::-1].hex()
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def draw_winner(participants: list[str], block_hash_hex: str) -> str:
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"""v1 draw algorithm (flowchart.mmd, node R): seed = block hash as an integer,
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index = seed mod participant_count, winner = participants[index]. Anyone can
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recompute and verify it from public data. Deliberately simple/replaceable."""
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if not participants:
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raise ValueError("no participants to draw from")
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seed = int(block_hash_hex, 16)
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index = seed % len(participants)
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return participants[index]
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