davide
0ce0562fd7
A single hostile Electrum server, or a MITM on the one active connection, could fabricate the block header the draw's entropy comes from and so pick the winner of every round: headers were accepted with no proof-of-work check and no link to the previous tip. app/rounds/draw.py adds header_meets_its_own_target (rejects a header whose hash doesn't satisfy the difficulty target it claims) and header_prev_hash. electrum/listener.py's _apply_header now rejects a header failing either check by raising HeaderValidationError, which ends the session the same way a dropped connection would so the listener rotates to the next configured server. ElectrumListener gains corroborate_header: before the draw uses a block, it's independently checked against the other configured servers and needs a majority to agree. rounds/scheduler.py's _wait_for_next_block now calls this and, on failure, logs why and waits for a further block instead of ever using an uncorroborated header. Certificate/hostname verification stays disabled, so this doesn't cover an attacker able to MITM every configured server at once - BUGS.md notes that as not covered. Suite grows from 151 to 165 tests. BUGS.md moves B-28 to Previously fixed.
64 lines
2.4 KiB
Python
64 lines
2.4 KiB
Python
import pytest
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from app.rounds.draw import (
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draw_winner,
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header_hex_to_block_hash,
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header_meets_its_own_target,
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header_prev_hash,
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)
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# Real PLM mainnet block 477486: header from blockchain.block.header, hash
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# cross-checked against the blockhash reported by blockchain.transaction.get for a
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# tx confirmed in that block.
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_REAL_HEADER_HEX = (
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"0020ed30fbc39ee45200d10214f5107c5f36e7bf753032fd1d3279810c170000000000"
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"009a4ea723f732be4c538f3a2490837dd6560103d73ece606aa7d578a66700447b28875"
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"e6a47a61b1ad8012582"
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)
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def test_header_hex_to_block_hash_matches_known_mainnet_block():
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known_block_hash = "00000000000008788b55ade13b74d54ceffda9e54315b802411be1ca65064e86"
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assert header_hex_to_block_hash(_REAL_HEADER_HEX) == known_block_hash
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def test_header_meets_its_own_target_accepts_a_real_mined_header():
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"""B-28: a genuinely mined mainnet header must pass its own self-consistency
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check — this isn't just a synthetic-header property."""
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assert header_meets_its_own_target(_REAL_HEADER_HEX) is True
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def test_header_meets_its_own_target_rejects_a_tampered_header():
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"""Flipping a single nonce bit changes the hash completely (avalanche effect)
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without changing the claimed difficulty, so a tampered-but-otherwise-real
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header should almost certainly fail — this is what would catch a
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hostile/MITM'd server replaying a real header with a doctored field."""
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tampered = bytearray(bytes.fromhex(_REAL_HEADER_HEX))
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tampered[-1] ^= 0xFF # flip the last byte of the nonce
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assert header_meets_its_own_target(tampered.hex()) is False
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def test_header_meets_its_own_target_rejects_wrong_length():
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assert header_meets_its_own_target("aa" * 10) is False
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def test_header_prev_hash_matches_the_known_previous_block():
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# Block 477486's predecessor, 477485 — independently known from the same chain.
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assert header_prev_hash(_REAL_HEADER_HEX) == "000000000000170c8179321dfd323075bfe7365f7c10f51402d10052e49ec3fb"
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def test_draw_winner_is_deterministic_and_within_range():
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participants = ["addrA", "addrB", "addrC"]
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block_hash = "00" * 31 + "05" # seed = 5, index = 5 % 3 = 2
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assert draw_winner(participants, block_hash) == "addrC"
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def test_draw_winner_single_participant_always_wins():
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block_hash = "ff" * 32
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assert draw_winner(["only"], block_hash) == "only"
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def test_draw_winner_raises_on_empty_participants():
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with pytest.raises(ValueError):
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draw_winner([], "00" * 32)
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