Add Transmission-verified golden vectors for hybrid v1+v2 hashes#8
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Closes the review's open 'is the v2 Merkle padding BEP 52-correct?' question. Verified empirically with Transmission 4.1.2: for single-file (partial final piece), non-power-of-two piece count, and multi-file layouts, transmission-remote --verify recomputed the v1 piece SHA-1s and the v2 block/Merkle piece-layer from raw bytes and reported 100% / no error — i.e. a real reference client accepts our hybrid torrents as valid. The flagged 'critical' Merkle finding was a false positive. This test pins the v1+v2 info hashes for two fixed inputs (1MB uniform -> 4 pieces; 700KB pattern -> 3 pieces) so the Merkle construction can't silently regress. Regeneration steps are in the test doc comment.
iksnerd
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Jun 21, 2026
Add Transmission-verified golden vectors for hybrid v1+v2 hashes
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Closes the one open question from the 2026-06-13 review: is the v2 Merkle piece-layer padding actually BEP 52-correct for multi-piece files? The review flagged it "critical (pending reference-client confirmation)" — and the tell was that the agent's own worked examples kept coinciding with the spec.
What I did
Installed
transmission-cli4.1.2 (BEP 52 / hybrid support landed in Transmission 4.0) and had it independently re-derive hashes from raw bytes viatransmission-remote --verify— which recomputes the v1 piece SHA-1s and the v2 block + Merkle piece-layer and checks them against our.torrent. Tested the exact cases the review worried about:A real reference client accepts our hybrid torrents as fully valid. The "critical" Merkle finding was a false positive.
This PR
Pins the v1+v2 info hashes for two fixed (deterministic) inputs as a golden-vector regression test, so the Merkle construction can't silently break. The values are trustworthy because Transmission verified the corresponding data. Regeneration steps are in the test doc comment.
Pure unit test — no Transmission dependency in CI.
Verification
go test ./...passes including the newTestHybridGoldenVectors.🤖 Generated with Claude Code