Match stored content on BLAKE3 alone, so a browser can afford to ask

Performancekamo-shared-library
Shipped
August 9, 2026 at 6:16 PM UTC
Author
Kamo
Commit
84bbe81

Proving possession required both hashes, and a browser has no fast SHA3-256 — js-sha3 is pure JavaScript at ~25 MB/s. Measured on a 358 MB video that was ~20 seconds of hashing against an 18.8 second upload, so dedup saved the bandwidth and handed the time straight back. From the member's side it was indistinguishable from uploading. Adds a lookup on BLAKE3 plus exact size, which BLAKE3's WASM build computes roughly twenty times faster. A 256-bit digest and an exact byte count identify content beyond practical doubt, and the property that matters is untouched: a caller can only name content it actually holds, resolved within its own dedup scope. Storage still records both hashes — this narrows the lookup, never what is stored.

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