Ryan Henry
0d22946a0e
Ship the TLS mesh, composer, Beaver/Yao/leaf MPC, prep/online paths, apps, and docs so the tree is pushable before elevating share_expr, security_mode, and prep resume. Co-authored-by: Cursor <cursoragent@cursor.com>
31 lines
1.7 KiB
Markdown
31 lines
1.7 KiB
Markdown
# Verifiability & authenticity {#verifiability}
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\htmlonly
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<div class="eli5"><b>ELI5.</b> The proof rides on the same walk as the payload. verifiable checks that the correction seeds were the honest ones. extractable checks that the path is weight 1, so a second programmed point fails. A MAC checks the leaf share after it is opened.</div>
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\endhtmlonly
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Prove that a DPF walk used honest correction seeds, or that a weight-1
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sketch over the path is consistent. The tags ride along as extra
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`make_dpf` arguments; eval still returns the usual leaf share.
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| Tag / call | What you get |
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| --- | --- |
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| [dpf::verifiable](@ref dpf/verifiable.hpp) | Proof token folded on the path (de Castro–Polychroniadou, EUROCRYPT 2022 / [ePrint 2021/580](@ref bib_vdpf)). Equal tokens across parties mean honest seeds. |
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| [dpf::extractable](@ref dpf/verifiable.hpp) | Weight-1 `fp61` sketch on the same walk. A second hot point fails the check. |
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| [dpf::output_mac](@ref dpf/verifiable.hpp) / `mac_authenticate` | Authenticated leaf shares and batch checks. |
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| Path sketches | [path_sketch.hpp](@ref dpf/path_sketch.hpp) for prefix / parent sketches used by application mockups. |
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```cpp
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auto [k0, k1] = dpf::make_dpf(std::uint8_t{42}, std::uint64_t{7},
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dpf::verifiable{});
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auto [e0, e1] = dpf::make_dpf(std::uint8_t{42}, std::uint64_t{7},
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dpf::extractable{});
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```
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Multipoint keys take the same `dpf::verifiable{}` tag for a batched
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proof (one token for the cuckoo set). Three-party keys can be
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verifiable or extractable as well; see [Multiparty & 3-server](@ref multiparty).
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**Go deeper:** [guided tour](@ref tour_vdpf), ideal figures
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[F_VDPF](@ref verifiable.hpp) / [F_Sketch](@ref verifiable.hpp),
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[bibliography](@ref bibliography).
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