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>
92 lines
4.9 KiB
Markdown
92 lines
4.9 KiB
Markdown
# Network, parties, and MPC around the keys {#network_and_mpc}
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<div class="eli5"><b>ELI5.</b> The library is about DPFs first. The same headers also wire the parties together, schedule rounds, multiply and garble leaf shares, write leveled run logs, and emit paper-cost statistics — so a PIR or Duoram sketch does not start from bare sockets.</div>
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Keys and evaluation are the core story. This page is the map of everything
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that sits *around* those keys when you run a real protocol: links, party
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roles, composition, arithmetic and boolean MPC on leaf shares, logging, and
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cost instrumentation. Open a linked page for the details; the [call index](@ref api_reference)
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lists the headers.
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## Network and party mesh
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| Piece | Role |
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| --- | --- |
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| [party_session](@ref dpf/net/party_session.hpp) | One role joins a mesh: dial/accept, lanes, reconnect, dealer link |
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| [trio](@ref dpf/net/trio.hpp) | Convenience `(2+1)` mesh (`p0`, `p1`, dealer `p2`) |
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| [TLS 1.3](@ref dpf/net/tls.hpp) / [security](@ref dpf/net/security.hpp) | Default on peer links; `--encryption=off` for plaintext benches |
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| [RoundSink](@ref dpf/net/round_sink.hpp) / [edge_mesh](@ref dpf/net/edge_mesh.hpp) | Batched exchange rounds on star / clique / dealer topologies |
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| [stream arrays](@ref dpf/net/stream_array.hpp) | Sync or async TCP (and optional SCTP) byte lanes |
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Processes may start in any order: lower ids accept, higher ids connect and
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retry. After connect (or TLS handshake) both ends exchange a fixed hello so
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mismatched party id, epoch, transport, or lane count fail at join time.
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```cpp
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// Conceptual shape — see party_session / trio headers for the full API.
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dpf::net::session_options opt; // TLS on by default
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dpf::net::party_session session(/*role*/, opt);
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session.join(/*host:port table*/); // or in-process rendezvous
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auto & sink = session.round_sink(/*peer*/);
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```
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**Go deeper:** [trio.hpp](@ref dpf/net/trio.hpp),
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[party_session.hpp](@ref dpf/net/party_session.hpp),
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[secure_channel.hpp](@ref dpf/net/secure_channel.hpp),
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examples under `examples/protocol/`.
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## Protocol composition
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[dpf::protocol::composer](@ref protocol_compose) records FSS walks, Beaver
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opens, and reshares as one RoundSink plan. Share domains are tagged
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(`fss`, `a`, `b`, `rss`, `y`); party-count changes are explicit `reshare`.
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Independent opens share a wave; dependency chains become successive waves.
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Drive with `drive` / `drive_via_schedule`, or party helpers
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`util::drive_composed` / `util::drive_composed_trio`. Named application
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skeletons (PIR upload/answer, SUBLEQ, hushmap, …) live in
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[app_plans.hpp](@ref dpf/app_plans.hpp).
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**Go deeper:** [Protocol composition](@ref protocol_compose).
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## MPC on leaf shares
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The DPF answers the secret index. What you do *with* the opened (or still
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shared) leaf is ordinary MPC in the same library:
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| Tool | When you reach for it |
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| --- | --- |
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| [Beaver triples](@ref beaver_triples) | Products, dots, polynomials, optional MACs (ABY2.0) |
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| [Arithmetic share runtime](@ref arith_runtime) | edaBits, truncate, share compare, matmul, hidden shuffle |
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| [Yao on a leaf](@ref yao_leaf) | A boolean circuit the key does not contain; half-gates |
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| [Dealer-free keygen](@ref dealer_free) | Doerner–Shelat / IKNP when nobody deals the pads |
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| [Multiparty & 3-server](@ref multiparty) | `(2,3)` Shamir spines or IT three-server tables |
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**Go deeper:** those capability pages, then the [guided tour](@ref guided_tour)
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sections on Beaver, Yao, and running protocols.
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## Logging and statistics
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Observability is first-class, not an afterthought:
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| Facility | Role |
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| --- | --- |
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| [Run log](@ref run_log) (`log.hpp` / `run_log.hpp`) | Leveled `key=value` lines to stderr, syslog, or a file; provenance banner (build, host, argv, env, config); link and trial events |
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| [Statistics & CSVs](@ref statistics) (`experiment.hpp`) | Replayable master seeds, per-party streams, wire bytes, rounds, wall/CPU, symmetric-key blocks by purpose×primitive |
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| [`prg::count`](@ref dpf/prg_count.hpp) | Thread-local expand / hash / harness counters (AES, ChaCha, LowMC) |
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| [`thread_work`](@ref dpf/thread_work.hpp) | Charge compute-pool kernels back to the owning party |
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In-tree `party/` drivers and `run_parties` / `app::run` / `app::run_measured`
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call `app::start_logging` and drive the mesh end-to-end. Before any party
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starts its clock, all parties wait at a start gate.
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**Go deeper:** [Logging, statistics, and experiments](@ref experiment_costs),
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[compose.hpp](@ref dpf/compose.hpp),
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[experiment.hpp](@ref dpf/experiment.hpp),
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[log.hpp](@ref dpf/log.hpp).
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\htmlonly
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<div class="tldr"><b>TL;DR.</b> Start with make_dpf and eval. When you need live parties, party_session / trio give TLS links and RoundSink rounds; the composer schedules FSS next to Beaver and Yao; start_logging and experiment stamp the run log and paper CSVs. The keys stay the product — the net, MPC, logging, and statistics stack is how you run and measure them.</div>
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\endhtmlonly
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