feat(threshold): add context-bound derivation and FullIdent wrapping

.github/workflows/rust.yml

@@ -27,6 +27,44 @@ env:
 # crates for wasm32-unknown-unknown — is now a real, unconditional step in the
 # `build` job.
 jobs:
+  threshold:
+    name: threshold (crate, policy, primitive checker)
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    env:
+      CARGO_TARGET_DIR: target/threshold
+      PROPTEST_CASES: "1024"
+    steps:
+    - uses: actions/checkout@v4
+    - uses: dtolnay/rust-toolchain@1.97.1
+      with:
+        components: clippy, rustfmt
+    - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6
+      with:
+        shared-key: threshold-1.97.1
+        workspaces: . -> target/threshold
+    - name: Run the complete threshold crate suite
+      run: cargo test --locked -p tinycloud-threshold --release
+    - name: Install pinned cargo-deny
+      run: |
+        set -euo pipefail
+        tool_dir="${RUNNER_TEMP}/threshold-cargo-deny"
+        mkdir -p "${tool_dir}"
+        curl --fail --location --silent --show-error \
+          https://github.com/EmbarkStudios/cargo-deny/releases/download/0.20.2/cargo-deny-0.20.2-x86_64-unknown-linux-musl.tar.gz \
+          --output "${tool_dir}/cargo-deny.tar.gz"
+        echo "9f12ed4c49936e09b48bf862b595cde2fe64fcbd9d74dfacac6131ca824c8d5f  ${tool_dir}/cargo-deny.tar.gz" | sha256sum --check -
+        tar -xzf "${tool_dir}/cargo-deny.tar.gz" --strip-components=1 -C "${tool_dir}"
+        echo "${tool_dir}" >> "${GITHUB_PATH}"
+    - name: Check threshold dependency policy
+      run: cargo deny --manifest-path tinycloud-threshold/Cargo.toml --locked --config tinycloud-threshold/deny.toml check licenses bans advisories sources
+    - uses: oven-sh/setup-bun@v2
+      with:
+        bun-version: "1.4.4"
+    - name: Run the independent primitive checker
+      working-directory: tinycloud-threshold/vectors/check
+      run: bun install --frozen-lockfile && bun run check
+
   build:
     name: build (workspace)
     runs-on: ubuntu-latest

Cargo.toml

@@ -8,6 +8,7 @@ members = [
     "tinycloud-verifier-wasm",
     "tinycloud-sdk-rs",
     "tinycloud-core",
+    "tinycloud-threshold",
     "dependencies/siwe",
     "dependencies/siwe-recap",
     "dependencies/cacao",

Dockerfile

@@ -16,6 +16,7 @@ COPY ./rust-toolchain.toml ./
 COPY ./tinycloud-node-server/ ./tinycloud-node-server/
 COPY ./tinycloud-auth/ ./tinycloud-auth/
 COPY ./tinycloud-core/ ./tinycloud-core/
+COPY ./tinycloud-threshold/ ./tinycloud-threshold/
 COPY ./tinycloud-sdk-rs/ ./tinycloud-sdk-rs/
 COPY ./tinycloud-sdk-wasm/ ./tinycloud-sdk-wasm/
 COPY ./tinycloud-verifier-wasm/ ./tinycloud-verifier-wasm/

release-plz.toml

@@ -95,3 +95,8 @@ publish = false
 name = "cacaos"
 release = false
 publish = false
+
+[[package]]
+name = "tinycloud-threshold"
+release = false
+publish = false

tinycloud-threshold/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "tinycloud-threshold"
+version = "0.1.0"
+edition = "2021"
+rust-version = "1.97.1"
+license-file = "../LICENSE.md"
+publish = false
+description = "Context-bound threshold key derivation and identity-based key wrapping"
+
+[dependencies]
+blst = "=0.3.16"
+sha2 = "0.10"
+zeroize = { version = "1.8", features = ["derive"] }
+subtle = "2.6"
+rand_core = "0.6"
+thiserror = "2"
+
+[dev-dependencies]
+proptest = "1.6"
+rand_chacha = "0.3"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+hex = "0.4"

tinycloud-threshold/README.md

@@ -0,0 +1,50 @@
+# tinycloud-threshold
+
+BLS12-381 identity-based wrapping of 32-byte data keys and context-bound encrypted threshold key derivation.
+
+The crate is a workspace member with `publish = false`. No other workspace crate depends on it; the node server remains the default member. Release-plz neither releases nor publishes it.
+
+## S0.1 surface
+
+- Bounded, canonical scalar, point, identity, ciphertext, request and share encodings.
+- Boneh–Franklin FullIdent wrapping and unwrapping with the TinyCloud domains in [SPEC.md](SPEC.md).
+- Capability-asserted derivation requests, individual member-share verification, lowest-index threshold interpolation and reader unmasking.
+- Keys retain their identity and certificate/generation context. Shares carry both the key-context digest and the request digest.
+- The blst FFI boundary is confined to `src/curve.rs`; its header inventories the entry points and buffer invariants.
+
+`KeyContext`, `PublicKeySet` and `KeyShare` have no public S0.1 constructor. The dealer exists only under `#[cfg(test)]`. Certificate, ceremony, storage and node-runtime paths are outside this slice. Their protocol contracts are recorded in SPEC.md §§3.7–3.12.
+
+The §3.6 request-digest amendment is explicit in SPEC.md. It makes an identity or transport-key transplant a context mismatch before share equations are evaluated.
+
+## Checks
+
+Use the workspace's pinned Rust 1.97.1 toolchain:
+
+```sh
+cargo test --locked -p tinycloud-threshold
+cargo test -p tinycloud-threshold checkpoint_2of3 -- --nocapture
+cargo clippy -p tinycloud-threshold --all-targets -- -D warnings
+cargo fmt --all -- --check
+PROPTEST_CASES=1024 cargo test --locked -p tinycloud-threshold --release
+cargo deny --manifest-path tinycloud-threshold/Cargo.toml --locked --config tinycloud-threshold/deny.toml check licenses bans advisories sources
+```
+
+The `threshold` job in `.github/workflows/rust.yml` runs the full release suite, the explicitly selected cargo-deny policy and the independent primitive checker. Workspace test, build, formatting and clippy jobs also include this member.
+
+The checkpoint prints nine executed outcomes. Required RFC tests are separately named `rfc9380_appendix_j_g1_sswu_ro`, `rfc9380_appendix_j_g2_sswu_ro` and `rfc9380_appendix_k1_expand_xmd_sha256`.
+
+## Vectors
+
+`vectors/v1/primitives.json` records fixed test seeds and test scalars, frozen domains, hash/group/pairing bytes, FullIdent inputs and outputs, a 2-of-3 derivation and named error cases. These are public test values, not deployment keys. `primitive_vectors_regenerate_byte_for_byte` regenerates the file in memory and compares its complete bytes. To update it deliberately:
+
+```sh
+TC_THRESHOLD_REGEN_VECTORS=1 cargo test -p tinycloud-threshold primitive_vectors_regenerate_byte_for_byte
+```
+
+`rfc9380-{g1,g2,k1}.json` contains the published Appendix J.9.1, J.10.1 and K.1 cases. The separate-session checker consumes SPEC.md and the JSON vector format, without consulting the Rust implementation. Its CI entry point is `bun install --frozen-lockfile && bun run check` in `vectors/check/`.
+
+## Dependencies and licence
+
+This crate uses the workspace's [TinyCloud EGPL v1.5](../LICENSE.md) through `license-file`. Production dependencies: `blst` (Apache-2.0), `sha2` (MIT OR Apache-2.0), `zeroize` (Apache-2.0 OR MIT), `subtle` (BSD-3-Clause), `rand_core` (MIT OR Apache-2.0), and `thiserror` (MIT OR Apache-2.0). Development dependencies: `proptest`, `rand_chacha`, `serde`, `serde_json`, and `hex` (MIT OR Apache-2.0).
+
+The crate-scoped `deny.toml` includes development and build dependencies. It allows Apache-2.0, MIT, BSD-3-Clause, ISC and Unicode-3.0, with a hash-pinned EGPL clarification and exception for this crate only. Registry sources are restricted to crates.io.