45 lines
2.9 KiB
TOML
45 lines
2.9 KiB
TOML
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# KEY-05 layer (b) — the crate-wide compile-time ban on defaulted RNG entry points.
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#
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# WHY THIS FILE EXISTS
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# `rand::random()` and `rand::thread_rng()` are not broken today: on the pinned
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# `rand 0.8.5` both resolve to a ChaCha12 CSPRNG seeded from `getrandom(2)`.
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# What they lack is a STATED entropy backend. The backend is fixed by dependency
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# and build configuration rather than by the calling code, and nothing produces a
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# compile error if that changes underneath us. That is the exact structural shape
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# ("T1") behind the 2026-07-30 COLDCARD entropy defect — and here the blast radius
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# includes Cashu blinded-key-exchange values, X3DH prekey material, session bearer
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# tokens and a ChaCha20-Poly1305 nonce.
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#
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# So every draw must name `rand::rngs::OsRng` at its own call site, and key
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# material and AEAD nonces must additionally run the degenerate-entropy predicate
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# in `archipelago::entropy`.
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#
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# HOW IT IS ENFORCED
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# No CI change was needed for this layer. The existing Rust job already runs
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# `cargo clippy --all-targets --all-features -- -D warnings` from `core/`, so a
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# `disallowed_methods` hit is already a build failure. `--all-targets` means test
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# code is covered too, which is deliberate: test fixtures migrate to `OsRng` as
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# readily as production code does, and a fixture that keeps the default is a
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# template for the next production call site.
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#
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# SCOPE, STATED HONESTLY
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# This reaches the five workspace members (archipelago, archipelago-container,
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# archipelago-openwrt, archipelago-performance, archipelago-security), verified
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# via `cargo metadata --no-deps`. It does NOT reach `core/models`, which is not a
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# workspace member and therefore not in the clippy build graph; the two matches
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# there are recorded as a stated limitation in the evidence document.
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#
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# IF YOU ARE HITTING THIS LINT
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# Do not add `#[allow]` reflexively. Use `rand::rngs::OsRng` at the call site. If
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# the value is key material or an AEAD nonce of at least 12 bytes, route it through
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# `crate::entropy::draw_key_bytes`. An `#[allow(clippy::disallowed_methods)]` needs a
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# justification comment on the line above stating why the DEFAULT is required here —
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# "it is a test" is not a justification.
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#
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# See: docs/security/KEY-05-ENTROPY-ENFORCEMENT.md
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disallowed-methods = [
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{ path = "rand::random", reason = "KEY-05: inherits its entropy backend from a dependency default instead of stating it. Use rand::rngs::OsRng at the call site; for key material or AEAD nonces >= 12 bytes use crate::entropy::draw_key_bytes. See docs/security/KEY-05-ENTROPY-ENFORCEMENT.md" },
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{ path = "rand::thread_rng", reason = "KEY-05: inherits its entropy backend from a dependency default instead of stating it. Use rand::rngs::OsRng at the call site; for key material or AEAD nonces >= 12 bytes use crate::entropy::draw_key_bytes. See docs/security/KEY-05-ENTROPY-ENFORCEMENT.md" },
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]
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