Native Layer 1: Zero-copy COSE primitives with streaming parse/sign/verify

[JeromySt]

Native Layer 1 — Primitives

Foundational Rust crates for COSE_Sign1 message handling with a zero-copy, streaming-first architecture.

Architecture

CoseSign1Message owns a single Arc<[u8]> backing buffer. All fields are byte-range slices — no payload/signature copies on parse. Header values use ArcSlice/ArcStr to share the same buffer. LazyHeaderMap defers parsing until first access via OnceLock.

Memory profiles:

Operation	Buffered	Streamed (10GB file)
Parse	1x input + ~700B	~1.4KB
Sign (detached)	~64KB peak	~64KB peak
Verify (ECDSA/RSA)	~64KB peak	~64KB peak
Verify (Ed25519)	1x payload	1x payload (fallback)

Rust Crates (8)

CBOR Layer:

• cbor_primitives — Encoding/decoding traits (CborDecoder, CborStreamDecoder)
• cbor_primitives_everparse — EverParse backend + streaming decoder from Read+Seek

COSE Layer:

• cose_primitives — RFC 9052 types, CoseData (Buffered/Streamed), LazyHeaderMap, ArcSlice/ArcStr
• cose_sign1_primitives — Sign1 message, builder, sig_structure, streaming parse/sign/verify

Crypto Layer:

• crypto_primitives — Signer/verifier traits, JWK types, SigningContext/VerifyingContext
• cose_sign1_crypto_openssl — OpenSSL EC/RSA/EdDSA/ML-DSA provider

FFI Projections:

• cose_sign1_primitives_ffi — C-ABI for Sign1 operations
• cose_sign1_crypto_openssl_ffi — C-ABI for crypto provider

C/C++ Projections

• cose.h / cose.hpp — Shared COSE types
• sign1.h / sign1.hpp — Sign1 primitives
• crypto/openssl.h / crypto/openssl.hpp — Crypto provider

Key Design Decisions

• Single-buffer ownership: CoseData owns the raw bytes; CoseSign1 slices into it
• Streaming CBOR: CborStreamDecoder reads from Read+Seek, skips large payloads by offset
• Single-pass sign+embed: Embedded payloads read once into a shared buffer used for both signing and .Content
• MemoryPayload uses Arc<[u8]>: open() is a pointer copy, not a data clone
• Lazy headers: OnceLock defers BTreeMap allocation until first typed access
• EverParse streaming note: Stream decoder parses manually; headers are re-validated via EverParse on lazy parse

Documentation

• native/rust/docs/memory-characteristics.md — Full memory profiles and scenarios
• native/docs/ARCHITECTURE.md — Layered dependency graph
• Per-crate READMEs, FFI guide, getting started

Quality

• 221+ tests, 90%+ line coverage (collect-coverage-asan.ps1 passes)
• Zero cargo clippy warnings
• cargo fmt clean

[JeromySt]

@copilot can you review the remaining files you didn't already review?

[Copilot]

@JeromySt I've opened a new pull request, #183, to work on those changes. Once the pull request is ready, I'll request review from you.