ristretto255

1. Route

1. CLASSIFY: library integration | protocol design/review | abstraction implementation/audit.
2. Normative: RFC 9496; rationale: ristretto.group; check errata.
3. Protocol underspecified scalar derivation/hash-to-group/identity/transcript/KDF => STOP.
4. Library selection -> READ references/libraries.md.
5. Internals -> READ references/implementation.md.
6. Protocol/hash/transcript/shared element -> READ references/protocol-use.md.

2. Implementation choice

PREFER maintained dedicated API. VERIFY version, maintenance, strict decode, canonical scalar parse, wide reduction, CT secret multiplication, 64-byte map, RFC vectors. From-scratch only if project owns CT Curve25519 field + complete Edwards ops AND required platform/interoperability excludes libraries.

3. Type boundary