Module case 

Matter CASE (Certificate Authenticated Session Establishment) via SIGMA-I.

Implementation lands across phases:

• M4.1 (current): math + Sigma1/2/3 state machines + new-session wire messages.
• M4.2: session resumption (Sigma2_Resume, Sigma3_Resume).
• M4.3: matter.js byte-parity verification + readiness markers.

See Matter Core Specification §4.13 and docs/superpowers/specs/2026-05-19-matter-crypto-case-design.md.

Structs

CaseCredentials

Operational identity for a CASE session.

CaseSessionKeys

Symmetric session keys derived by a completed CASE handshake.

CaseSessionOutput

Output of a successful CASE handshake.

LocalInfo

Our own identity on the session (mirror of PeerInfo, useful for symmetry).

PeerInfo

Identity of the peer we just shook hands with.

ResumptionId

16-byte resumption identifier.

ResumptionRecord

State persisted by the caller after a successful CASE handshake, allowing a future session to skip the full 3-message handshake via Sigma2_Resume. Resumption flow lands in M4.2.

Enums

CaseMessageKind

Identifies one of the 5 CASE message types. Used by crate::Error::UnexpectedMessage and expected_inbound() accessors on the state machines.

Sigma1Outcome

Outcome of processing a Sigma1 message.