@spec build_tbs(binary(), binary() | nil, binary(), binary()) :: binary()

Build TBS (to-be-signed) data as a TLV structure.

Matter CASE TBS contains:

• Tag 1: Sender NOC certificate
• Tag 2: Sender ICAC certificate (optional)
• Tag 3: Sender ephemeral public key (65 bytes)
• Tag 4: Receiver ephemeral public key (65 bytes)

@spec compute_destination_id(
  binary(),
  binary(),
  binary(),
  non_neg_integer(),
  non_neg_integer()
) ::
  binary()

Compute CASE destination identifier.

dest_id = HMAC-SHA256(IPK, initiator_random || root_public_key || fabric_id_le64 || node_id_le64)

The root_public_key is the full 65-byte uncompressed EC point (including 0x04 prefix).

@spec decode_noc(binary()) :: {:ok, map()} | {:error, :invalid_message}

Decode a NOC. Accepts both X.509 DER certificates (as sent by chip-tool) and the simplified TLV format used in internal tests.

@spec decrypt_tbe(:sigma2 | :sigma3, binary(), binary()) :: {:ok, binary()} | :error

Decrypt TBE data with AES-128-CCM.

@spec default_session_parameters() :: map()

Default secure-channel session parameters.

These mirror the fields emitted by connectedhomeip's PairingSession EncodeSessionParameters: MRP timings plus protocol revision hints.

@spec derive_sigma2_key(binary(), binary(), binary(), binary(), binary()) :: binary()

Derive S2K key for Sigma2 TBE encryption.

Salt = IPK(16) || responder_random(32) || responder_eph_pub(65) || transcript_hash(32) = 145 bytes. The transcript_hash is SHA256 of sigma1 payload only.

@spec derive_sigma3_key(binary(), binary(), binary()) :: binary()

Derive S3K key for Sigma3 TBE encryption.

Salt = IPK(16) || transcript_hash(32) = 48 bytes. The transcript_hash is SHA256 of sigma1 || sigma2 payloads.

@spec encode_noc(non_neg_integer(), non_neg_integer(), binary()) :: binary()

Encode a simplified NOC containing node_id, fabric_id, and public_key.

@spec encrypt_tbe(:sigma2 | :sigma3, binary(), binary()) :: binary()

Encrypt TBE data with AES-128-CCM. Returns ciphertext <> tag.

@spec extract_public_key(binary()) :: binary() | nil

Extract the public key from an X.509 DER certificate.

Returns the raw EC point (65 bytes for P-256 uncompressed) or nil. Works with any X.509 cert (root CA, ICAC, or NOC).