Module crypto 

Available on crate feature crypto only.

NOMAD Protocol - Security Layer

Implements the cryptographic primitives for NOMAD:

• Noise_IK handshake
• XChaCha20-Poly1305 AEAD
• Nonce construction
• Anti-replay protection
• Rekeying

Structs

CryptoSession

A complete crypto session for secure communication.

HandshakeResult

Result of a completed handshake

InitiatorHandshake

Handshake state machine for the initiator (client).

OldKeyRetention

Manages old keys during the transition period after a rekey.

RekeyState

Tracks the current key epoch and when rekeying is needed.

ReplayWindow

Anti-replay sliding window.

ResponderHandshake

Handshake state machine for the responder (server).

SessionId

Session ID - 48-bit random identifier for session demultiplexing.

SessionKey

A session key for AEAD operations.

SessionKeys

Session keys derived from the Noise handshake.

StaticKeypair

A static X25519 keypair for long-term identity.

Enums

Direction

Direction of communication for nonce construction.

Role

Role in the handshake (affects which key is used for send/receive)

Constants

AAD_SIZE

Size of AAD for data frames (type + flags + session_id + nonce_counter)

SESSION_KEY_SIZE

Size of the session key (32 bytes for XChaCha20)

Functions

construct_aad

Construct AAD (Additional Authenticated Data) for a data frame.

construct_nonce

Construct a 24-byte XChaCha20-Poly1305 nonce.

decrypt

Decrypt ciphertext using XChaCha20-Poly1305.

decrypt_in_place

Decrypt ciphertext in-place, removing the tag.

derive_rekey_auth_key

Derive the rekey authentication key from static DH secret.

derive_rekey_keys

Derive new session keys after a rekey with PCS protection.

encrypt

Encrypt plaintext using XChaCha20-Poly1305.

encrypt_in_place

Encrypt plaintext in-place, appending the tag.

parse_nonce

Parse a nonce back into its components.