Struct CryptoSession 

pub struct CryptoSession { /* private fields */ }

Available on crate feature crypto only.

A complete crypto session for secure communication.

Combines key management, nonce construction, AEAD, and anti-replay into a single interface.

Implementations

impl CryptoSession

pub fn new( session_id: SessionId, role: Role, send_key: SessionKey, recv_key: SessionKey, handshake_hash: [u8; 32], rekey_auth_key: [u8; 32], ) -> Self

Create a new crypto session after handshake completion.

Arguments

• session_id - Unique session identifier
• role - Our role (initiator or responder)
• send_key - Initial send key
• recv_key - Initial receive key
• handshake_hash - Hash of the handshake transcript
• rekey_auth_key - Key derived from static DH for PCS during rekey

pub fn session_id(&self) -> &SessionId

Get the session ID.

pub fn role(&self) -> Role

Get the current role.

pub fn epoch(&self) -> u32

Get the current epoch.

pub fn should_rekey(&self) -> bool

Check if we should initiate a rekey.

pub fn keys_expired(&self) -> bool

Check if keys are expired (session must terminate).

pub fn encrypt_frame( &mut self, frame_type: u8, flags: u8, plaintext: &[u8], ) -> Result<(u64, Vec<u8>), CryptoError>

Encrypt a frame for sending.

Returns (nonce_counter, ciphertext).

pub fn decrypt_frame( &mut self, frame_type: u8, flags: u8, nonce_counter: u64, ciphertext: &[u8], ) -> Result<Vec<u8>, CryptoError>

Decrypt a received frame.

Performs replay check BEFORE decryption per spec.

pub fn rekey(&mut self, ephemeral_dh: &[u8; 32]) -> Result<(), CryptoError>

Perform a rekey operation with the given ephemeral DH result.

Advances the epoch and derives new keys using PCS-secure derivation. The caller is responsible for performing the ephemeral key exchange and computing the DH shared secret.

Arguments

• ephemeral_dh - The result of DH(my_ephemeral, their_ephemeral_public)

Security

The rekey_auth_key (derived from static DH during handshake) is mixed into the KDF along with ephemeral_dh. This ensures:

• Forward secrecy from the fresh ephemeral exchange
• Post-compromise security from the static DH-derived auth key