ddn.net.dtls.session

DTLS 1.3 session resumption and 0-RTT early data (RFC 9147 §8).

Implements session ticket management for DTLS 1.3 session resumption. After a successful handshake, the server issues a NewSessionTicket containing an encrypted PSK that the client can use to resume the session in a subsequent connection.

Key components:

  • DtlsSessionTicket: Ticket encryption/decryption using AES-GCM
  • DtlsReplayCache: Anti-replay protection for 0-RTT early data
  • DtlsSessionStore: Client-side session ticket storage
struct DtlsEncryptedTicket
class DtlsReplayCache DtlsSessionStore DtlsTicketKeyManager

Types 4

structDtlsEncryptedTicket

Encrypted session ticket for DTLS 1.3 resumption.

The ticket contains:

  • Encrypted PSK and metadata (encrypted with server's ticket key)
  • Ticket nonce (for key derivation)
  • Lifetime and early data limits
Fields
ubyte[] nonce
ubyte[] ciphertext
uint lifetimeSeconds
size_t maxEarlyDataSize
ushort cipherSuite
classDtlsTicketKeyManager

Session ticket encryption key manager.

Server-side component that manages ticket encryption keys. Keys are rotated periodically for forward secrecy.

Fields
SecureRandom rng_
ubyte[][32] keys_
size_t activeKeyIndex_
Duration keyRotationInterval_
MonoTime lastRotation_
size_t keyCount_
Methods
void rotateKey()Rotates to a new ticket encryption key.
ubyte[] activeKey()Returns: the active encryption key.
DtlsEncryptedTicket encryptTicket(const(ubyte)[] psk, ushort cipherSuite, uint lifetimeSeconds, size_t maxEarlyData)Encrypts session data into a ticket.
auto decryptTicket(DtlsEncryptedTicket ticket)Decrypts a session ticket.
Constructors
this(SecureRandom rng, Duration rotationInterval = dur!"hours"(1))Constructs a ticket key manager.
classDtlsReplayCache

Anti-replay cache for 0-RTT early data.

Tracks seen session tickets to prevent replay attacks. Supports multiple strategies as defined by EarlyDataReplayProtection.

Fields
EarlyDataReplayProtection mode_
Duration timeWindow_
ubyte[][32] seenTickets_
MonoTime[32] seenTimes_
size_t seenCount_
size_t nextSlot_
Methods
bool checkAndRecord(const(ubyte)[] ticket)Checks if a ticket has been seen (replay check).
void prune()Prunes expired entries (for TIME_WINDOWED mode).
Constructors
this(EarlyDataReplayProtection mode = EarlyDataReplayProtection.SINGLE_USE_TICKETS, Duration timeWindow = dur!"seconds"(DtlsSessionConstants.DEFAULT_EARLY_DATA_WINDOW_S))Constructs a replay cache.
classDtlsSessionStore

Client-side session store.

Stores session tickets received from servers for later resumption. Supports multiple server endpoints with at most one active session per endpoint.

Fields
DtlsSessionInfo[DatagramEndpoint] sessions_
Duration maxSessionAge_
Methods
void store(scope ref const DtlsSessionInfo session)Stores a session ticket.
DtlsSessionInfo * get(DatagramEndpoint serverAddr)Retrieves a session for the given server.
void remove(DatagramEndpoint serverAddr)Removes a stored session.
size_t count() @property const @safe pure nothrow @nogcReturns: the number of stored sessions.
void prune()Removes all expired sessions.
Constructors
this(Duration maxSessionAge = dur!"hours"(24))Constructs a session store.