4.1.0

Add DTLSContext and DTLS for datagram TLS

DTLSContext and DTLS bring DTLS (datagram TLS) support. DTLS provides the same authentication and encryption as TLS over unreliable transports like UDP.

The API mirrors SSLContext and SSL. A DTLSContext creates client or server DTLS sessions; the session encrypts and decrypts application data through write, read, receive, and send, with the same return types (SSLReceiveResult, SSLReadResult).

let ctx = recover val
  let c = DTLSContext
  c.set_cert(
    FilePath(auth, "cert.pem"),
    FilePath(auth, "key.pem"))?
  c.set_authority(FilePath(auth, "ca.pem"))?
  c.set_client_verify(true)
  c
end

let session = ctx.client("server.example.com")?

// Feed encrypted bytes from the network into the session
match session.receive(data_from_udp)
| SSLReady => None // handshake complete
| SSLAccepted => None // still handshaking
| SSLAuthFail => // peer certificate rejected
| SSLError => // protocol error
end

// Encrypt application data for sending
session.write("hello")?
match session.send()
| let out: Array[U8] iso => send_over_udp(consume out)
end

// Read decrypted application data
match session.read()
| let plaintext: Array[U8] iso => // use it
end

DTLSContext and SSLContext are separate types because a TLS context cannot create a DTLS session and vice versa. Using separate types makes the wrong combination a compile error.

[4.1.0] - 2026-08-07

Added

• Add DTLSContext and DTLS for datagram TLS (PR #153)