version 1 .

; https://noiseprotocol.org/

; Assertion.
Connect = <connect @serviceSelector any @initiatorSession #!any> .

; Assertion (to initiatorSession).
Accept = <accept @responderSession #!any> .

; Sessions proceed by sending Packets to the initiatorSession and responderSession according to
; the Noise protocol definition. Each Packet represents a complete logical unit of
; communication; for example, a complete Turn when layering the Syndicate protocol over Noise.
; Note well the restriction on Noise messages: no individual complete packet or packet fragment
; may exceed 65535 bytes (N.B. not 65536!). When `fragmented`, each portion of a Packet is a
; complete Noise "transport message"; when `complete`, the whole thing is likewise a complete
; "transport message".
Packet = @complete bytes / @fragmented [bytes ...] .

; When layering Syndicate protocol over noise,
;
;  - the canonical encoding of the serviceSelector is the prologue
;  - protocol.Packets MUST be encoded using the machine-oriented Preserves syntax
;  - zero or more Turns are permitted per noise.Packet
;  - each Turn must fit inside a single noise.Packet (fragment if needed)
;  - payloads inside a noise.Packet may be padded at the end with byte 0x80 (128), which
;    encodes `#f` in the machine-oriented Preserves syntax.
;
; In summary, each noise.Packet, once (reassembled and) decrypted, will be a sequence of zero
; or more machine-encoded protocol.Packets, followed by zero or more 0x80 bytes.

; A `Route` describes a network path that can be followed to reach some target entity.
;
; It starts with zero or more possible non-Syndicate `transports`, in preference order. These
; could be `transportAddress.Tcp` values or similar. They are just suggestions; it's quite
; possible the endpoint is reachable by some means not listed. The network outside Syndicate
; is, after all, pretty diverse! In particular, *zero* `transports` may be provided, in which
; case some out-of-band means has to be used to make that first connection.
;
; The `transports` give instructions for contacting the first entity in the `Route` path. Often
; this will be a `gatekeeper`, or a `noise` protocol endpoint, or both. Occasionally, it may
; even be the desired target entity. Subsequent `steps` describe how to proceed from the
; initial entity to the target.
Route = <route @transports [any ...] @steps RouteStep ...> .
RouteStep = NoiseStep / GatekeeperStep .

GatekeeperStep = sturdy.SturdyRef .

NoiseStep = <noise @spec NoiseSpec> .
NoiseSpec = {
  ; The `serviceSelector` to use in a `Connect`.
  service: any,
  ; The responder's static public key. If not required (uncommon!), supply the empty ByteString.
  key: bytes,
}
& @protocol NoiseProtocol
& @preSharedKeys NoisePreSharedKeys
.

; If absent, a default of DefaultProtocol is used. Most services will speak the default.
NoiseProtocol = @present { protocol: string } / @invalid { protocol: any } / @absent {} .
DefaultProtocol = "Noise_NK_25519_ChaChaPoly_BLAKE2s" .

; If present, Noise pre-shared-keys (PSKs) are drawn from the sequence as required; if the
; sequence is exhausted or not supplied, an all-zeros key is used each time a PSK is needed.
NoisePreSharedKeys = @present { preSharedKeys: [bytes ...] } / @invalid { preSharedKeys: any } / @absent {} .