drop tunnels (#165)

Fix #163

Signed-off-by: Thomas Fossati <[email protected]>

cddl/cmw-collection.cddl

@@ -1,9 +1,9 @@
 json-collection = {
   ? "__cmwc_t": ~uri / oid
-  + &(label: text) => json-cmw / c2j-tunnel
+  + &(label: text) => json-cmw
 }
 
 cbor-collection = {
   ? "__cmwc_t": ~uri / oid
-  + &(label: (int / text)) => cbor-cmw / j2c-tunnel
+  + &(label: (int / text)) => cbor-cmw
 }

cddl/collection-example-2.diag

@@ -7,7 +7,8 @@
   ],
   / attester B / 1: 1668576935(h'2347da55'),
   / attester C / 2: [
-    "#cmw-j2c-tunnel",
-    '[ "application/eat+jwt", "Li4u", 8 ]'
+    "application/eat+jwt",
+    h'2e2e2e',
+    8
   ]
 }

cddl/collection-example-2.json

@@ -5,8 +5,9 @@
     "e30K",
     4
   ],
-  "attester B (tunnelled)": [
-    "#cmw-c2j-tunnel",
-    "g3gYYXBwbGljYXRpb24vZWF0LXVjcytjYm9yQaAE"
+  "attester B": [
+    "application/eat-ucs+cbor",
+    "oA",
+    4
   ]
 }

cddl/eat-example-1.json

@@ -6,9 +6,10 @@
       "e30K",
       4
     ],
-    "attester B (tunnelled)": [
-      "#cmw-c2j-tunnel",
-      "g3gYYXBwbGljYXRpb24vZWF0LXVjcytjYm9yQaAE"
+    "attester B": [
+      "application/eat-ucs+cbor",
+      "oA",
+      4
     ]
   },
   "iss": "evidence collection daemon",

cddl/frags.mk

@@ -2,7 +2,6 @@ CMW_FRAGS := cmw-start.cddl
 CMW_FRAGS += cmw-record.cddl
 CMW_FRAGS += cmw-cbor-tag.cddl
 CMW_FRAGS += cmw-collection.cddl
-CMW_FRAGS += cmw-tunnel.cddl
 CMW_FRAGS += common-types.cddl
 CMW_FRAGS += rfc9193.cddl
 # CBOR tags used in examples
@@ -25,7 +24,6 @@ EAT_FRAGS := eat-start.cddl
 EAT_FRAGS += cmw-start.cddl
 EAT_FRAGS += cmw-record.cddl
 EAT_FRAGS += cmw-collection.cddl
-EAT_FRAGS += cmw-tunnel.cddl
 EAT_FRAGS += common-types.cddl
 EAT_FRAGS += rfc9193.cddl
 
@@ -35,6 +33,5 @@ COLLECTED_CDDL_FRAGS := cmw-start.cddl
 COLLECTED_CDDL_FRAGS += cmw-record.cddl
 COLLECTED_CDDL_FRAGS += cmw-cbor-tag.cddl
 COLLECTED_CDDL_FRAGS += cmw-collection.cddl
-COLLECTED_CDDL_FRAGS += cmw-tunnel.cddl
 COLLECTED_CDDL_FRAGS += common-types.cddl
 COLLECTED_CDDL_FRAGS += rfc9193.cddl

draft-ietf-rats-msg-wrap.md

@@ -165,16 +165,9 @@ This document reuses the terms defined in {{Section 2 of -senml-cf}}
 
 # Conceptual Message Wrappers
 
-A RATS Conceptual Message Wrapper (CMW) has a tree structure of leaves that contain payload messages associated with their content type.
-The two leaf node types are:
-
-* A CMW using a CBOR or JSON record ({{type-n-val}});
-* A CMW based on CBOR tags ({{cbor-tag}}).
-
-Intermediate tree nodes are either:
-
-* A CMW "collection" type that holds together multiple CMW items ({{cmw-coll}});
-* A CMW "tunnel" type that allows transporting CBOR CMWs in JSON collections and vice-versa ({{cmw-tunnel}}).
+A RATS Conceptual Message Wrapper (CMW) has a tree structure.
+Leaf nodes are of type "record" ({{type-n-val}}), or "CBOR tag" ({{cbor-tag}}).
+Intermediate nodes are of type "collection" ({{cmw-coll}}; they hold together multiple CMW items.
 
 The following snippet outlines the productions associated with the top-level types.
 
@@ -268,7 +261,7 @@ Although originally designed to support layered Attester and composite device us
 For instance, collections may be used to group Endorsements, Reference Values, Attestation Results, and more.
 A single CMW collection can contain a mix of different message types, and it can also be used to carry messages related to multiple devices simultaneously.
 
-The CMW collection ({{fig-cddl-collection}}) is defined as a CBOR map or JSON object with CMW values, either native or "tunnelled" ({{cmw-tunnel}}).
+The CMW collection ({{fig-cddl-collection}}) is defined as a CBOR map or JSON object containing CMW values.
 The position of a `cmw` entry in the `cmw-collection` is not significant.
 Labels can be strings (or integers in the CBOR serialization) that serve as a mnemonic for different conceptual messages in the collection.
 
@@ -301,34 +294,6 @@ A CMW Collection's tree structure is not required to be a spanning tree of the s
 If the labels carry semantic content for a Verifier (e.g. to improve Verifier performance or aid human comprehension), the collection SHOULD be integrity protected.
 For example, the collection can be integrity protected by including it in a signed token such as a CWT or JWT.
 
-### CMW Tunnel {#cmw-tunnel}
-
-The CMW tunnel type ({{fig-cddl-tunnel}}) allows for moving a CMW in one serialization format, either JSON or CBOR, into a collection that uses the opposite serialization format.
-
-Both tunnel types are arrays with two elements.
-The first element, a fixed text string starting with a `#`, acts as a sentinel value.
-The `#`, which is not an acceptable start symbol for the `Content-Type` production ({{collected-cddl}}), makes it possible to disambiguate a CMW tunnel from a CMW record.
-
-~~~ cddl
-{::include cddl/cmw-tunnel.cddl}
-~~~
-{: #fig-cddl-tunnel artwork-align="left"
-   title="CDDL definition of the CMW tunnel format"}
-
-The conversion algorithms are described in the following subsections.
-
-#### CBOR-to-JSON
-
-The CBOR byte string of the serialised CBOR CMW is encoded as Base64 using the URL and filename safe alphabet ({{Section 5 of -base64}}) without padding.
-The obtained string is added as the second element of the `c2j-tunnel` array.
-The `c2j-tunnel` array is serialized as JSON.
-
-#### JSON-to-CBOR
-
-The UTF-8 string of the serialized JSON CMW is encoded as a CBOR byte string (Major type 2).
-The byte string is added as the second element of the `j2c-tunnel` array.
-The `j2c-tunnel` array is serialized as CBOR.
-
 ## Decapsulation Algorithm
 
 Once any external framing is removed (for example, if the CMW is carried in a certificate extension), the CMW decoder performs a 1-byte lookahead to determine how to decode the remaining byte buffer.
@@ -450,7 +415,7 @@ END
 
 Section 6.1.8 of {{DICE-arch}} specifies the ConceptualMessageWrapper (CMW) format and its corresponding object identifier.
 The CMW format outlined in {{DICE-arch}} permits only a subset of the CMW grammar defined in this document.
-In particular, the tunnel and collection formats cannot be encoded using DICE CMWs.
+In particular, the collection format cannot be encoded using DICE CMWs.
 
 # Examples
 
@@ -527,7 +492,6 @@ lication/signed-corim+cbor"
 ## CBOR Collection
 
 The following example is a CBOR collection that assembles conceptual messages from three attesters: Evidence for attesters A and B and Attestation Results for attester C.
-Since attester C returns Attestation Results as CMW in JSON record format, the JSON record needs to be tunnelled.
 It is given an explicit collection type using the URI form.
 
 ~~~
@@ -537,7 +501,6 @@ It is given an explicit collection type using the URI form.
 ## JSON Collection
 
 The following example is a JSON collection that assembles Evidence from two attesters.
-Since attester B outputs Evidence as CMW in CMW record format, the CBOR record needs to be tunnelled.
 
 ~~~
 {::include cddl/collection-example-2.json}