[Cbor] CDDL degenericizer (cddlc tool 0.1.0 update)

[Carsten Bormann <[e-mail]>]

Tool builders often want to process as minimal a subset of CDDL as possible.
One slight complication that not every tool builder wants to handle is processing the generics feature.

As the cddlc (note the “c” at the end) tool is gaining CDDL 2.0 functionality, I’m pushing out revisions that already do something useful; today’s release doesn’t add in actual CDDL 2.0 features yet, though.

cddlc version 0.1.0 now supports (all these require or imply the -r option):

— writing “processed” CDDL, using the -tcddl option
— expanding all generics, using the -x option.
— complaining about undefined rule names, using the -u option.

I have attached the output of

    cddlc -urxtcddl uccs.cddl

if you want to see how this works.
The point of course is not to use “processed” CDDL to obtain working copies for humans, but to feed this into tools such as validators or code generators.

As always:

    gem update cddlc

Note: A recent version of Ruby (3.x) is required to activate these additional features.

Bug reports are gladly accepted, as github issues [1], email, etc.
(I already know that any attempt at indentation is out of whack; maybe I shouldn’t try that…)

(Next: CDDL 2.0 import features.)

Grüße, Carsten

[1]: https://github.com/cabo/cddlc


*** uccs.cddl:

Claims-Set = {
 * $$Claims-Set-Claims
 * Claim-Label .feature "extended-claims-label" => any
}
Claim-Label = CBOR-ONLY<int> / text
string-or-uri = text

$$Claims-Set-Claims //= ( iss-claim-label => string-or-uri  )
$$Claims-Set-Claims //= ( sub-claim-label => string-or-uri  )
$$Claims-Set-Claims //= ( aud-claim-label => string-or-uri  )
$$Claims-Set-Claims //= ( exp-claim-label => ~time )
$$Claims-Set-Claims //= ( nbf-claim-label => ~time )
$$Claims-Set-Claims //= ( iat-claim-label => ~time )
$$Claims-Set-Claims //= ( cti-claim-label => bytes )

iss-claim-label = JC<"iss", 1>
sub-claim-label = JC<"sub", 2>
aud-claim-label = JC<"aud", 3>
exp-claim-label = JC<"exp", 4>
nbf-claim-label = JC<"nbf", 5>
iat-claim-label = JC<"iat", 6>
cti-claim-label = CBOR-ONLY<7>  ; jti in JWT: different name and text

JSON-ONLY<J> = J .feature "json"
CBOR-ONLY<C> = C .feature "cbor"
JC<J,C> = JSON-ONLY<J> / CBOR-ONLY<C>


; [RFC8747]
$$Claims-Set-Claims //= ( 8: CWT-cnf ) ; cnf
CWT-cnf = {
  (1: CWT-COSE-Key) //
  (2: CWT-Encrypted_COSE_Key) //
  (3: CWT-kid)
}

CWT-COSE-Key = COSE_Key
CWT-Encrypted_COSE_Key = COSE_Encrypt / COSE_Encrypt0
CWT-kid = bytes

; [RFC8693]
$$Claims-Set-Claims //= ( 9: CWT-scope ) ; scope
; TO DO: understand what this means:
; scope The scope of an access token as defined in [RFC6749].
; scope 9 byte string or text string [IESG] [RFC8693, Section 4.2]
CWT-scope = bytes / text

; [RFC-ietf-ace-oauth-authz-45, Section 5.10]
$$Claims-Set-Claims //= ( 38: CWT-ace-profile ) ; ace_profile
CWT-ace-profile = $CWT-ACE-Profiles /
  int .feature "ace_profile-extend"
; fill in from IANA registry
;   https://www.iana.org/assignments/ace/ace.xhtml#ace-profiles :
$CWT-ACE-Profiles /= 1 ; coap_dtls

$$Claims-Set-Claims //= ( 39: CWT-cnonce ) ; cnonce
CWT-cnonce = bytes

$$Claims-Set-Claims //= ( 40: CWT-exi ) ; exi
CWT-exi = uint ; in seconds (5.10.3)

;;; insert CDDL from 9052-to-be to complete these CDDL definitions.



*** Output of cddlc -urxtcddl uccs.cddl:

;;; *** undefined: COSE_Key
;;; *** undefined: COSE_Encrypt
;;; *** undefined: COSE_Encrypt0
Claims-Set = {
  * $$Claims-Set-Claims,
  * Claim-Label .feature "extended-claims-label" => any,
}
Claim-Label = int .feature "cbor" / text
string-or-uri = text
$$Claims-Set-Claims = (iss-claim-label => string-or-uri // sub-claim-label => string-or-uri // aud-claim-label => string-or-uri // exp-claim-label => ~time // nbf-claim-label => ~time // iat-claim-label => ~time // cti-claim-label => bytes // 8 => CWT-cnf // 9 => CWT-scope // 38 => CWT-ace-profile // 39 => CWT-cnonce // 40 => CWT-exi)
iss-claim-label = "iss" .feature "json" / 1 .feature "cbor"
sub-claim-label = "sub" .feature "json" / 2 .feature "cbor"
aud-claim-label = "aud" .feature "json" / 3 .feature "cbor"
exp-claim-label = "exp" .feature "json" / 4 .feature "cbor"
nbf-claim-label = "nbf" .feature "json" / 5 .feature "cbor"
iat-claim-label = "iat" .feature "json" / 6 .feature "cbor"
cti-claim-label = 7 .feature "cbor"
CWT-cnf = {1 => CWT-COSE-Key // 2 => CWT-Encrypted_COSE_Key // 3 => CWT-kid}
CWT-COSE-Key = COSE_Key
CWT-Encrypted_COSE_Key = COSE_Encrypt / COSE_Encrypt0
CWT-kid = bytes
CWT-scope = bytes / text
CWT-ace-profile = $CWT-ACE-Profiles / int .feature "ace_profile-extend"
$CWT-ACE-Profiles = 1
CWT-cnonce = bytes
CWT-exi = uint