ucan-recap.md

Exploreing the differences between how capabilities are represetned between UCAN and ReCap.

Comparison

	UCAN	ReCap
$RESOURSE	Needs to be a URI	Any String
$ABILITY	One ability per resource ref	Any nymber of abilities per resource ref
$EXTENSION	Additional caveats for a specific resource	Additional information, relevant for all resources
All resources	Not possible	In def property
OCAP delegation	In prf property (not within capability)	Possibly in ext property
namespace	Defined as part of $ABILITY	Defined, top level globally.

UCAN capability format

[
  {
    "with": $RESOURCE,
    "can": $ABILITY,
    "nb": $EXTENSION
  },
  ...
]

In a UCAN capabilites are stored as an array of objects as defined above. These are stored in the att property of the UCAN.

• $RESOURSE - A string, needs to be a URI
• $ABILITY - A string verb representing allowed actions
• $EXTENSION - Any data, verifiers must know how to interpret or reject

ReCap capability format

{
   "def":[ $ABILITY, ... ],
   "tar":{
      $RESOURCE:[ $ABILITY, ... ],
      $RESOURCE:[ $ABILITY, ... ],
      $RESOURCE:[ $ABILITY, ... ]
   },
   "ext": $EXTENSION
}

• $RESOURSE - Any string
• $ABILITY - A string verb representing allowed actions
• $EXTENSION - Any data, verifiers do what they want with it

Open questions

• Does ReCap need global def?
• Why does ReCap need namespace

Suggestions

• Remove namespace from ReCap
• Remove ext from ReCap
• Add prf to ReCap for delegation in the same way UCAN does
• Force ReCap to use URIs for $RESOURSE
• Add nb field per $RESOURCE

This should make ReCap roughly equivalent to UCAN.