Macaroon Caveats
================
`Macaroons`_ are issued by Matrix servers as authorization tokens. Macaroons may be restricted by adding caveats to them.
.. _Macaroons: http://theory.stanford.edu/~ataly/Papers/macaroons.pdf
Caveats can only be used for reducing the scope of a token, never for increasing it. Servers are required to reject any macroon with a caveat that they do not understand.
Some caveats are specified in this specification, and must be understood by all servers. The use of non-standard caveats is allowed.
All caveats must take the form::
key operator value
where:
- `` key `` is a non-empty string drawn from the character set [A-Za-z0-9_]
- `` operator `` is a non-empty string which does not contain whitespace
- `` value `` is a non-empty string
And these are joined by single space characters.
Specified caveats:
+-------------+--------------------------------------------------+------------------------------------------------------------------------------------------------+
| Caveat name | Description | Legal Values |
+=============+==================================================+================================================================================================+
| gen | Generation of the macaroon caveat spec. | 1 |
+-------------+--------------------------------------------------+------------------------------------------------------------------------------------------------+
| user_id | ID of the user for which this macaroon is valid. | Pure equality check. Operator must be =. |
+-------------+--------------------------------------------------+------------------------------------------------------------------------------------------------+
| type | The purpose of this macaroon. | - `` access `` : used to authorize any action except token refresh |
| | | - `` refresh `` : only used to authorize a token refresh |
| | | - `` login `` : issued as a very short-lived token by third party login flows; proves that |
| | | authentication has happened but doesn't grant any privileges other than being able to be |
| | | exchanged for other tokens. |
+-------------+--------------------------------------------------+------------------------------------------------------------------------------------------------+
| time | Time before/after which this macaroon is valid. | A POSIX timestamp in milliseconds (in UTC). |
| | | Operator < means the macaroon is valid before the timestamp, as interpreted by the server. |
| | | Operator > means the macaroon is valid after the timestamp, as interpreted by the server. |
| | | Operator == means the macaroon is valid at exactly the timestamp, as interpreted by the server.|
| | | Note that exact equality of time is largely meaningless. |
+-------------+--------------------------------------------------+------------------------------------------------------------------------------------------------+
