REFEREE Sample Policy 5

Check document hash and defer trust to GoodMouseClicking

Scenario: T The policy used in this section extends sample policy 4 of the previous section to include checking of hash functions. Here we emphasize the way different modules interact with each other as well as the data flow.
Policy in English: Get the PICS labels about the document as well as GoodMouseClicking's endorsement about the label raters from the label bureau "http://label.com". Allow viewing this URL only if the endorsement is found, hash is verified, and the violin rating is less than 2.
Output: TRUE because all conditions stated above match. The PICS label with the hash verification and GoodMouseClicking endorsement is returned.
Explanation: "check-hash" module right now is only a stub; it vouches for any PICS label containing 'md5' field. The final pattern matcher says that the PICS labels are valid only if both "endorse-label" and "check-hash" place the stamp on it. You can imagine adding digital signature to verify authenticity in a similar fashion.
DIY: Do-It-Yourself: You can delete the 'md5' field of the PICS label to get a 'FALSE' output.

Action: URL:

Corresponding Profiles-0.92 policy for the action:
(invoke "load-label" STATEMENT-LIST URL "http://www.musac.org/v1.0" ("http://labels.com/")) (invoke "check-hash" STATEMENT-LIST) (invoke "endorse-label" STATEMENT-LIST "mailto:GoodMouseClicking@w3.org" ("http://labels.com/")) (false-if-unknown (match (("endorse-label" "check-hash" *) (* "mailto:GoodMouseClicking@w3.org" * ((version "PICS-1.1") * (service "http://www.musac.org/v1.0") * (ratings * (RESTRICT < v 2) * )))) STATEMENT-LIST))

PICS labels being fetched:
(PICS-1.1 "http://www.musac.org/v1.0" labels by "alice@rater.org" md5 "7A2B1a2bA72BxyzyplehJQ==" ratings (v 1))

Raters in which GoodMoouseClicking vouches for:

Yang-Hua Chu

Last modified: Fri Apr 4 23:58:51 EST