@keywords is, of, a.

@prefix log: <http://www.w3.org/2000/10/swap/log#> .
@prefix crypto: <http://www.w3.org/2000/10/swap/crypto#> .
@prefix str: <http://www.w3.org/2000/10/swap/string#> .

@prefix foaf: <http://xmlns.com/foaf/0.1/>.
@prefix session: <http://redfoot.net/2005/session#>.
@prefix rein: <http://dig.csail.mit.edu/2005/09/rein/network#> .
@prefix http: <http://dig.csail.mit.edu/2005/09/rein/examples/http-access#> .
@prefix t: <http://dig.csail.mit.edu/2005/09/rein/examples/troop#> .
@prefix : <http://dig.csail.mit.edu/2005/09/rein/examples/troop42#> .

@forAll REQ, PHOTO, LOC, WHO, PG, X, TXT.

# policy language used 
<> rein:policy-language <http://dig.csail.mit.edu/2005/09/rein/examples/http-access.rdf>. 

{ <http://dig.csail.mit.edu/2005/09/rein/examples/troop42.rdf> log:semantics ?F } => { ?F a TroopStuff }.


# Photos take at meetings of the troop can be shared with any  
# current member of the troop
# troop page lists current members and their foaf pages
# the requester is a member of the troop if the secret provided
# can be verified against the foaf:hexdigest of foaf pages of
# one of the members
{ REQ a rein:Request.
  REQ rein:resource PHOTO.
  ?F a TroopStuff; log:includes
        { PHOTO a t:Photo; t:location LOC.
          LOC a t:Meeting }.

  REQ rein:requester WHO.
  WHO session:secret ?S.
  ?S crypto:md5 TXT.

  ?F a TroopStuff; log:includes
        { [] t:member [ is foaf:maker of PG ].
          LOC t:attendee [ is foaf:maker of PG ] }.
  PG log:semantics [ log:includes
        { PG foaf:maker [ session:hexdigest TXT ] }
    ].

} => { WHO  http:can-get PHOTO }.


# Photos taken at a jamboree can be shared with anyone in the  
# troop or with anyone who attended the jamboree.

# (i) anyone who is in the troop
{ REQ a rein:Request.
  REQ rein:resource PHOTO.
  ?F a TroopStuff; log:includes 
	{ PHOTO a t:Photo; t:location LOC. 
	  LOC a t:Jamboree }.

  REQ rein:requester WHO.
  WHO session:secret ?S.
  ?S crypto:md5 TXT.

  ?F a TroopStuff; log:includes
    	{ [] t:member [ is foaf:maker of PG ]. }.
  PG log:semantics [ log:includes
        { PG foaf:maker [ session:hexdigest TXT ] }
    ].

} => { WHO  http:can-get PHOTO }.


# (ii) anyone who attended the jamboree
{ REQ a rein:Request.
  REQ rein:resource PHOTO.
  ?F a TroopStuff; log:includes 
	{ PHOTO a t:Photo; t:location LOC. 
	  LOC a t:Jamboree }.

  REQ rein:requester WHO.
  WHO session:secret ?S.
  ?S crypto:md5 TXT.

  ?F a TroopStuff; log:includes
    	{ LOC t:attendee [ is foaf:maker of PG ]. }.
  PG log:semantics [ log:includes
        { PG foaf:maker [ session:hexdigest TXT ] }
    ].

} => { WHO  http:can-get PHOTO }.



# policy rule states only members of the troop have access to pics on the policyaware site
# troop page lists members and their foaf pages
# foaf page includes hexstring of their password
# uses the properties of the rein:Request class
#{ [] rein:requester WHO.
#  WHO session:secret ?S.
#  ?S crypto:md5 TXT.
#  ?F a TroopStuff; log:includes
#    { thisTroop member [ is foaf:maker of PG ] }.
#  PG log:semantics [ log:includes 
#	{ PG foaf:maker [ session:hexdigest TXT ] } 
#    ].
#  [] rein:resource ?PHOTO.
#  ?PHOTO log:uri [ str:startsWith "http://demo.policyawareweb.org/images/group.jpg" ].
#} => { WHO  http:can-get ?PHOTO }.

# simple policy that lists the people who have access to the pics
# uses the properties of the rein:Request class
{ [] rein:requester WHO.
  WHO session:login :amy.
  [] rein:resource ?PHOTO.
  ?PHOTO log:uri [ str:startsWith "http://demo.policyawareweb.org/images/" ].
} => { WHO http:can-get ?PHOTO }.

# no-one with the secret "girlscout" has access to any picture
# uses the properties of the rein:Request class
#{ [] rein:requester WHO. 
#  WHO session:secret "girlscout".
#  [] rein:resource ?PHOTO.
#  ?PHOTO log:uri [ str:startsWith "http://www.policyawareweb.org/" ].
#} => { WHO  http:cannot-get ?PHOTO }.

# possible to write policies without using rein:Request properties
{ WHO t:member t:w3c.
  ?PHOTO a http:photo.
  ?PHOTO log:uri [ str:startsWith "http://demo.policyawareweb.org/images/group.jpg" ].
} => { WHO http:can-get ?PHOTO }.

#ends