Listing 2: ODRL Purpose Constraint.
1 ” c o n s t r a i n t ” : [ {
2 ” l e f t O p e r a n d ” : ” p u r p o s e ” ,
3 ” o p e r a t o r ” : ” eq ” ,
4 ” r i g h t O p e r a n d ” : { ” @value ” : ” M a r k e t i n g
” , ” @type ” : ” x sd : s t r i n g ” }
5 } ]
Overall, in order to transform an ODRL policy
into a policy that is specified in any other ILP than
MYDATA, we can follow the same mapping rules and
update the algorithm, correspondingly.
5 POLICY NEGOTIATION
A negotiation is a process that occurs between at least
two parties about a certain subject and is driven by
their demands (Bennicke et al., 2003). In a policy ne-
gotiation process in the IDS, the subject is the Data
Usage Control policy, and the demands reflect the
involved parties’ security and privacy requirements.
Thus, an agreed policy is the outcome of the process.
Data consumers may have different data us-
age preferences and system architectures than data
providers and use different policy enforcement tech-
nologies. Therefore, they may request changes on
the consumer-side policies that are published by the
data providers on the IDS platform. In the context
of the IDS, an offer policy addresses the usage policy
of a specific data asset. A data consumer evaluates
whether it is possible to technically enforce the offer
policy at the data consumer side and whether the pol-
icy complies with his demands. For example, when
the data consumer requires to use the data in a spe-
cific time interval, the policy needs to be evaluated to
check whether it is offering the usage of data within
that desired time slot. After the evaluation, either the
data consumer entirely agrees to the conditions spec-
ified in the offered policy, or it requires to slightly
change the policy. Consequently, the data consumer
creates a suitable request policy, attaches it to a re-
quest message and sends it to the data provider. The
policy negotiation process is initiated as soon as the
data consumer sends the request message to the data
provider as shown in the Figure 4. The data provider
evaluates the received request policy and creates a
corresponding new offer policy and send it back to the
data consumer. The parties may build their own pol-
icy evaluation components that automatically evalu-
ate the received policies and generate the correspond-
ing new offer or request policies. The policy nego-
tiation process continues until the data provider and
data consumer agree on a Data Usage Control policy
that addresses their needs and can be enforced within
their systems. When the request policy matches the
offer policy, the data provider creates an agreement
policy, and sends it to the data consumer as an agree-
ment message. Next, the data consumer has to ac-
knowledge the agreement policy. The data provider
can always send a reject message as a reply to a re-
quest message and thus require to terminate the policy
negotiation process.
It might be a drawback of an automated policy ne-
gotiation process that the data consumer can create
new request policies aiming to achieve an agreement
with the least restrictions. However, the policy nego-
tiation process is not necessarily about achieving an
agreement that minimizes the security restrictions of-
fered by the data provider, but it is about achieving
an agreement that fits best to both parties’ demands
and the technical feasibility of the enforcement tech-
nologies. In fact, the demands may have inverse cor-
relations. For example, a data provider may accept
that the data consumer uses the data in a different sys-
tem and for different purposes than originally offered,
but may in return insist on a shorter usage period.
However, the details of the policy negotiation process,
such as where the policy evaluation component is lo-
cated or the mode of operation of the time-out han-
dling mechanism, is not the focus of this paper, but
rather the policy negotiation approaches and their pa-
rameters.
5.1 Policy Negotiation Approaches
In an ideal case, the negotiation process lasts only
for one round since the data consumer accepts an of-
fer policy as it is published and the data provider is-
sues the agreement policy accordingly. At most, a
data provider provides the possibility to choose N out
of M optional ODRL policy rules and the data con-
sumer then selects those rules that match his demands.
We call this approach a fully automated approach in
which no further modification of the offered policies
is accepted. On the other hand, in order to automate a
human-like interactive approach with no restrictions,
the parties need to build the policy evaluation com-
ponents that interpret and define the policies like hu-
mans. This is a very complex task. Therefore, we pro-
pose to build a policy evaluation component that ben-
efits from the extracted policy classes and evaluates
the received policies, accordingly. Also, it generates a
corresponding new policy with or without user inputs.
As listed in Table 1, the interactive approach with lim-
ited modifications provides a platform that uses such a
proposed policy evaluation component and allows the
parties to negotiate over predefined, known negotia-
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