Wirtschaftsuniversität Wien Magisterarbeit - SemanticLab

3.2.1. EPAL - an introduction
EPAL was developed by IBM and is, similar to P3P, based on XML-files. The two
main goals of EPAL are to “provide the ability to encode an enterprise’s privacy-related
data-handling policies and practices” and to be a “language that can be imported and
enforced by a privacy-enforcement systems” [IBM03]. As these two statements suggest,
EPAL has a different goal than P3P. Whereas P3P wants to make published privacy
policies on enterprises’ websites machine-readable with predefined vocabularies, “EPAL
aims at formalizing enterprise-internal privacy policies” [IBM03]. This requires a
very detailed set of vocabulary specifically tailored to the needs of enterprises. Unlike
P3P, EPAL has the specific goal not to be a language with a universal vocabulary.
As long as all involved parties agree on and understand the vocabularies being used,
organizations can define a set of vocabularies which fits their needs. In addition to that,
EPAL policies can be enforced as they are parsed by an enforcement engine. That means
that EPAL was ‘developed mainly as a business-to-business (B2B) technology to help
streamline information flows during business interactions” and that “it helps [to] ensure
that information is protected and used in accordance with the responsible organizations
privacy policies” [Stu04]. However, EPAL has, similar to P3P, some requirements which
are going to be dealt with in the next section.
3.2.2. Requirements
The EPAL specification defines requirements which are not designed for any specific
platform or software. It rather aims at defining requirements how EPAL policies and
their meaning actually have to be formed and expressed: One requirement is that a
rule may be “allowed” or “denied” or have no defaulting ruling at all or that each rule
must contain a set of conditions that must be true to make the rule active. It is also a
requirement that a rule may contain obligations which have to be executed if an action
has to be performed (e.g. that accessing a certain file must be documented in a specific
way).
3.2.3. EPAL policies
Unlike P3P, EPAL does not have any predefined elements. “EPAL provides a mechanism
for defining the elements which are used to build the policy” [IBM03]. To build an
EPAL policy, a set of rules has to be compiled whereas these rules have to be ordered
with descending precedence. Similar to P3P, EPAL has elements which define a rule
statement: a ruling, a user category, an action, a data category, and a purpose - and it
optionally can contain conditions and obligations. The following example shows how to
convert a privacy policy into an EPAL privacy rule. The informal privacy policy
Allow a sales agent or a sales supervisor to collect a customer’s data for
order entry if the customer is older than 13 years of age and the customer
has been notified of the privacy policy. Delete the data 3 years from now.
(Source: [IBM03])
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