Welcome to Anubis

Anubis Anubis is a flexible Policy Enforcement solution that makes easier to reuse security policies across different services, assuming the policies entail the same resource. In short we are dealing with policy portability :) What do you mean by that?

Let's think of a user that register some data in platform A. To control who can access his data he develops a set of policies. If he moves the data to platform B, most probably he will have to define again the control access policies for that data also in platform B.

Anubis aims to avoid that :) or at least simplify this as much as possible for the data owner. How? Leveraging open source solutions (e.g. Envoy, OPA) and reference standards (e.g. W3C WAC, W3C ODRL, OAUTH2).

Of course, the support for distributed policies management may be of value also for a single platform deployed distributedly, e.g. to synch policies across the cloud-edge.

Why this project?

Data portability often focuses on the mechanisms to exchange data and the formalisation of data representation: the emphasis is rarely put on the portability of security & privacy data policies. Enabling security and privacy data policy portability is clearly a step forward in enabling data sovereignty across different services.

This project aims at enabling data sovereignty by introducing data privacy and security policy portability and prototyping distributed data privacy and security policy management, thus contributing to increase trust toward data sharing APIs and platforms.

Approaches as the one proposed, increasing control by owners over their data and portability of data assets, are key to boost the establishment of trusted data spaces.

The project is looking into

  • Open standardized security & privacy data policies vocabulary.
  • Linking an existing user profiling vocabulary to the security & privacy data policies vocabulary as a way to increase portability of policies and their compatibility to existing standards.
  • A middleware supporting decentralised control and audit of security & privacy data policies by data owners (in the context of RESTful APIs).
  • Translation from the security & privacy data policies vocabulary to other policy languages or APIs that are actually used for PEP.

While Anubis is not subject to GDPR per se, it allows API owners to implement effective GDPR in their solutions.

Why did you pick Anubis as name?

Anubis is an ancient Egyptian god, that has multiple roles in the mythology of ancient Egypt. In particular, we opted for this name, because he decides the fate of souls: based on their weights he allows the souls to ascend to a heavenly existence, or condemn them to be devoured by Ammit. Indeed, Anubis was a Policy Enforcement system for souls :)

State of the art and standards

In the design and development of Anubis we tried to leverage different state-of-the-art solutions and standards:

  • W3C WAC, one of the reference vocabularies for expressing access control policies over web resources.
  • W3C ODRL, a policy expression language that allows representing statements about the usage of content and services.
  • OAUTH2 and OIDC the today reference protocols for authentication.
  • OPA the state of the art solution for cloud native policy evaluation (not necessarily applied to access control).

To an extent, Anubis' approach is comparable to MyData Framework by Fraunhofer IESE. The main differences are:

  • Anubis focuses on policy portability, and because of that, the starting point to express policies are existing vocabularies targeting interoperability, not a new policy language.
  • Anubis does not support data manipulation to reduce attributes or data elements that should not be accessed (not yet at least).
  • Anubis is meant to work distributedly, while MyData takes more a centralised approach.
  • Anubis tries to apply the principle that policies follows the data, while interoperability of policies and their portability are out of the scope of MyData.

There are also quite some similarities with FIWARE TRUE by Engineering. Interestingly enough, TRUE uses ODRL for providing usage control on top of My Data Framework in the context of IDSA. This has quite a number of complex architectural and requirements implications, that we believe are not suitable in scenarios where the source of trust and control is the owner of the data, and not a central authority. Other differences resemble the ones analyzed for My Data.


Policy Enforcement

In term of policy enforcement, Anubis adopts a standard architecture: a client request for a resource to an API, and based on the defined policies, the client is able or not to access the resource. The figure below shows the current architecture.

                            ┌──────────────┐        ┌──────────────┐
                            │   Policy     │   3    │    Policy    │
                            │   Decision   ├───────►│Administration│
                            │   Point      │        │    Point     │
                            └──────────────┘        └──────────────┘
                                 2 │
    ┌──────────────┐        ┌──────┴──────┐        ┌───────────────┐
    │              │   1    │   Policy    │   4    │   Protected   │
    │    Client    ├───────►│ Enforcement ├───────►│               │
    │              │        │    Point    │        │      API      │
    └──────────────┘        └─────────────┘        └───────────────┘
  1. A client requests for a resource via the Policy Enforcement Point (PEP) - implemented using an Envoy's proxy authz filter.
  2. The PEP pass over the request to the PDP (Policy Decision Point), provided by OPA which evaluates a set of rules that apply the abstract policies to the specific API to be protected;
  3. In combination with the policies stored in the PAP (Policy Administration Point), provided by the Policy Management API;
  4. If the evaluation of the policies returns allowed, then the request is forwarded to the Protected API.

Policy Management

Anubis currently supports only Role Based Access Control policies. Policies are stored in the Policy Management API, that supports the translation to WAC and to a data input format supported by OPA, the engine that performs the policy evaluation.

Policy Evaluation

The policy evaluation is performed by OPA, combining the data stored in the Policy Management API, and a set of API specific rule defined in Rego (OPA's native query language).

The role of Rego's rules is to apply policies that are API independent - policies identify their objects using Uniform Resource Name to define a unique identifier for data (as envisioned by NGSI-LD) - to the specific format of an API.

For example, we may have a policy that states anyone authenticated can read urn:mycool:resource:

    @prefix acl: <http://www.w3.org/ns/auth/acl#> .
    example:a0be6113-2339-40d7-9e85-56f93372f279 a acl:Authorization ;
        acl:accessTo urn:mycool:resource ;
        acl:accessToClass urn:mycool ;
        acl:agentClass acl:AuthenticatedAgent ;
        acl:mode acl:Read .

Rego's rules translate this policy to a GET request that contains a valid JWT token the api endpoint: http://myapi/resources/urn:mycool:resource

A different Rego rule can be defined to work on another API using a different authentication mechanism.

Policy Distribution

The policy distribution architecture relies on libp2p middleware to distribute policies across differed Policies Administration Points. The architecture decouples the PAP from the distribution middleware. This allows:

  • different PAP to share the same distribution node.
  • deployment without the distribution functionalities (and hence with a smaller footprint), when this is not required.

The distribution middleware is called Policy Distribution Point.

    ┌──────────────┐        ┌──────────────┐
    │   Policy     │        │    Policy    │
    │ Distribution │◄──────►│Administration│
    │   Point 1    │        │    Point 1   │
    └──────────────┘        └──────────────┘
         2 │
    ┌──────────────┐        ┌──────────────┐
    │   Policy     │        │    Policy    │
    │ Distribution │◄──────►│Administration│
    │   Point 2    │        │    Point 2   │
    └──────────────┘        └──────────────┘

There are two distribution modalities:

  • public, i.e. when the different middleware belong to different organisations in the public internet. In this case:

    • resources are considered to be univocally identifiable (if they have the same id they are the same resource);

    • only user specific policies are distributed;

    • only resource specific policies are distributed.

  • private, i.e. when the different middleware belong to the same organisation. In this case:

    • resources are considered to be univocally identifiable only within the same service and service path;

    • all policies are distributed (including the ones for roles and groups and * and default resource policies).

In the public modality, subscribers are required to define the service for which they subscribe on a certain resource. This guarantees that policies are stored in the correct service. e.g.:

curl --location --request POST 'http://localhost:8098/resource/urn:AirQuality:1/subscribe' \
--header 'fiware-Service: Tenant1' \
--header 'fiware-Servicepath: /'

Resource discovery takes an important role in the distribution process, to this aim a specific endpoint is available in the management api. A resource is considered managed by Anubis if there is at least an acl:Control policy associated to it. The actors of policies with mode acl:Control are considered as the owners of the resource.

The policy distribution is based on discovery and publish/subscribe mechanisms. Key interactions are described in the following sections.

Create a policy for an existing resource

Create a policy for an existing resource

In this interaction, when a new policy is created in the PAP 1:

  1. The notification is sent to the Policy Distribution Point 1.
  2. If a topic for the resource does not exist:
    1. The Policy Distribution Point 1 creates a topic for the resource to which the policy is related
    2. The Policy Distribution Point 1 registers as a content provider for the given resource.
  3. At this point, (if not yet registered to the topic), the Policy Distribution Point 1 register itself to the topic.
  4. The Policy Distribution 1 create a message on the topic.
  5. Other Policy Distribution Points subscribed to the topic are notified.
  6. Consequently, the notified Policy Distribution Points update related PAPs.

Create a new resource in a PEP

Create a new resource

In this interaction, when a new resource is created in the PAP 1:

  1. The notification is sent to the Policy Distribution Point 1.
  2. In case the topic for the resource is not existing in the distribution network:
    1. the Policy Distribution Point 1 creates a topic for the resource,
    2. The Policy Distribution Point 1 registers as a content provider for the resource.
    3. The Policy Distribution Point 1 registers to the topic.
  3. In case the topic for the resource already exist in the distribution network:
    1. The Policy Distribution Point 1 search content providers for the topic
    2. The Policy Distribution Point 1 ask for policies for the topic from other Policy Distribution Points
    3. The Policy Distribution Point 2 retrieves the policies from PAP 2
    4. The Policy Distribution Point 2 forward policies to the Policy Distribution Point 1
    5. The Policy Distribution Point 1 stores policies in PAP 1.


The User Manual and the Admin Guide cover more advanced topics.