Biblio

Identity management is an essential cornerstone of securing online services. Service provisioning relies on correct and valid attributes of a digital identity. Therefore, the identity provider is a trusted third party with a specific trust requirement towards a verified attribute supply. This trust demand implies a significant dependency on users and service providers. We propose a novel attribute aggregation method to reduce the reliance on one identity provider. Trust in an attribute is modelled as a combined assurance of several identity providers based on probability distributions. We formally describe the proposed aggregation model. The resulting trust model is implemented in a gateway that is used for authentication with self-sovereign identity solutions. Thereby, we devise a service provider specific web of trust that constitutes an intermediate approach bridging a global hierarchical model and a locally decentralized peer to peer scheme.

In recent years, Attribute Based Access Control (ABAC) has evolved as the preferred logical access control methodology in the Department of Defense and Intelligence Community, as well as many other agencies across the federal government. Gartner recently predicted that “by 2020, 70% of enterprises will use attribute-based access control (ABAC) as the dominant mechanism to protect critical assets, up from less that 5% today.” A definition and introduction to ABAC can be found in NIST Special Publication 800-162, Guide to Attribute Based Access Control (ABAC) Definition and Considerations and Intelligence Community Policy Guidance (ICPG) 500.2, Attribute-Based Authorization and Access Management. Within ABAC, attributes are used to make critical access control decisions, yet standards for attribute assurance have just started to be researched and documented. This presentation outlines factors influencing attributes that an authoritative body must address when standardizing attribute assurance and proposes some notional implementation suggestions for consideration. Attribute Assurance brings a level of confidence to attributes that is similar to levels of assurance for authentication (e.g., guidelines specified in NIST SP 800-63 and OMB M-04-04). There are three principal areas of interest when considering factors related to Attribute Assurance. Accuracy establishes the policy and technical underpinnings for semantically and syntactically correct descriptions of Subjects, Objects, or Environmental conditions. Interoperability considers different standards and protocols used for secure sharing of attributes between systems in order to avoid compromising the integrity and confidentiality of the attributes or exposing vulnerabilities in provider or relying systems or entities. Availability ensures that the update and retrieval of attributes satisfy the application to which the ABAC system is applied. In addition, the security and backup capability of attribute repositories need to be considered. Similar to a Level of Assurance (LOA), a Level of Attribute Assurance (LOAA) assures a relying party that the attribute value received from an Attribute Provider (AP) is accurately associated with the subject, resource, or environmental condition to which it applies. An Attribute Provider (AP) is any person or system that provides subject, object (or resource), or environmental attributes to relying parties regardless of transmission method. The AP may be the original, authoritative source (e.g., an Applicant). The AP may also receive information from an authoritative source for repacking or store-and-forward (e.g., an employee database) to relying parties or they may derive the attributes from formulas (e.g., a credit score). Regardless of the source of the AP's attributes, the same standards should apply to determining the LOAA. As ABAC is implemented throughout government, attribute assurance will be a critical, limiting factor in its acceptance. With this presentation, we hope to encourage dialog between attribute relying parties, attribute providers, and federal agencies that will be defining standards for ABAC in the immediate future.