Digital identity

Digital identity refers to the aspect of digital technology that is concerned with the mediation of people's experience of their own identity and the identity of other people and things. Digital identity also has another common usage as the digital representation of a set of claims made by one digital subject about itself or another digital subject.

Digital subject

A digital subject is an entity represented or existing in the digital realm which is being described or dealt with. Every digital subject has a finite, but unlimited number of identity attributes. A digital subject can be human or non-human. Non-human examples include:

Devices and computers (which allow us to penetrate the "digital realm" in the first place);
Digital resources (which attract us to it);
Policies and relationships between other digital subjects (e.g., between humans and devices or documents or services).

Identity through relationship

An observer's perception of the digital identity of an entity is inevitably mediated by the subjective viewpoint of that observer (just as it is with physical identity). In order to attribute a digital representation to an entity, and so to elide the two as a digital subject, the attributing party (the observer) must trust that the representation does indeed pertain to the entity (see Authentication below). Conversely, the entity may only grant the observer selective access to its informational attributes (according to the identity of the observer from the perspective of the entity). In this way, digital identity is better understood as a particular viewpoint within a mutually-agreed relationship than as an objective property. This contextual nature of digital identity is referred to as contextual identity.

Authentication

Authentication is a key aspect of trust-based identity attribution, providing a codified assurance of the identity of one entity to another. Authentication methodologies include the presentation of a unique object such as a bank credit card, the provision of confidential information such as a password or the answer to a pre-arranged question, the confirmation of ownership of an e-mail address, and more robust but relatively costly solutions utilising encryption methodologies. In general, business-to-business authentication prioritises security while user to business authentication tends towards simplicity. New physical authentication techniques such as iris scanning, handprinting, and voiceprinting are currently being developed and in the hope of providing improved protection against identity theft.

Identifiers

Digital identity fundamentally requires digital identifiers—strings or tokens that are unique within a given scope (globally or locally within a specific domain, community, directory, application, etc.). Identifiers are the key used by the parties to an identification relationship to agree on the entity being represented. Identifiers may be classified as omnidirectional and unidirectional. [1] Omnidirectional identifiers are intended to be public and easily discoverable, while unidirectional identifiers are intended to be private and used only in the context of a specific identity relationship.

Identifiers may also be classified as resolvable or non-resolvable. Resolvable identifiers, such as a domain name or e-mail address, may be dereferenced into the entity they represent, or some current state data providing relevant attributes of that entity. Non-resolvable identifiers, such as a person's real-world name, or a subject or topic name, can be compared for equivalence but are not otherwise machine-understandable.

There are many different schemes and formats for digital identifiers. The most widely used is Uniform Resource Identifier (URI) and its internationalized version Internationalized Resource Identifier (IRI)—the standard for identifiers on the World Wide Web. OpenID and Light-Weight Identity (LID) are two web authentication protocols that use standard HTTP URIs (often called URLs), for example.

A new OASIS standard for abstract, structured identifiers, XRI (Extensible Resource Identifiers), adds new features to URIs and IRIs that are especially useful for digital identity systems. OpenID also supports XRIs, and XRIs are the basis for i-names.

Policy aspects of digital identity

There are proponents of treating self-determination and freedom of expression of digital identity as a new human right.^{[citation needed]} Some have speculated that digital identities could become a new form of legal entity.^{[citation needed]}

Taxonomies of identity

Digital identity attributes—or data—exist within the context of ontologies. A simple example of a taxonomy is "A cat is a kind of animal." An entity represented in this ontology as a "cat" is therefore invariably also considered an "animal." In establishing the contextual relationship of identity attributes to one another, taxonomies are able to represent identity in terms of pre-defined structures. This in turn allows computer applications to process identity attributes in a reliable and useful manner. XML (eXtensible Markup Language) has become a de facto standard for the abstract description of structured data.

Taxonomies inevitably reflect culturally and personally relative world views. Consider two possible elaborations of the above example:

"A cat is a kind of animal. A domestic cat is a kind of cat and is a pet."
"A cat is a kind of animal. A domestic cat is a kind of cat and is edible by humans."

Someone searching the first taxonomy for pets would find "domestic cat," whereas a search of the second taxonomy for foodstuffs would yield the same result! We can see that while each taxonomy is useful within a particular cultural context or set of contexts, neither represents a universally valid point of view on domestic cats.

The development of digital identity network solutions that can interoperate taxonomically-diverse representations of digital identity is a contemporary challenge. Free-tagging has emerged recently as an effective way of circumventing this challenge (to date, primarily with application to the identity of digital entities such as bookmarks and photos) by effectively flattening identity attributes into a single, unstructured layer. However, the organic integration of the benefits of both structured and fluid approaches to identity attribute management remains elusive.

Networked identity

Identity relationships within a digital network may include multiple identity entities. However, in a decentralised network like the Internet, such extended identity relationships effectively require both (a) the existence of independent trust relationships between each pair of entities in the relationship and (b) a means of reliably integrating the paired relationships into larger relational units. And if identity relationships are to reach beyond the context of a single, federated ontology of identity (see Taxonomies of identity above), identity attributes must somehow be matched across diverse ontologies. The development of network approaches that can embody such integrated "compound" trust relationships is currently a topic of much debate in the blogosphere.

Integrated compound trust relationships allow, for example, entity A to accept an assertion or claim about entity B by entity C. C thus vouches for an aspect of B's identity to A.

A key feature of "compound" trust relationships is the possibility of selective disclosure from one entity to another of locally relevant information. As an illustration of the potential application of selective disclosure, let us suppose a certain Diana wished to book a hire car without disclosing irrelevant personal information (utilising a notional digital identity network that supports compound trust relationships). As an adult, UK resident with a current driving license, Diana might have the UK's Driver and Vehicle Licensing Agency vouch for her driving qualification, age and nationality to a car-rental company without having her name or contact details disclosed. Similarly, Diana's bank might assert just her banking details to the rental company. Selective disclosure allows for appropriate privacy of information within a network of identity relationships.

A classic form of networked digital identity is the "White Pages". An electronic white pages links various devices, like computers and telephones, to an individual or organization. Various attributes are captured under a schema, and published in a LDAP or X.500 directory. Changes to the LDAP standard are managed by working groups in the IETF, and changes in X.500 are managed by the ITU.

External links

The Identity Dictionary
Digital Identity Glossary
FIDIS (Future of Identity in the Information Society) Network of Excellence
"Digital Identity" (book) by Phil Windley
Identity Gang Lexicon
Identity 2.0 Keynote
Ideating Identity