Title: Overview on IMS GLOSSARY

Glossary

1. Anonymity 

Anonymity is the state of being not identifiable within a set of subjects, the anonymity set. 

1. Authentication 

Authentication in the context of Identity Management is the process of validating the alleged identity of a person. Authentication requires that a user (intending to perform a specific action) provides a credential that proves he is in fact the person he claims to be. 

There are three main categories of credentials used to authenticate human users. Credentials are based on 

1. something the user is (identifiers based on biometrics); 

2. something the user has (hardware-based tokens such as smart cards/ software tokens such as digital certificates); 

3. something the user knows (password or PIN). 

Authentication methods can be combined in order to increase accuracy. It should be noted that while authentication is usually based on identification, authentication without identification is possible as well. 

1. Authorisation 

The process of determining, by evaluating applicable access control information, whether a user is allowed to have the specified types of access to a particular resource is called authorisation. This always requires authentication. Once a user is authenticated, he may be authorised to perform different types of access.

1. Credential 

In the widest sense, a credential is a piece of information attesting to the truth of certain stated facts. Credentials are used in the process of authentication, and in this context are based on the following technologies: Biometrics, digital certificates, smart cards, passwords etc. 

1. Identification 

Identification of a subject is the process of linking this subject to an identity. 

1. Identifier, ID 

An identifier (ID) is a name or string of bits. IDs can be assigned to subjects and objects. An identifier for a subject – with respect to a given community – is any information that uniquely characterises this subject in this community. 

1. Identity 

An identity is a set of characteristics representing a subject.  

1. Identity management 

Identity management means managing the various partial identities, i.e., their valuation as “applicable to one self” (role taking) or forming them (role making). A prerequisite to choose the appropriate partial identity is to recognise the situation the person is acting in. 

1. LDAP – Lightweight Directory Access Protocol 

LDAP is a directory access protocol standardised by the Internet Engineering Task Force (IETF) within the Requests for Comments (RFCs) 1777, 1778, 1779 and 1781. It describes the communication between directory clients and servers and the structure of the content of directories, not the content of them itself. 

1. Partial Identity 

Each identity of a subject can comprise many partial identities of which each represents the subject in a specific context or role. Partial identities are subsets of attributes of a complete identity. On a technical level, these attributes are data. 

1. Privacy 

Privacy is the ability of a person to control the availability of information about and exposure of himself or herself. It is related to being able to function in society anonymously (including pseudonymous or blind credential identification). 

1. Unlinkability 

Unlinkability of two or more items (e.g., subjects, messages, events, actions, …) means that within this system, these items are no more and no less related than they are related concerning the a-priori knowledge. 

1. XML – Extensible Markup Language 

XML standardised by the World Wide Web Consortium (W3C) is a simple, flexible text format derived from SGML (ISO 8879).