In moving towards ubiquitous online services and hybrid network environment, a highly complex identity management environment is emerging due to the diversity of protocols, networks and devices as well as user requirements. The combination of distributed attributes and identities are often not associated across identity management systems and carries different amount of security data. This causes difficulties due to multiple identities and raises the need for an efficient design of an identity management system. The multiplicities of approaches to and techniques for identity management, while dealing with the present challenges, have introduced new problems, especially the concern about privacy. Biometrics technologies nowadays are typically considered a vital component of the security requirements and are strongly attached to the basis of highly secure identification and authentication solutions. This paper describes the fundamental concepts of identity authentication and identity management systems. In this work we also propose and implement a multimodal Digital Identity Management System (IDMS) integrating pseudo metrics, physical metrics and biometrics techniques based on artificial neural networks.