Several studies highlight how evolving identity management models over the past decade have had significantly different impacts on citizen privacy, service interoperability, adoption by public and private sectors, and states' digital sovereignty ambitions.

This section examines four major digital identity models identified in the literature — centralised, federated and user-centric, and self-sovereign identity (SSI) — outlining their key features, real-world applications, tensions, and how they are linked to achieving digital sovereignty.

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Several studies highlight the growing significance of national digital identity as crucial but contested systems — both as a response to the digital acceleration caused by COVID-19 and the emergence of governments' digital sovereignty ambitions (Naghmouchi et al., 2023; Anand & Brass, 2021; Fernández, 2022; Sedlmeir et al., 2022). These studies draw a clear link between the urgency to "solve digital identity" (Stokkink & Pouwelse, 2018) and the considerable evolution of digital identity management models over the past decade — from centralised and federated systems, which spread risk but leave individuals dependent on institutional gatekeepers, to the emergence of user-centred and self-sovereign identity (SSI) models that look to place individuals at the centre of identity management to protect their privacy and security (Rim, 2023; Weigl, Barbereau & Fridgen, 2023; Zwitter et al., 2020; Wang & De Filippi, 2020).

Contemporary national digital identity systems now vary widely, facing a range of technical design choices which have significant implications for citizen privacy, service interoperability, adoption by public and private sectors, and a state's digital sovereignty objectives. The following sections examine the major digital identity management models identified within the literature—federated, user-centered, and SSI—in more detail, outlining their key features, advantages, and challenges in the context of achieving digital sovereignty.