https://ieeexplore.ieee.org/document/8776589

1) Foundational Property

The properties (Figure 8) fundamental to the notion of self-sovereignty are placed under this group. These represent the core group of properties without which a self-sovereign identity cannot exist. The properties are depicted next.

• Existence. A self-sovereign identity must enable a user to encode her characteristics digitally to assert her existence in the digital domain. This essentially is a quasi-representation of one’s self in digital form.
• Autonomy. A self-sovereign identity must support full autonomy on the management and administration of identity information. A user must be fully independent on creating such an identity, as many as required, without relying on any party and be able to update/remove it when she wishes to do so.
• Ownership. A user must be the ultimate owner of a self-sovereign identity. This applies to any information encoding the identity, including the claims, whether it is self-asserted or provided by a third party.
• Access. A user must have unrestricted access to her identity information. She must be able to retrieve every single piece of information, including claims and assertions, which constitute her identity.
• **Single source.**A user should be the single source of truth regarding her identity. She should be the ultimate guardian to create self-asserted and/or accumulate third party asserted claims leveraging her identity and distribute them when required. This will ensure that third party cannot collude to exchange her identity data without her knowledge. For ease of use, however, she can delegate this task to an autonomous agent which is under her control.

FIGURE 8.

Taxonomy of the foundational property.

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2) Security Property

Under this group, we place those properties which are used to ensure the security of self-sovereign identity. The properties presented under this group are as crucial as the foundational properties to guarantee that the concept of security is tightly-coupled with any self-sovereign identity. The properties are presented in Figure 9 and discussed next.

• Protection. A self-sovereign identity should be well protected with latest cryptographic mechanisms satisfying the CIA (Confidentiality, Integrity and Authenticity) and non-repudiation properties. Each interaction involving an identity must be authorized and the corresponding entities must be properly authenticated. Any identity information must be stored in a secure manner and transmitted via a secure channel. Any system handling such identity must support a fine-grained access control mechanism to ensure the required level of controllability of the user over their identity.
• Availability. A self-sovereign identity must be readily available and accessible from different platforms when required by its owner. It must be robust enough to be recoverable even with the loss of a particular storage medium where such data is stored.
• Persistence. A self-sovereign identity must be persistent, at least as long as it is required by its owner. For third party claims, they must be persistent until the asserted authority ceases to exist.

FIGURE 9.