Offline verification of SSI

Abstract

When the internet was first created no one thought about an identity layer because during the initial days, the main objective of the internet was to interchange data among people. No one was concerned about who was sharing the data with them. But as the number of users increased rapidly, suddenly the need for identity was recognised as it became apparent that anyone could impersonate someone else over the internet. To mitigate this issue, providers designed different identity models and adopted those models to provide identities to their users so that they could be independently identified. However, these models have numerous issues. For example the models do not solve how the validation will happen if both parties are offline, one model uses time-stamp but it does not solve the problem of real-time offline validation. Unfortunately, managing the identities provided by the providers was hard and users have limited control over their identity data. To mitigate these issues, the concept of Self-sovereign Identity (SSI) has been introduced. Through this approach users maintain their digital identity in a decentralised manner and have full control over it. Self sovereign identity has three parties. The user, the issuer and the verifier. The issuer issues a verifiable credential for the user and the verifier can verify it with the verifiable presentation that the user provides. To facilitate this interaction SSI utilises blockchain to store important metadata, SSI documents and public keys and it is important that the verifier and the blockchain is online during the verification process. The problem arises when the verifier and holder does not have access to the internet. In this research we will explore how SSI verification can be facilitated even when the verifier and holder is offline.