Dual Resolution

Summary

Parties engaged in a mutual interaction acquire each other’s decentralised identifier documents (DDOs) to access information necessary for verification (e.g., public key) and communication (e.g., service endpoints for provided services).

Context

Parties engaged in mutual or 2-ways interactions such as a buyer-seller or doctor-patient relationship. Each party has a self-sovereign identity.

Problem

When 2 or more parties want to establish interactions (e.g., for business purposes), each party first needs to determine the target party’s identity and means of communicating to proceed further. How can mutually interacting parties find and validate each other’s information?

Forces:

  • Authenticity – Decentralised identity is a self-sovereign technique for proving one’s identity.
  • Interoperability – For 2 parties to interact, the ways of communication have to be interoperable.
  • Independence – The interacting parties should remain independent of each other and one should not be able to pry on the other.

Solution

Each party could request and validate the other party’s identity and service information before initiating the 2-way interaction. First, record each party’s identity, communication, and ownership information as a decentralised identifier document (DDO) on an identifier registry smart contract. In this context, a DDO can contain verification methods (i.e., public keys) and service endpoints (e.g., messaging service details) of a party. Second, before initiating any formal interactions between the 2 parties, each should request for the other party’s DDO from the identity registry. Finally, if the retrieved DDO is valid, each party could establish the interaction with the other party using the communication information stored in DDOs. Such a process is referred to as dual resolution (aka., mutual resolution) and forms the first step of any multi-party interaction.

Dual resolution pattern

Dual resolution pattern

Benefits

  • Authenticity – A DDO carries decentralised identity information of a party that can be verified by another party. As both parties verify each other’s identity, mutual authentication is established based on self-sovereign identity.
  • Interoperability – The dual resolution process allows the interacting entities to obtain and validate each other’s identity and communication information.
  • Independence – Each DDO stores necessary communication information of the corresponding decentralised identity. Hence, a party’s different identities are independent of each other and cannot be correlated.

Drawbacks

  • Privacy – A party may store personally identifiable information in his/her DDO beyond what is necessary for communication, e.g., social media accounts and personal websites. While doing so increases the trustworthiness of the party, it also increases the risk of unwillingly revealing the entity’s personal information.

Related patterns

Known uses

  • The existing self-sovereign identity applications do not directly point out this feature as a provided functionality. But the users need to resolve each other’s DID when there is potential interaction.