Overview
Data capture requires the provision of immutable fields in order to capture and store collected data. Immutable capture items are identified by passive identifiers.
Table: A hash grid table describing the different states of active and passive identifiers. The two states of passive identifiers are highlighted.
What is a Passive identifier?
An immutable identifier used to identify a non-governing entity, an inanimate object, or a static data item. A passive identifier can either be (1) controlled by an active identifier or (2) not controlled.
- Controlled passive identifier (p/a-linkage)
In general, passive identifiers for non-human resources do not need to be controlled. However, as soon as you have any need to express ownership, control, or management of that resource, you need to relate it to an active identifier. An active identifier identifies an entity that has the capacity to govern.
The figure shows an instance when the DID subject may not be the same as the DID controller. In this scenario, the subject may represent a passive non-governing entity, an inanimate object or a static data item with the controller’s DIDs being active, requiring a signing key for identity authentication. Through the authentication process, the controller is able to express ownership, control, or management of the passive resource.
- Uncontrolled passive identifier
An immutable identifier that does not require any form of ownership, control, or management.
Common types of passive identifier
Passive identifier types include:
Resource identifier
An identifier that contains a cryptographic hash of digital content. Any change to the binary state of a single byte of the digital content will invalidate the hash. A hash value is an immutable fingerprint for digital content.
Linking identifier (p/p-linkage)
An identifier that has an association with a cryptographic hash of digital content that can be used for linking information across a number of objects, applications, and/or systems. A linking identifier can be referenced in multiple locations and, as such, changing any single reference of the linking identifier should propagate throughout the daisy chain. As a linking identifier tends to be governed, this threading property works well for data revocation where a governing entity has the capability of revoking all data associated with the linking identifier.
Technical requirements
Passive identifiers are assigned to the Semantic domain. Technical requirements include:
- Cryptographic hashes. A cryptographic hash is a checksum or digital fingerprint derived by performing a one-way hash function (a mathematical operation) on the data comprising a computer program (or other digital files). Any change in just one byte of the data comprising the computer program will change the hash value. A hash value is, therefore, a unique fingerprint for any program or other digital files.