> For the complete documentation index, see [llms.txt](https://brightid.gitbook.io/aura/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://brightid.gitbook.io/aura/future-tools/known-identifiers.md).

# Known Identifiers

The Known Identifiers tool can be a simple and very powerful way to confirm that a person is only using one BrightID account.

It relies on an Aura Player knowing which identifiers (such as social accounts, legal names, addresses, phone numbers) are associated with a person. This knowledge comes from an existing relationship with that person, since [Aura Players should not ask subjects for personally identifying information](/aura/intro/how-aura-works.md#privacy).

Using a [Socialist Millionaire Protocol](https://en.wikipedia.org/wiki/Socialist_millionaire_problem#Off-the-Record_Messaging_protocol), Aura Players can agree on the same BrightID account without revealing any new private information to each other.

[See the post on known identifiers for a full description.](https://hackmd.io/@castall/BJblkURE5)