principal

For all these reasons, the foundational precept of DPKI is that identities belong to the entities they represent. That requires designing a decentralized infrastructure where every identity is controlled not by a trusted third-party, but by its principal owner.

Online communications are secured through the safe delivery of public keys. These keys correspond to identities. The entity these identities represent, called the principal, uses a corresponding secret private key to both decrypt messages sent to them, and to prove they sent a message (by signing it with the private key).

https://github.com/WebOfTrustInfo/rebooting-the-web-of-trust/blob/master/draft-documents/Decentralized-Public-Key-Infrastructure-CURRENT.md#the-security-of-online-communication