Protocol Glossary
New to privacy-preserving infrastructure? Explore the technical terms and technologies that power the Herald notification layer.
ZK Notifications
Notifications that include a zero-knowledge proof (ZK-proof) of delivery. This allows a sender to prove a message was delivered to the correct recipient without revealing the recipient's identity or contact details.
Privacy Registry
A specialized Anchor program on the Solana blockchain that stores encrypted contact information (blobs) in Program Derived Addresses (PDAs). Only the owner's wallet and Herald's secure enclave can interact with these records.
Nitro Enclave
An isolated compute environment (AWS Nitro) where sensitive data is decrypted in-memory. The enclave has no persistent storage and no external network access, ensuring that decrypted email addresses or phone numbers never leave the secure boundary.
PDA (Program Derived Address)
A unique account address on Solana that is derived from a program ID and a set of seeds. Herald uses PDAs to store encrypted user identities, indexed by the user's public key.
Zero-PII
An architectural standard where a system never collects, stores, or processes Personally Identifiable Information in a readable form. Herald is a Zero-PII infrastructure provider.
Attestation
A cryptographic proof that a specific piece of software is running inside a secure enclave without modification. This allows users to verify that Herald's code is behaving as documented.
Deepen your understanding
Want to see the math and architecture diagrams behind these terms? Head over to our technical documentation for a full deep dive.