How It Works

Normalize Identifiers

Raw identifiers are normalized — phone numbers to E.164 format, emails to lowercase and trimmed. Both parties produce identical hashes from identical underlying identifiers.

SHA-256 Hash

Each normalized identifier is hashed with SHA-256 client-side. Output is the only data that will be exchanged — never the raw identifier. One-way function; cannot be reversed.

HKDF Key Derivation

A derived key is computed using HKDF-SHA256 over the Sender's master, the Recipient's public commitment, and a per-segment salt. Unique to this exchange. Neither party derives alone.

AES-256-GCM Wrap

Each SHA-256 hash is encrypted with AES-256-GCM using the derived key + unique nonce + segment metadata as AAD. Output is a wrapped token with no recoverable identifier information.

Ed25519 Sign

The Sender signs the bundle metadata with Ed25519. The signature proves origin and integrity. 64-byte deterministic signature. 10× faster than RSA-2048.

mTLS 1.3 Transmit

Signed, wrapped bundle is transmitted over mutual TLS 1.3. Both parties authenticate. No plaintext passes between environments at any point in the protocol.

Verify Signature

Recipient verifies Ed25519 signature against the Sender's registered public key. Bundle integrity confirmed. Any tampering is detectable — failed verification terminates the exchange.

AES-256-GCM Unwrap

Recipient locally derives the session key using their own master material and the Sender's public commitment + segment salt. Wrapped tokens unwrapped bilaterally. Hashes matched against partner cohort.