THIIC Tokenized Healthcare Identity Interchange Cryptography
SESSION ACTIVE · ----
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PROTOCOL · v1.0 · 2026

Bilateral identity exchange.
No PII in transit.
No vendor middleware.

THIIC is a cryptographic protocol that lets two parties exchange hashed healthcare identifiers without either side transmitting raw PII — or trusting a third-party intermediary.

ARCHITECTURE · 5 OPERATIONS BILATERAL
01 Key Agreement — Ed25519 keypairs generated independently. Public keys exchanged only.
02 Session Key Derivation — HKDF-SHA256 derives a scoped symmetric key from shared secret + nonce.
03 Hash & Wrap — SHA-256 hashes identifiers with session-derived salt. AES-256-GCM encrypts payload.
04 Signed Transmission — Ciphertext is Ed25519-signed. Recipient verifies provenance before decrypt.
05 Bilateral Match — Recipient hashes locally. Match by hash comparison. Neither party's raw IDs leave their environment.

THIIC is a protocol, not a platform. It composes four standard cryptographic primitives — SHA-256, HKDF-SHA256, AES-256-GCM, and Ed25519 — in a bilateral salting configuration that lets two parties exchange hashed patient identifiers without either party possessing enough cryptographic context to act alone.

The protocol was designed for healthcare data partnerships: bilateral exchanges between a data licensor and an activation partner, where HIPAA compliance, audit defensibility, and removal of vendor middleware are first-class architectural requirements.

THIIC is not new cryptography. It is a specific, documented configuration of proven NIST- and IETF-standardized primitives, optimized for the exact shape of a pharma audience data exchange. Every primitive has published test vectors, independent review, and decades of real-world deployment.

CRYPTOGRAPHIC PRIMITIVES
SHA-256
FIPS 180-4 · Identifier Hashing
Applied to each raw identifier (phone, email, NPI) with a session-derived salt. The original PII never enters the transport layer — only the deterministic hash does.
HKDF-SHA256
RFC 5869 · Session Key Derivation
Derives a symmetric session key from the shared secret and a freshly generated nonce. Scoped to a single exchange session. Cannot be reused across sessions or parties.
AES-256-GCM
FIPS 197 / NIST SP 800-38D · Authenticated Encryption
Encrypts the hashed payload. GCM mode provides authenticated encryption — the recipient verifies ciphertext integrity before decryption, blocking any in-transit tampering.
HIPAA HIPAA Safe Harbor by design. No PHI crosses between parties. Only deterministic hashes.
FIPS FIPS-aligned primitives. SHA-256 (FIPS 180-4), AES-256-GCM (FIPS 197), HKDF-SHA256 (RFC 5869).
BAA BAA-compatible delivery. Audit log is tamper-evident and independently verifiable. No intermediary receives data.