SPECTER: Stealth Post quantum enabling Cryptographic Transaction Engine for Routing
Every transaction on a public blockchain is a permanent, queryable record. Counterparties, balances, and payment patterns are exposed to anyone — retroactively and indefinitely.
The existing privacy layer for Ethereum — stealth addresses, as implemented in Umbra, Fluidkey, and ERC-5564 — relies on ECDH over secp256k1. Shor's algorithm, running on a sufficiently capable quantum computer, breaks ECDH entirely. The implication is not a future problem: nation-state adversaries are actively archiving public blockchain data today under the assumption that they can decrypt it once the hardware exists. This is the "harvest now, decrypt later" threat.
"Store now, decrypt later attacks mean data encrypted today may be vulnerable tomorrow." — CISA / NSA Joint Advisory, 2022
NIST finalized its post-quantum cryptography standards in 2024 (FIPS 203). The window to migrate classical cryptographic systems is open now. Payment history that users consider private today may not remain so.
SPECTER replaces ECDH in the stealth address construction with ML-KEM-768 (NIST FIPS 203), the standardized post-quantum key encapsulation mechanism. The protocol preserves the same user experience — a sender pays to a human-readable name, the recipient scans to discover what's theirs — while making the underlying privacy guarantees quantum-resistant by construction.