Core concepts
| Term | Definition |
|---|---|
| Stealth address | A one-time destination derived by the sender from the recipient’s meta-address. Each payment creates a fresh one. |
| Meta-address | The recipient’s public profile containing spending_pk and viewing_pk. Published once, used by all senders. |
| Announcement | A public record containing the encrypted shared secret (ciphertext) and view tag. Lets the recipient find their payment. |
| View tag | A 1-byte value derived from the shared secret. Filters out ~99.6% of irrelevant announcements during scanning. |
Cryptography
| Term | Definition |
|---|---|
| ML-KEM-768 | Module Lattice-based Key Encapsulation Mechanism. NIST FIPS 203. The post-quantum algorithm SPECTER uses for sender-recipient shared secrets. |
| Encapsulation | The sender’s operation: takes a public key, produces a ciphertext and shared secret. |
| Decapsulation | The recipient’s operation: takes the ciphertext and secret key, recovers the shared secret. |
| SHAKE-256 | A NIST-standardized extendable-output hash function. Used in SPECTER for key derivation with domain separation. |
| MLWE | Module Learning With Errors. The mathematical hard problem underlying ML-KEM’s security. No quantum algorithm solves it efficiently. |
| secp256k1 | The elliptic curve used by Ethereum wallets. SPECTER’s current spend path derives a secp256k1 key for compatibility. |
| ML-DSA-65 | A post-quantum digital signature algorithm (FIPS 204). Planned for future SPECTER spending via smart accounts. |
Keys
| Term | Definition |
|---|---|
| spending_pk / spending_sk | The spending keypair. The public key is part of the meta-address. The shared secret + spending key determine the stealth address. |
| viewing_pk / viewing_sk | The viewing keypair. The sender encapsulates to viewing_pk. The recipient decapsulates with viewing_sk to discover payments. |
| eth_private_key | The derived secp256k1 private key returned by the scan endpoint. Used to spend from the stealth address in Ethereum wallets. |
Protocol
| Term | Definition |
|---|---|
| Registry | The announcement storage system. Either in-memory (dev) or Turso/libSQL (production). |
| Scanning | The process of checking announcements to find payments meant for you. Uses view tag filtering for efficiency. |
| Discovery | A confirmed match during scanning: a payment addressed to you, with the stealth private key recovered. |
Ecosystem
| Term | Definition |
|---|---|
| ERC-5564 | Ethereum standard for stealth addresses (schemeId 1 = classical ECDH). SPECTER proposes schemeId 2 (ML-KEM). |
| ERC-6538 | Ethereum standard for stealth meta-address registries. |
| ENS | Ethereum Name Service. Maps .eth names to meta-addresses via IPFS. |
| SuiNS | Sui Name Service. Maps .sui names to meta-addresses. |
| Yellow Network | State channel network for off-chain trading. SPECTER integrates to provide private channels. |
| ERC-4337 | Account abstraction standard. Enables custom signature verification, the path to PQ spending. |