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Opaque Protocol is documented in the opaquecash/spec repository. The SDK implements these three layers:

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CSAP: Confidential Stealth Address Protocol

EIP-5564 stealth addresses with Opaque’s DKSAP key derivation (opaque-cash-v1 HKDF).
  • Meta-address registry
  • Stealth address announcer
  • View-tag prefilter + WASM ownership scan
Spec: CSAP.md SDK surface: Stealth API, Stealth payments concept

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PSR: Provable Stealth Reputation

Schema registry, attestation engine, and Groth16 reputation verifier. Attestations bind to stealth_address_hash, not a public EOA.
  • V2 schemas with ABI-style field definitions
  • Delegated issuance (up to 10 delegates)
  • Discovery announcements with attestation metadata
  • ZK proofs scoped by externalNullifier
Spec: PSR.md SDK surface: PSR API, PSR concept

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UAB: Universal Announcement Bus

Cross-chain relay of 96-byte stealth announcement payloads over Wormhole.
  • UABSender.announceWithRelay on source chain
  • UABReceiver re-emits on destination chain
  • Off-chain relayer delivers VAAs
Spec: UAB.md SDK surface: Cross-chain API, Cross-chain concept

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Repositories

RepoRole
opaquecash/sdkTypeScript SDK (@opaquecash/opaque)
opaquecash/specProtocol specifications
opaquecash/ethereumEVM contracts
opaquecash/solanaSolana programs
opaquecash/relayerUAB VAA relayer
opaquecash/scannerRust cryptography crate: WASM scanner for browsers, plus a universal scanner with Ethereum/Solana JSON-RPC adapters behind the native cargo feature for Rust wallets