Skip to main content
OpaqueClient in @opaquecash/opaque is the single integration surface for stealth payments, PSR admin, reputation proofs, and cross-chain announcements.

​
Construction

Pass the connected wallet(s) in the unified signer shape. The client prompts for the one-time SETUP_MESSAGE signature (or reuses a cached one), derives the stealth keys, and wires each wallet as that chain’s write signer: 
import { OpaqueClient } from "@opaquecash/opaque";

// Browser, Ethereum wallet
const client = await OpaqueClient.fromWallet({
  wallets: { chain: "ethereum", address: userAddress, provider: window.ethereum },
  chainId: 11155111,
  rpcUrl: "https://ethereum-sepolia-rpc.publicnode.com",
  wasmModuleSpecifier: "/pkg/cryptography.js",
});

// Both chains at once (Solana wallet-adapter + viem WalletClient)
const dual = await OpaqueClient.fromWallet({
  wallets: [
    { chain: "ethereum", address: userAddress, walletClient },
    { chain: "solana", publicKey, signMessage, signTransaction },
  ],
  chainId: 11155111,
  rpcUrl,
  solana: { cluster: "devnet" },
});
The FIRST wallet in the list signs SETUP_MESSAGE (key derivation) unless you pass a cached walletSignature, in which case no prompt happens at all: 
const restored = await OpaqueClient.fromWallet({
  wallets: [],                  // allowed when walletSignature is provided
  walletSignature: cachedSignature,
  chainId: 11155111,
  rpcUrl,
});
See Unified signer below for the wallet shapes.

​
OpaqueClient.create(config) (manual)

Use create when you already hold the setup signature and want to wire signers yourself: 
const client = await OpaqueClient.create(config);
create is async: it optionally loads WASM and derives viewing/spending keys from walletSignature.

​
OpaqueClient.createViewOnly(config, keys)

Build a scan-only client from the viewing private key and spending public key (no walletSignature). It scans and reads balances but cannot spend — sweep and key reconstruction throw. This is the safe shape for a server-side scanner. See Server-side scanning. 
const viewer = await OpaqueClient.createViewOnly(
  { chainId, rpcUrl, ethereumAddress, wasmModuleSpecifier },
  { viewingKey, spendPublicKey },
);
viewer.isViewOnly; // true

​
OpaqueClientConfig

FieldTypeRequiredDescription
chainIdnumberYesEVM chain id (11155111 Sepolia). Must be in getSupportedChainIds() unless contracts overridden.
rpcUrlstringYesHTTP RPC for EVM reads and sweep
walletSignatureHexYesHKDF entropy from the SETUP_MESSAGE signature; never sent on-chain
ethereumAddressAddressYesConnected EOA (registrant context, PSR issuer on EVM)
wasmModuleSpecifierstringNo*URL to cryptography.js. *Required for scan/sweep/prove
trackedTokensTrackedToken[]NoExtra ERC-20s for balance aggregation
contractsPartial<{...}>NoOverride registry, announcer, verifier, UAB addresses
solanaSolanaAdapterConfigNo****Required when scanning/sending on Solana
ethereumProviderEIP1193ProviderNo******For EVM writes if no ethereumWalletClient
ethereumWalletClientWalletClientNo***Precedence over provider for EVM writes
solanaWallet{ publicKey, signTransaction }No********Required for Solana writes
ens{ client?, getText? }NoENS read access for resolveRecipient of *.eth names (an ENS-capable viem client, or a custom text-record reader)
ipfs{ gateways?, fetch? }NoGateway list + fetch override for resolveRecipient of ipfs:// DID documents
ons{ parentName?, registry?, mirrorProgram? }NoONS overrides for *.opq.eth-style names; defaults from @opaquecash/deployments (testnet parent opqtest.eth)
sns{ getRecord? }NoCustom .sol record reader; defaults to the Records V2 TXT reader over the solana connection

​
Unified signer

UnifiedSigner is one shape over every supported wallet type. Pass it to fromWallet, or use requestSetupSignature directly when you manage sessions yourself: 
import { requestSetupSignature, type UnifiedSigner } from "@opaquecash/opaque";

// Ethereum: EIP-1193 provider or a viem WalletClient
const eth: UnifiedSigner = { chain: "ethereum", address, provider: window.ethereum };
const ethViem: UnifiedSigner = { chain: "ethereum", address, walletClient };

// Solana: wallet-adapter shape
const sol: UnifiedSigner = { chain: "solana", publicKey, signMessage, signTransaction };

const signature = await requestSetupSignature(eth);  // personal_sign over SETUP_MESSAGE
FieldEthereumSolana
IdentityaddresspublicKey (base58 string or PublicKey)
Setup signatureprovider (personal_sign) or walletClientsignMessage
Transaction signingsame provider / walletClientsignTransaction

​
Static helpers

MethodReturnsDescription
OpaqueClient.supportedChainIds()number[]Bundled EVM chain ids
OpaqueClient.chainDeployment(chainId)OpaqueChainDeployment | undefinedContract addresses + default tokens
OpaqueClient.buildReputationActionScope({ chainId, module, actionId })stringAction scope string
OpaqueClient.reputationExternalNullifierFromScope(scope)bigintCircuit external nullifier

​
Method index

Stealth API

Registry, recipient resolution, send, scan, sweep, anonymity utilities

PSR API

Schemas, attestations, delegates

Reputation API

Traits, proofs, verifier

Cross-chain API

UAB relay and cross-chain scan

React hooks

OpaqueProvider, useScan, useStealthBalance

Utilities

Exported helpers, types, adapters

​
Instance getters

client.getChainId()           // number
client.getEthereumAddress()   // Address
client.getMetaAddressHex()    // Hex, the 66-byte meta-address
client.getContracts()         // { stealthMetaAddressRegistry, stealthAddressAnnouncer, opaqueReputationVerifier? }

​
Signer requirements summary

CategoryMethodsEthereum signerSolana signerWASM
Read-only stealthresolveRecipient, resolveRecipientMetaAddress, isMetaAddressRegisterednosolana for Solana checkno
Stealth writesregisterMetaAddress, sendStealthPaymentyesyesno
Scan / sweepscan, sweep, filterOwnedAnnouncements, balancesnosolanayes
PSR admincreateSchema, issueAttestation, …yes (EVM)yes (Solana)no
ReputationdiscoverTraitsV2, discoverTraits (legacy V1), generateReputationProof, submitReputationVerificationyes (submit EVM)yes (submit Solana)yes

​
Error: WASM not configured

If wasmModuleSpecifier is omitted and you call a WASM-backed method: 
Opaque: this method requires the cryptography WASM module. Pass `wasmModuleSpecifier` to OpaqueClient.create.
PSR admin methods work without WASM.