> ## Documentation Index
> Fetch the complete documentation index at: https://docs.opaque.cash/llms.txt
> Use this file to discover all available pages before exploring further.

# Provable reputation (PSR)

> Privacy-preserving attestations bound to stealth identities and Groth16 verification.

[PSR](https://github.com/opaquecash/spec/blob/main/PSR.md) (Provable Stealth Reputation) lets issuers attest facts about a **stealth identity** without learning the recipient's public address. Recipients discover traits via their scanner and prove them with zero-knowledge.

## V2 model

| On-chain object  | Purpose                                                                                |
| ---------------- | -------------------------------------------------------------------------------------- |
| **Schema**       | Defines attestation fields (`bool passed, u64 score`), revocability, optional resolver |
| **Attestation**  | Binds field values to a `stealth_address_hash` (32-byte commitment)                    |
| **Announcement** | Optional discovery marker so the recipient's WASM scanner finds the trait              |

Schemas and attestations return chain-neutral `SchemaV2` / `AttestationV2` shapes from both Ethereum and Solana.

<Note>
  Schema registration and attestation **issuance** run on Ethereum and Solana only. Proof **verification and gating** extend further: the Groth16 verifier, `OpaqueReputationVerifierV2`, and the `PsrGate` credential-gated-entry contract are also deployed on Starknet, so proofs from the same trusted setup verify identically on all three chains (via `@opaquecash/psr-chain-starknet`). See [Starknet](/concepts/starknet) for the verification path and its testnet-preview caveats.
</Note>

## Issuer flow

```mermaid theme={"dark"}
sequenceDiagram
  participant Issuer
  participant SDK as OpaqueClient
  participant Chain as SchemaRegistry / AttestationEngine
  participant Announcer as StealthAddressAnnouncer

  Issuer->>SDK: createSchema(chain, params)
  SDK->>Chain: registerSchema
  Issuer->>SDK: issueAttestation(chain, { schemaId, recipient, fieldValues })
  SDK->>Chain: attest(stealth_address_hash, encoded data)
  SDK->>Announcer: announce (if meta-address recipient)
```

## Recipient flow

```mermaid theme={"dark"}
sequenceDiagram
  participant Recipient
  participant SDK as OpaqueClient
  participant Verifier as OpaqueReputationVerifier

  Recipient->>SDK: fetch native announcements
  Recipient->>SDK: discoverTraitsV2(rows, { chain })
  Recipient->>SDK: generateReputationProof({ trait, externalNullifier })
  Recipient->>SDK: submitReputationVerification(chain, args)
  SDK->>Verifier: verifyReputation (consumes nullifier)
```

## Recipient formats

`issueAttestation` accepts:

| Format                        | Example                  | Announce?                          |
| ----------------------------- | ------------------------ | ---------------------------------- |
| meta-address (66- or 98-byte) | `0x` + 132/196 hex chars | Yes (default)                      |
| 20-byte stealth address       | EVM address              | Resolves to hash                   |
| 32-byte hash                  | `stealth_address_hash`   | No ephemeral key, announce skipped |

## Action scopes and nullifiers

Proofs are scoped to a specific action via `externalNullifier`:

```ts theme={"dark"}
import { buildActionScope, externalNullifierFromScope } from "@opaquecash/opaque";

const scope = buildActionScope({
  chainId: 11155111,
  module: "my-dapp",
  actionId: "gate-v1",
});
const externalNullifier = externalNullifierFromScope(scope);
```

The same trait + scope can only be verified once (nullifier consumed on-chain).