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

# Credentials

> Retrieve, verify, and present W3C Verifiable Credentials and SD-JWT selective disclosures

## Overview

The `Credentials` service manages W3C Verifiable Credentials and SD-JWT selective disclosures. Retrieve individual credentials, list with filters, verify credential JWTs, and create selective-disclosure presentations.

## Get

Retrieve a single Verifiable Credential by its ID.

```go theme={null}
vc, err := client.Credentials.Get(ctx, "vc_01HXYZ...")
if err != nil {
    log.Fatal(err)
}
fmt.Printf("ID: %s\n", vc.ID)
fmt.Printf("Type: %v\n", vc.Type)
fmt.Printf("Issuer: %s\n", vc.Issuer)
fmt.Printf("Subject: %s\n", vc.Subject)
fmt.Printf("Status: %s\n", vc.Status)
```

### Parameters

| Parameter      | Type     | Required | Description                       |
| -------------- | -------- | -------- | --------------------------------- |
| `credentialID` | `string` | Yes      | The unique credential identifier. |

### Response (`VerifiableCredential`)

| Field            | Type             | Description                                                  |
| ---------------- | ---------------- | ------------------------------------------------------------ |
| `ID`             | `string`         | Unique credential identifier.                                |
| `Type`           | `[]string`       | Credential types (always includes `"VerifiableCredential"`). |
| `Issuer`         | `string`         | DID of the credential issuer.                                |
| `Subject`        | `string`         | DID of the credential subject (the holder).                  |
| `IssuanceDate`   | `string`         | ISO 8601 timestamp when the credential was issued.           |
| `ExpirationDate` | `*string`        | ISO 8601 expiration timestamp, or `nil` if no expiry.        |
| `Status`         | `string`         | Current status: `"active"`, `"revoked"`, or `"expired"`.     |
| `JWT`            | `string`         | The credential in compact JWT format.                        |
| `Claims`         | `map[string]any` | The credential subject claims.                               |

## List

List Verifiable Credentials with optional filters.

```go theme={null}
result, err := client.Credentials.List(ctx, grantex.ListCredentialsParams{
    PrincipalID: grantex.String("user_abc123"),
    Type:        grantex.String("IdentityCredential"),
    Status:      grantex.String("active"),
    Page:        grantex.Int(1),
    PageSize:    grantex.Int(20),
})
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Total: %d\n", result.Total)
for _, vc := range result.Credentials {
    fmt.Printf("  %s: %v\n", vc.ID, vc.Type)
}
```

### Parameters

| Parameter     | Type      | Required | Description                                               |
| ------------- | --------- | -------- | --------------------------------------------------------- |
| `PrincipalID` | `*string` | No       | Filter credentials by principal (subject) ID.             |
| `Type`        | `*string` | No       | Filter by credential type (e.g., `"IdentityCredential"`). |
| `Status`      | `*string` | No       | Filter by status: `"active"`, `"revoked"`, `"expired"`.   |
| `Page`        | `*int`    | No       | Page number for pagination (default: 1).                  |
| `PageSize`    | `*int`    | No       | Results per page (default: 20, max: 100).                 |

### Response (`ListCredentialsResponse`)

| Field         | Type                     | Description                             |
| ------------- | ------------------------ | --------------------------------------- |
| `Credentials` | `[]VerifiableCredential` | Slice of Verifiable Credential objects. |
| `Total`       | `int`                    | Total number of matching credentials.   |

## Verify

Verify a Verifiable Credential JWT. Checks signature, expiration, revocation status, and issuer trust chain.

```go theme={null}
result, err := client.Credentials.Verify(ctx, vcJWT)
if err != nil {
    log.Fatal(err)
}
if result.Valid {
    fmt.Printf("Issuer: %s\n", *result.Issuer)
    fmt.Printf("Subject: %s\n", *result.Subject)
    fmt.Printf("Claims: %v\n", result.Claims)
} else {
    fmt.Printf("Invalid: %s\n", *result.Reason)
}
```

### Parameters

| Parameter | Type     | Required | Description                                      |
| --------- | -------- | -------- | ------------------------------------------------ |
| `vcJWT`   | `string` | Yes      | The Verifiable Credential in compact JWT format. |

### Response (`VerifyCredentialResponse`)

| Field       | Type             | Description                                                                                   |
| ----------- | ---------------- | --------------------------------------------------------------------------------------------- |
| `Valid`     | `bool`           | Whether the credential is valid.                                                              |
| `Issuer`    | `*string`        | DID of the issuer (if valid).                                                                 |
| `Subject`   | `*string`        | DID of the subject (if valid).                                                                |
| `Claims`    | `map[string]any` | Credential subject claims (if valid).                                                         |
| `ExpiresAt` | `*string`        | ISO 8601 expiration timestamp.                                                                |
| `Reason`    | `*string`        | Reason for invalidity: `"expired"`, `"revoked"`, `"invalid_signature"`, `"untrusted_issuer"`. |

## Present

Create a selective-disclosure presentation from an SD-JWT. Only the specified claims are disclosed.

```go theme={null}
presentation, err := client.Credentials.Present(ctx, grantex.PresentCredentialParams{
    SDJWT:           "eyJ0eXAiOiJ2YytzZC1qd3QiLC...",
    DisclosedClaims: []string{"name", "email"},
    Audience:        grantex.String("did:web:verifier.example.com"),
    Nonce:           grantex.String("unique-request-nonce"),
})
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Presentation JWT: %s\n", presentation.PresentationJWT)
fmt.Printf("Disclosed: %v\n", presentation.DisclosedClaims)
```

### Parameters

| Parameter         | Type       | Required | Description                                          |
| ----------------- | ---------- | -------- | ---------------------------------------------------- |
| `SDJWT`           | `string`   | Yes      | The SD-JWT credential to create a presentation from. |
| `DisclosedClaims` | `[]string` | Yes      | Claim names to disclose. All others remain hidden.   |
| `Audience`        | `*string`  | No       | Intended verifier DID or URL for the holder binding. |
| `Nonce`           | `*string`  | No       | Nonce for replay protection in the holder binding.   |

### Response (`PresentCredentialResponse`)

| Field             | Type       | Description                                             |
| ----------------- | ---------- | ------------------------------------------------------- |
| `PresentationJWT` | `string`   | The SD-JWT presentation with only the disclosed claims. |
| `DisclosedClaims` | `[]string` | The claim names that were disclosed.                    |
| `HolderBinding`   | `string`   | The key binding JWT proving holder possession.          |