# AuthDescriptorValidationService · FT4 TypeScript client · Chromia Docs (concept)

> Interface used by auth descriptor validation to fetch dynamic parameters from blockchain interface AuthDescriptorValidationService { getAuthDescriptorCount

Source: https://docs.chromia.com/pages/ft4-ts-client/interfaces/accounts.AuthDescriptorValidationService/

Interface

# AuthDescriptorValidationService

On this page

* [Properties](#properties)
* [getAuthDescriptorCounter](#getauthdescriptorcounter)
* [getBlockHeight](#getblockheight)

Interface used by auth descriptor validation to fetch dynamic parameters from blockchain

```signature
interface AuthDescriptorValidationService {
    getAuthDescriptorCounter: (
        accountId: BufferId,
        authDescriptorId: BufferId,
    ) => Promise<number | null>;
    getBlockHeight: () => Promise<number>;
}
```

## Properties

### getAuthDescriptorCounter

```signature
getAuthDescriptorCounter: (
    accountId: BufferId,
    authDescriptorId: BufferId,
) => Promise<number | null>
```

Gets auth descriptor counter for provided account and auth descriptor

#### Type Declaration

* ```signature
  (accountId: BufferId, authDescriptorId: BufferId): Promise<number | null>
  ```

  + #### Parameters

    - accountId: BufferId

      The account id to get counter for
    - authDescriptorId: BufferId

      The id of the auth descriptor to get counter for

    #### Returns Promise<number | null>

    auth descriptor counter or null

### getBlockHeight

```signature
getBlockHeight: () => Promise<number>
```

Gets block height

#### Type Declaration

* ```signature
  (): Promise<number>
  ```

  + #### Returns Promise<number>

    block height

[View this page on docs.chromia.com](https://docs.chromia.com/pages/ft4-ts-client/interfaces/accounts.AuthDescriptorValidationService.html)Generated API reference, mirrored from the live docs