> For the complete documentation index, see [llms.txt](https://docs.vida.id/identity-stack/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.vida.id/identity-stack/authentication/authentication-factors/cryptographic-token-pki/integration-methods/sdk/ios-development-kit/initializing-the-framework.md).

# Initializing the Framework

CredentialServicesKit establishes authentication with the VIDA Auth Credential Services by utilizing a bearer token. Please refer to acquire bearer token flow at API [authentication](/identity-stack/authentication/authentication-factors/cryptographic-token-pki/integration-methods/api/authentication.md) to generate a bearer token. For updating framework with the bearer token, developers can use the `VIDACredentialServicesProvider.shared.updateToken(token: String)` method.

By invoking the `updateToken` method and providing the valid bearer token as a parameter, the framework establishes the necessary authentication credentials

{% hint style="info" %}

* The bearer token expires in 300 seconds. 
* An expired token used for device registration shall return an error code 20018.
* Signatures can be generated even when the token has expired.
  {% endhint %}