Authentication

This guide explains how to securely and efficiently authenticate Caf SDKs.

Integration overview

1. Obtain access credentials (Mobile Key)

2. Generate the Authentication Token (JWT signed with your client-secret)

3. Exchange this token for a Mobile Token (Session Token)

4. Use the Mobile Token when initializing the SDK

For clients using Caf SDKs who subsequently create transactions to perform additional validations, you will have an additional step: link the Mobile Token to a transaction, sending it as a referenceToken in the creation request to allow complete tracking of the user journey. Check out Transaction linking for more details.

1. Obtain access credentials (Mobile Key)

Mobile Keys are used to sign and authenticate requests.

How to obtain:

1. Go to the Trust Platform

2. Navigate to Settings → API configurations (Mobile Keys "tab")

3. Copy an existing key or create a new one, specifying the products and key name.

2. Generate Authentication Token (JWT)

This JWT is generated on your server and signed with the Mobile Key's client-secret.

Payload fields:

Field	Required	Description
iss	Yes	Your client-id (provided by CAF)
exp	No	Token expiration (Unix timestamp)

Example payload:

{
  "iss": "your-client-id",
  "exp": 1728000000
}

This JWT must be signed with the Mobile Key's client-secret.

3. Exchange Authentication Token for Mobile Token

After generating the JWT, you must exchange it for the Mobile Token, which will be used to initialize the SDK. For each SDK session in your application, generate a Mobile Token using the previously created Authentication Token.

Generate Mobile Token (Session Token)

get

Returns a JWT token enriched with a unique session identifier.

Authorizations

Responses

200

JWT generated with session details

application/json

401

Invalid or missing token

application/json

500

Internal server error

application/json

get

HTTPcURL

GET /bff/session-tokens HTTP/1.1
Host: web.us.prd.caf.io
Authorization: YOUR_AUTHENTICATION_TOKEN

{
  "requestId": "123e4567-e89b-12d3-a456-426614174000",
  "sessionToken": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
}

4. Use the Mobile Token in the SDK

The mobile-token (Session Token) is used during SDK initialization and ensures that each session is securely authenticated and traceable.

Below is how to integrate it on different platforms:

iOS

let builder = CafSdkProvider.Builder(
    mobileToken: "mobile-token",
    ...
)

Check out iOS SDK Integration for more details.

Android

val builder = CafSdkProvider.Builder(
    mobileToken = "mobile-token",
    ...
).build()

Check out Android SDK Integration for more details.

Web

const builder = await CafSdkProvider.initializeSdk(
  "mobile-token",
  ...
);

Check out Web SDK Integration for more details.

Transaction linking

To ensure the security and complete traceability of the user journey, each transaction created via the API must be linked to the original session generated by the SDK. This link is made by including the Mobile Token (session token) in your calls, creating a unified audit trail.

See Transaction linking for more details.

Best practices for token-based authentication

To ensure a secure and reliable integration when using token-based authentication with our SDK, follow these recommended practices and avoid common pitfalls.

✅ Recommended practices

Practice	Description
Generate and sign tokens on the server	Always issue JWTs from your trusted backend system to avoid exposing signing keys.
Exchange JWTs using /session-tokens before SDK initialization	Use our secure /session-tokens endpoint to obtain short-lived session tokens.
Use short expiration times for JWTs	Minimize the window for token misuse in case of interception. Tokens should typically expire within a few minutes.
Validate SDK responses on your backend using the client-secret	Always verify responses server-side to ensure integrity and authenticity.
Use HTTPS for all communications	Prevent man-in-the-middle attacks and ensure encryption in transit.
Rotate secrets periodically	Regularly rotate your signing keys and client-secret to reduce exposure risks.
Monitor token usage and behavior	Implement logging and monitoring to detect abnormal or suspicious activity.

❌ Unsafe practices

Practice	Risk
Generating tokens on the frontend	Exposes your signing keys and compromises the entire authentication system.
Storing signing keys or secrets in frontend/mobile apps	Secrets in client-side code can be extracted and misused.
Using long-lived tokens	Increases the window of vulnerability in case of leakage.
Skipping token validation on the backend	Opens up the system to forged or tampered tokens.
Hardcoding secrets in version-controlled code	Secrets in code repositories can be leaked or accessed by unauthorized users.

Security tip

Never expose your secrets, private keys, or JWT signing credentials on the client-side. Always treat tokens and secrets as sensitive data and follow the principle of least privilege.