Token
Tokens are handled completely in the background by the SDKs. Whenever the Reader needs a new token, the only requirement is a working internet connection at that time.
What are tokens?
Tokens are a technical requirement to perform measurements with a Reader. The tokens will be
fetched automatically from the M-Trust™ backend. Each token has a limited amount of scans that can
be performed with it. The amount of scans in a token can be configured in the SDK and can be
different for each token leasing if needed. The requested scan amount can be set with
setTokenAmount(int amount) in the corresponding Reader object in the SDK.
Please note, that the maximum allowed number of scans per token is limited in the backend.
The amount of scans left with an installed token will be returned from the prime function
in the UrpPrimeResponse.active field and is displayed in the default UI. You can also request
the installed token via the SDK on your own.
Why does the Reader need tokens?
A token is basically just a unique serial number paired with a number of allowed scans per serial number. The combination of unique serial number and the number of the individual scan creates a unique identifier for each scan. M-Trust™ uses this unique identifier besides other mechanisms to make your scan secure and protected against common attack vectors such as replay attacks.
Once a Reader consumed all the scans in the installed token, it can no longer perform any scans unless a new token was leased. In cases where no internet connection is available, the Reader will disable once all scans are used and can no longer perform scans. Try to establish an active internet connection and prime the Reader again. It will then automatically lease a new token.