# Overview and Background

To maintain the Root of Trust, the secure bootloader only lets you program the device if you prove that you are allowed to do so. A challenge and response process matches certificates; if you do not have a matching certificate, it is not possible for you to program the device.

Part of attestation is the Entity Attestation Token (EAT), which contains claims that are generated in the device RoT. EAT token generation is expected to be performed many times, possibly for each transaction. It is relatively inexpensive because the claims data is small and ECDSA signing is relatively fast. For further details about the EAT, see Attestation Token.

The token is sent to the device, and then goes to the relying party, which then relays it (without examining or modifying it) to the attestation service for verification.