Checking the integrity of an electronic device

A method for checking an integrity of an electronic device, the electronic device comprising:

• a secure element, capable of storing and managing data and onto which a public key has been loaded, and intended for verifying an electronic signature, wherein the electronic signature was initially produced during a preliminary configuration phase of the electronic device,
• a processor configured to collaborate with the secure element, and
• a means of storing data, comprising a memory whose entire content has been initially authenticated and whose integrity can be verified using the public key, the memory comprising a code executable by the processor,
• wherein:
• in response to a request from the processor when the device is started, the secure element performs, on the entire content of the memory of the data storage means received through the processor, an authentication check of the entire content of the memory, in order to check, using the public key, that the entire content has not been modified since the initial authentication, the device being considered to be integral by the secure element when the authentication check has been successful,
• the secure element stores a reference time interval T which is configured to be less than a maximum time required for the secure element to recover, through the processor, the entire content of the memory to be authenticated,
• the authentication check of the entire content of the memory includes the following successive steps performed by the secure element and repeated until the entire content of the memory has been received:
• sending to the data storage means, through the processor, a request to send one or more sequences of data extracted from the memory,
• measuring a time which elapses between sending the request and receipt of the sequence or sequences requested, and comparing the time with the reference time interval T, and
• if the elapsed time is greater than the reference time interval T, refusing to authenticate the entire content of the memory of the data storage means and interrupting execution of the subsequent steps of the authentication check.