Method of managing an emergency mode transaction procedure, and an associated device

A non-transitory computer readable data medium storing a computer program comprising instructions that, when executed by a processor of an electronic device, perform a method for managing an emergency procedure of an emergency transaction mode that can be activated in the event of a computer attack on or a failure of a transaction network, the method comprising:

• receiving an activation command for activating the emergency procedure, the activation command comprising an identifier of the emergency procedure and first encrypted data;
• verifying the activation command, including verifying the first encrypted data;
• if verification of the activation command is successful, activating the emergency procedure;
• after activating the emergency procedure and after initializing a transaction between the electronic device and a reader, sending a message to the reader, the message comprising a consultation request to consult a normal mode server of the transaction network;
• and
• upon receiving a message indicating that consultation of the normal mode server has failed, sending a cryptogram to the reader, the cryptogram comprising at least one information element about said emergency procedure.