Abstract: A method for applying control to a vehicle. The method includes: receiving, by way of a second control unit of a second vehicle to which control is to be applied, a signal encompassing a message encrypted using a valid symmetrical key of a first control unit of a first vehicle; ascertaining, by way of the second control unit, a decryptability of the encrypted message using a valid symmetrical key of the second control unit or a symmetrical reserve key of the second control unit ascertained by way of the second control unit; ecrypting the encrypted message, depending on the ascertained decryptability, by way of the second control unit using the valid symmetrical key of the second control unit or the symmetrical reserve key of the second control unit; and applying control, based on the decrypted message, to the second vehicle to which control is to be applied.

Abstract: A method for authenticating a user terminal as a transmitter of a message transmitted in a wireless communication network having a plurality of spatially distributed user terminals, The message is transmitted from a first user terminal to at least one second and/or one third user terminal with the aid of a wireless communications connection. The message includes useful data, first user-terminal-specific and second user-terminal-specific authentication data. The first user terminal is authenticated as the transmitter of the message based on the first user-terminal-specific authentication data with the aid of the second user terminal, and/or based on the second user-terminal-specific authentication data with the aid of the third user terminal.

Abstract: A method for applying control to a vehicle. The method includes: receiving, by way of a second control unit of a second vehicle to which control is to be applied, a signal encompassing a message encrypted using a valid symmetrical key of a first control unit of a first vehicle; ascertaining, by way of the second control unit, a decryptability of the encrypted message using a valid symmetrical key of the second control unit or a symmetrical reserve key of the second control unit ascertained by way of the second control unit; ecrypting the encrypted message, depending on the ascertained decryptability, by way of the second control unit using the valid symmetrical key of the second control unit or the symmetrical reserve key of the second control unit; and applying control, based on the decrypted message, to the second vehicle to which control is to be applied.