A method of providing an authenticable time-and-location indication using a radio-navigation
signal receiver comprises receiving radio-navigation signals broadcast from a plurality of radio-navigation
signal sources, at least some of the radio-navigation signals containing one or more cryptographic tokens protected by
encryption, the cryptographic tokens being updated from time to time. The
receiver retrieves, by decryption, the cryptographic tokens from the radio-navigation signals containing them. The
receiver then determines positioning data, representing its geographical position and time, based on the radio-navigation signals received. The receiver generates a digital
authentication code using a cryptographic function taking as inputs at least the positioning data and the retrieved cryptographic tokens, and produces a data
package including a first part containing the positioning data and a second part containing the digital
authentication code.