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.