Abstract: The method is for a secret communication between a transmitting unit and a receiving unit. The first time any message is sent from the transmitting unit (1) to the receiving unit (2), the units are synchronized, The transmitting unit (1) generates a public key (16) and a first security key (17a). A message (15) is encrypted using the public key and the first security key (17a). The encrypted message (18) and the public key (16) are sent via a transmitting medium (3). The first security key (17a) is not sent to the receiving unit (2). Upon receipt, the receiving unit generates a second security key (17b) that is identical to the first security key (17a). The receiving unit decrypts the message (18) to the readable message (15) using the public key (16) and the second security key (17b).