There is described a method for transmitting synchronization messages, for example PTP messages of the IEEE 1588 standard, the PTP message being inserted into a data packet in line with the Internet Protocol, the data packet having an IP header, and the data packet having a UDP header. In this case, for the encrypted transmission on the PTP message, the data packet is addressed to a UDP port that is reserved for encrypted PTP messages, the data packet is provided with an additional S-PTP header that is provided for encryption, the PTP message is extended with a pseudo random number, and the PTP message is encrypted together with the pseudo random number.