A method for sending recorded, secured messages via a messaging system to a receiving device to be tested, the messages being sent by means of message packets, the method comprising the following steps: • providing first secured messages for processing in a playback unit, the first messages comprising a payload, a first counter value, and a first authenticator, characterized in that the following information is provided to the playback unit: o at least parts of a communication description for the receiving device to be tested or an algorithm for data interpretation, o a second counter value for the receiving device to be tested, wherein the second counter value is provided by the current counter value known to the test environment for the receiving device to be tested in each case, or wherein the second counter value is provided by a counter value specified by a user or by an automatically calculated counter value, o information for encrypting and a corresponding key • by means of the playback unit: o removing the first authenticator and the first counter value from the first secured messages by using the communication description or by using information obtained by means of the algorithm for data interpretation ∘ creating second secured messages by adding the second counter value in each case and creating and adding a second authenticator in each case by using the second counter value, the information for encrypting, and the key, and by using the communication description or the information obtained by means of applying the algorithm for data interpretation, • sending the second secured messages to the receiving device to be tested. • providing first secured messages for processing in a playback unit, the first messages comprising a payload, a first counter value, and a first authenticator, characterized in that the following information is provided to the playback unit: o at least parts of a communication description for the receiving device to be tested or an algorithm for data interpretation, o a second counter value for the receiving device to be tested, wherein the second counter value is provided by the current counter value known to the test environment for the receiving device to be tested in each case, or wherein the second counter value is provided by a counter value specified by a user or by an automatically calculated counter value, o information for encrypting and a corresponding key o at least parts of a communication description for the receiving device to be tested or an algorithm for data interpretation, o a second counter value for the receiving device to be tested, wherein the second counter value is provided by the current counter value known to the test environment for the receiving device to be tested in each case, or wherein the second counter value is provided by a counter value specified by a user or by an automatically calculated counter value, o information for encrypting and a corresponding key • by means of the playback unit: o removing the first authenticator and the first counter value from the first secured messages by using the communication description or by using information obtained by means of the algorithm for data interpretation ∘ creating second secured messages by adding the second counter value in each case and creating and adding a second authenticator in each case by using the second counter value, the information for encrypting, and the key, and by using the communication description or the information obtained by means of applying the algorithm for data interpretation, o removing the first authenticator and the first counter value from the first secured messages by using the communication description or by using information obtained by means of the algorithm for data interpretation ∘ creating second secured messages by adding the second counter value in each case and creating and adding a second authenticator in each case by using the second counter value, the information for encrypting, and the key, and by using the communication description or the information obtained by means of applying the algorithm for data interpretation, • sending the second secured messages to the receiving device to be tested.