| CPC H04L 9/0891 (2013.01) [H04L 9/0637 (2013.01); H04L 9/0822 (2013.01); H04L 9/0825 (2013.01); H04L 9/14 (2013.01); H04L 47/12 (2013.01); H04L 63/0442 (2013.01)] | 8 Claims | 

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               1. A method for data transfer, which comprises the following steps of: 
            establishing a data connection with a connection key between a first communication partner and a second communication partner; 
                encrypting the connection key for the data connection by the first communication partner and/or by the second communication partner with an additional key; 
                sending a message containing an unencrypted part and a part encrypted with the connection key from the first communication partner to the second communication partner, wherein the unencrypted part of the message contains the connection key encrypted with the additional key; 
                wherein a third communication partner is intentionally participating as a listener in the data connection and the additional key is known to the third communication partner, said third communication partner being specifically included in the data connection by at least one of said first communication partner or said second communication partner, said third communication partner at least one of logging or inspecting the message on behalf of said at least one of said first communication partner or said second communication partner; and 
                decrypting, by the third communication partner, the connection key encrypted with the additional key from the unencrypted part of the message, so it is possible for the third communication partner to read the encrypted part of the message. 
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