System and method for secure communication of components inside self-service automats

A system for securing communication of components inside self-service automats comprising:

• a plurality of components, inside a self-service automat, including a first component and a second component, the first component being a transmitter in communication with the second component, being a receiver, wherein the first and second components are on a bus system;
• a plurality of configured computing units, including a first computing unit in communication with the first component and a second computing unit in communication with the second component;
• and
• the bus system having a transport layer, wherein data are exchanged between the first component and the second component as tuples, wherein
• C are message data M encrypted with an encryption key,
• A are message data M authenticated with an authentication key,
• R represents a participant role of a component on the bus system, wherein R includes active and passive,
• N represents a message counter, and
• Z represents a session counter,
• wherein the second computing unit:
• determines whether Z is less than a maximum session counter Zmax;
• determines whether N is less than a maximum message counter Nmax;
• compares a tuple ({circumflex over (Z)},{circumflex over (N)}) to a tuple ( Z, N), wherein {circumflex over (Z)} is a session counter for Δ-last messages, {circumflex over (N)} is a message counter for Δ-last messages, Z is a last session counter, and N is a last message counter;
• generates, based on the comparison, an error if more than Δ messages have been lost;
• decrypts message data, based on the comparison, if not more than Δ messages have been lost;
• and
• upon the decryption of the message data, authenticates the decrypted message data;
• wherein the second computing unit decrypts the message data based on KdecR and C, where KdecR is a result of a key generation procedure using a common key K;
• and
• wherein the second computing unit authenticates the decrypted message data, based on a comparison of A and A′, if A is equal to A′, wherein A′ is determined based on KverR, N, the decrypted message data, and |C|, wherein KverR is a result of a key generation procedure using a common key K.