Granted Patent B2

US 8,787,569 · App. 12/603,836 · Granted Jul 22, 2014

Abstract

Claims (61)

1. A method for securing communication of components inside a self-service automat that are connected to each other by a bus system, with a transmitter and a receiver, comprising:

exchanging data as tuples (C, A, R, N, Z) between the transmitter and the receiver on a transport layer of the bus system, 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 of active or passive participants,

N represents a message counter, and

Z represents a session counter,

determining while transmitting from the transmitter to the receiver, whether Z is less than a maximum session number Z max ;

determining whether N is less than a maximum message number N max ;

comparing a tuple ({circumflex over (Z)},{circumflex over (N)}) to a tuple ( Z , N ), wherein {circumflex over (Z)} is a session number for Δ-last messages, {circumflex over (N)} is a message number for Δ-last messages, {circumflex over (Z)} is a last session counter, and N is a last message counter;

generating, based on the comparing, an error if more than Δ messages have been lost:

decrypting message data, based on the comparing, if not more than Δ messages have been lost;

upon decrypting the message data, authenticating the message data;

decrypting the message data based on a K dec R and C, wherein K dec R is a result of a key generation procedure using a common key K;

comparing A to an authentication value A′ at the receiver, wherein A′ is determined based on K ver R , N, the decrypted message data, and |C|, wherein K ver R is a result of a key generation procedure using a common key K; and

authenticating the decrypted message data, based on the comparing of A to A′, if A is equal to A′.

2. The method of claim 1 , further comprising:

exchanging data as a tuple (C, A, R, N, Z, {circumflex over (N)}, {circumflex over (Z)}) between the transmitter and the receiver on the transport layer of the bus system, where {circumflex over (N)} is a message counter for Δ-last messages N and {circumflex over (Z)} is a last session counter for Δ-last messages.

3. The method of claim 2 , further comprising:

allowing Δ-last messages to be lost during the exchanging the data without informing an application layer;

transmitting from the transmitter to the receiver, a pair ({circumflex over (Z)},{circumflex over (N)}) as a current session counter; and

upon the exchanging the data, enabling a check at the receiver.

4. The method of claim 1 , wherein the encryption key and the authentication key are a common key K, securely filed in the components, that was generated at the time of production and assembly of the self-service automat on a basis of certificates from a public key infrastructure (PKI).

5. The method of claim 4 , wherein the common key K is stored in a Trusted Platform Module (TPM).

6. The method of claim 1 , wherein A:=AUTH[K auth R , N, M, |M|], where K R auth is the result of a key generation procedure using a common key K.

7. The method from one or more of the preceding claims, further comprising:

determining, while transmitting from the transmitter to the receiver, whether the message counter N is less than a maximum message counter N max ;

and upon the determining whether N is less than N MAX , IF N is less than N MAX , setting N:=N+1.

8. The method of claim 1 , wherein the self-service automat is an automated banking machine.

9. The method of claim 1 or 6 , wherein C:=ENC[K enc R , Z, N, M], where K enc R is the result of a key generation procedure using a common key K.

10. The method of claim 1 , wherein the bus system is a universal serial bus (USB).

11. 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 Z max ;

determines whether N is less than a maximum message counter N max ;

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 K dec R and C, where K dec R 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 K ver R , N, the decrypted message data, and |C|, wherein K ver R is a result of a key generation procedure using a common key K.

12. The system of claim 11 , further comprising:

a means for exchanging a tuple (C, A, R, N, {circumflex over (N)}, {circumflex over (Z)}), between the first component and the second component, on the transport layer of the bus system, where {circumflex over (N)} is a message counter for Δ-last messages, and {circumflex over (Z)} is a last session counter for Δ-last messages.

13. The system of claim 12 , further comprising:

a means for allowing the Δ-last messages to be lost in a transmission, from the first component to the second component, without informing an application layer above, wherein the first component transmits a current session counter pair (N, Z) and a pair ({circumflex over (N)},{circumflex over (Z)}) so that a check is enabled at the receiver.

14. The system of claim 13 , further comprising:

a means for generating and securely filing a common key K during the production and assembly of the self-service automat on the basis of certificates from a public key infrastructure (PKI), wherein a calculating unit uses the common key K for at least one of authentication and encryption.

15. The system of claim 14 , further comprising:

a Trusted Platform Module (TPM) in which the common key K is filed.

16. The system of claim 14 , wherein the calculating unit determines at least one of A and C, wherein A:=AUTH[K auth R , N, M, |M|], where K auth R is a result of a secure authentication calculation using the common key K, and C:=ENC[K enc R , Z, N, M] where K enc R is a result of a secure encryption calculation using the common key K.

17. The system of claim 11 , wherein the first computing unit determines whether the message counter N is less than a maximum message counter N max , and upon determining whether N is less than N max , the first computing unit sets N:=N+1.

18. The system of claim 11 , wherein the self-service automat is an automated teller machine (ATM).

19. The system of claim 11 , wherein the bus system is a universal serial bus (USB) with wired or wireless operation.

Assignments (10)