Apparatus and method for transmitting and receiving data

1. An apparatus for transmitting data, the apparatus comprising:

an authentication code generator configured to generate a message authentication code using an i-th message and an encryption key assigned to the i-th message, wherein i denotes an integer;

an encryption unit configured to generate a first cryptogram by encrypting the message authentication code using first encryption keys from an encryption key assigned to an (i−1)-th message to another encryption key assigned to an (i−d+1)-th message, and generate a second cryptogram by encrypting the message authentication code using second encryption keys from the encryption key assigned to the (i−1)-th message to a different encryption key assigned to an (i-d)-th message, wherein d denotes an integer greater than or equal to 1; and

a transmitter configured to transmit the i-th message, the first cryptogram, and the second cryptogram, which are used to determine whether the i-th message is valid.

2. The apparatus of claim 1 , wherein the encryption unit is further configured to generate the first cryptogram by sequentially encrypting the message authentication code using the first encryption keys ranging from the encryption key assigned to the (i−1)-th message to the other encryption key assigned to the (i−d+1)-th message; and generate the second cryptogram by sequentially encrypting the message authentication code using the second encryption keys ranging from the encryption key assigned to the (i−1)-th message to the different encryption key assigned to the (i-d)-th message.

3. The apparatus of claim 2 , wherein the transmitter is further configured to transmit the different encryption key assigned to the (i-d)-th message with the i-th message, the first cryptogram, and the second cryptogram.

4. An apparatus for receiving data, the apparatus comprising:

a receiver configured to receive a first data packet comprising an i-th message, a first cryptogram associated with the i-th message, and a second cryptogram associated with the i-th message, and a second data packet comprising an encryption key assigned to an (i-k)-th message, wherein

i denotes an integer,

k denotes an integer greater than or equal to zero,

the first cryptogram is generated by encrypting a message authentication code using first encryption keys from an encryption key assigned to an (i−1)-th message to another encryption key assigned to an (i−d+1)-th message, and

the second cryptogram is generated by encrypting the message authentication code using second encryption keys from the encryption key assigned to the (i−1)-th message to a different encryption key assigned to an (i-d)-th message, wherein d denotes an integer greater than or equal to 1;

a storage unit configured to store the i-th message, the first cryptogram, and the second cryptogram; and

a control unit configured to manage a storage status of the i-th message, the first cryptogram, and the second cryptogram using the encryption key assigned to the (i-k)-th message, the i-th message, the first cryptogram, and the second cryptogram.

5. The apparatus of claim 4 , wherein the first cryptogram is generated by generating a message authentication code using the i-th message and an encryption key assigned to the i-th message, and sequentially encrypting the message authentication code and

the second cryptogram is generated by sequentially encrypting the message authentication code.

6. The apparatus of claim 5 , wherein the control unit is further configured to restore an encryption key assigned to an (i-k−1)-th message from the encryption key assigned to the (i-k)-th message, generate a second decryptogram by decrypting the second cryptogram using the restored encryption key assigned to the (i-k−1)-th message, and manage the storage status of the i-th message, the first cryptogram, and the second cryptogram based on a comparison between the first cryptogram and the second decryptogram.

7. The apparatus of claim 6 , wherein the control unit is further configured to, in response to the second decryptogram being identical to the first cryptogram, generate a first decryptogram by decrypting the first cryptogram using the encryption key assigned to the (i-k)-th message, substitute the first cryptogram with the first decryptogram by storing the first decryptogram in the storage unit in place of the first cryptogram, and substitute the second cryptogram with the second decryptogram by storing the second decryptogram in the storage unit in place of the second cryptogram.

8. The apparatus of claim 6 , wherein the control unit is further configured to, in response to the second decryptogram being different from the first cryptogram, delete, from the storage unit, the i-th message, the first cryptogram, and the second cryptogram.

9. The apparatus of claim 4 , wherein the control unit is further configured to generate a message authentication code associated with the i-th message using the i-th message and the encryption key assigned to the (i-k)-th message, and manage the storage status of the i-th message, the first cryptogram, and the second cryptogram based on a comparison between the message authentication code and the first cryptogram.

10. The apparatus of claim 9 , wherein the control unit is further configured to, in response to the message authentication code being different from the first cryptogram, delete, from the storage unit, the i-th message, the first cryptogram, and the second cryptogram.

11. A method of transmitting data, the method comprising:

generating, using a processor, a message authentication code using an i-th message and an encryption key assigned to the i-th message, wherein i denotes an integer;

generating, using the processor, a first cryptogram by encrypting the message authentication code using first encryption keys from an encryption key assigned to an (i−1)-th message to another encryption key assigned to an (i−d+1)-th message, and generating a second cryptogram by encrypting the message authentication code using second encryption keys from the encryption key assigned to the (i−1)-th message to a different encryption key assigned to an (i-d)-th message, wherein d denotes an integer greater than or equal to 1; and

transmitting, using the processor, the i-th message, the first cryptogram, and the second cryptogram, which are used to determine whether the i-th message is valid.

12. The method of claim 11 , wherein the generating of the first cryptogram and the second cryptogram comprises:

generating the first cryptogram by sequentially encrypting the message authentication code using the first encryption keys ranging from the encryption key assigned to the (i−1)-th message to the other encryption key assigned to the (i−d+1)-th message; and

generating the second cryptogram by sequentially encrypting the message authentication code using the second encryption keys ranging from the encryption key assigned to the (i−1)-th message to the different encryption key assigned to the (i-d)-th message.

13. The method of claim 12 , wherein the transmitting further comprises transmitting the different encryption key assigned to the (i-d)-th message together with the i-th message, the first cryptogram, and the second cryptogram.

14. A method of receiving data, the method comprising:

receiving, using a processor, a first data packet comprising an i-th message, a first cryptogram associated with the i-th message, and a second cryptogram associated with the i-th message, wherein

i denotes an integer,

the first cryptogram is generated by encrypting the message authentication code using first encryption keys from an encryption key assigned to an (i−1)-th message to another encryption key assigned to an (i−d+1)-th message, and

the second cryptogram is generated by encrypting the message authentication code using second encryption keys from the encryption keys assigned to the (i−1)-th message to a different encryption key assigned to an (i-d)-th message, wherein d denotes an integer greater than or equal to 1;

storing, using the processor, the i-th message, the first cryptogram, and the second cryptogram;

receiving, using the processor, a second data packet comprising an encryption key assigned to an (i-k)-th message, wherein k denotes an integer greater than or equal to zero; and

managing, using the processor, a storage status of the i-th message, the first cryptogram, and the second cryptogram using the encryption key assigned to the (i-k)-th message, the i-th message, the first cryptogram, and the second cryptogram.

15. The method of claim 14 , wherein the first cryptogram is generated by generating a message authentication code using the i-th message and an encryption key assigned to the i-th message, and generating the first cryptogram by sequentially encrypting the message authentication code; and

the second cryptogram is generated by sequentially encrypting the message authentication code.

16. The method of claim 15 , wherein the managing comprises:

restoring an encryption key assigned to an (i-k−1)-th message from the encryption key assigned to the (i-k)-th message;

generating a second decryptogram by decrypting the second cryptogram using the restored encryption key assigned to the (i-k−1)-th message; and

managing the storage status of the i-th message, the first cryptogram, and the second cryptogram based on a comparison between the first cryptogram and the second decryptogram.

17. The method of claim 16 , wherein the managing further comprises, in response to the second decryptogram being identical to the first cryptogram:

generating a first decryptogram by decrypting the first cryptogram using the encryption key assigned to the (i-k)-th message;

substituting the first cryptogram with the first decryptogram by storing the first decryptogram in place of the first cryptogram; and

substituting the second cryptogram with the second decryptogram by storing the second decryptogram in place of the second cryptogram.

18. The method of claim 16 , wherein the managing comprises, in response to the second decryptogram being different from the first cryptogram, deleting the stored i-th message, the stored first cryptogram, and the stored second cryptogram.

19. The method of claim 14 , wherein the managing comprises:

generating a message authentication code associated with the i-th message using the i-th message and the encryption key assigned to the (i-k)-th message; and

managing the storage status of the i-th message, the first cryptogram, and the second cryptogram based on a comparison between the message authentication code and the first cryptogram.

20. A system for transmitting and receiving data, the system comprising:

an authentication code generator configured to generate a message authentication code using an i-th message and an encryption key assigned to the i-th message, wherein i denotes an integer;

an encryption unit configured to generate a first cryptogram by encrypting the message authentication code using first encryption keys from an encryption key assigned to an (i−1)-th message to another encryption key assigned to an (i−d+1)-th message, and generate a second cryptogram by encrypting the message authentication code using second encryption keys from the encryption key assigned to the (i−1)-th message to a different encryption key assigned to an (i-d)-th message, wherein d denotes an integer greater than or equal to 1;

a transmitter configured to transmit a first data packet comprising the i-th message, the first cryptogram, and the second cryptogram, and a second data packet comprising the different encryption key assigned to the (i-d)-th message, which are used to determine whether the i-th message is valid;

a receiver configured to receive the first data packet comprising the i-th message, the first cryptogram, the second cryptogram, and the second data packet comprising the different encryption key assigned to the (i-d)-th message;

a storage unit configured to store the i-th message, the first cryptogram, and the second cryptogram; and

a control unit configured to manage a storage status of the i-th message, the first cryptogram, and the second using the different encryption key assigned to the (i-d)-th message, the i-th message, the first cryptogram, and the second cryptogram.