Time of day encryption using TDMA timing
View Patent ↗Embodiments of the invention provide for encryption and decryption of data in a TDMA network using TDMA time values. In some embodiments, TDMA time values can be transmitted to terminals from a network controller using a burst time plan. These TDMA time values along with other data and/or counters can be combined to create a one-time key, which can be used to both encrypt data and/or decrypt data. Embodiments of the invention can decrease communication overhead by using the TDMA time value for TDMA purposes as well as for encryption purposes.
1. A method for encrypting data in a TDMA communication system at a transmitting terminal, the method comprising:
receiving a transmit TDMA timeslot assignment, with a TDMA time value, from a TDMA controller;
receiving data from a user;
calculating a one-time key-stream from at least the TDMA time value using a controller;
encrypting the data using the one-time key-stream to produce encrypted data with the controller; and
transmitting the encrypted data to a receiver.
2. The method according to claim 1 , wherein the TDMA communication system comprises a multi-frequency TDMA communication system.
3. The method according to claim 1 , wherein the one-time key-stream is calculated from a plurality of counter values.
4. The method according to claim 1 , wherein the calculating a one-time key-stream comprises:
creating a counter value from the TDMA time value; and
calculating a one-time key-stream from the counter value using a block encryption function.
5. The method according to claim 4 , wherein the counter value is created by combining the TDMA time value with one or more values selected from the group consisting of a transmission frequency representation, a system parameter, a block counter value, and a terminal parameter.
6. The method according to claim 1 , wherein a subsequent counter value is created by incrementing the previous counter value.
7. The method according to claim 1 , wherein the encrypting the data using the one-time key-stream further comprises creating the encrypted value using an exclusive disjunction function.
8. A method for decrypting data in a TDMA communication system at a TDMA controller, the method comprising:
receiving a receive TDMA timeslot assignment that includes a TDMA time value, from a TDMA controller;
receiving encrypted data from a transmitting terminal;
calculating a one-time key-stream from at least the TDMA time value using a controller;
decrypting, with the controller, the encrypted data using the one-time key-stream producing decrypted data; and
transmitting the decrypted data to a user.
9. The method according to claim 8 , wherein the one-time key-stream is calculated by encrypting the TDMA time value.
10. The method according to claim 8 , wherein the one-time key-stream is calculated by encrypting a plurality of counter values.
11. The method according to claim 8 , wherein the one-time key-stream is calculated using the TDMA time value and at least one value selected from the group consisting of a transmission frequency representation, a system parameter, and a terminal parameter.
12. The method according to claim 9 , wherein a subsequent counter value is created by incrementing a previous counter value.
13. The method according to claim 8 , wherein decrypting the data using the one-time key-stream further comprises creating the decrypted value using an exclusive disjunction function.
14. A method for decrypting data in a communication network, the method comprising:
transmitting a burst time plan to both the transmitting and the receiving terminals within a network of terminals, the burst time plan including at least a TDMA time value and specifying a timeslot within which the transmitting terminal should transmit data;
receiving encrypted data from the transmitting terminal within the timeslot specified by the burst time plan;
creating a counter value from at least the TDMA time value using a controller;
calculating a one-time key-stream from the counter value using the controller; and
decrypting, with the controller, the encrypted data using the one-time key-stream.
15. The method according to claim 14 , wherein consecutive counter values are incremented.
16. The method according to claim 14 , wherein the counter value is created using a value selected from the group consisting of a transmission frequency representation, a system parameter, and a terminal parameter.
17. The method according to claim 14 , wherein the one-time key stream is calculated from the counter value using a one-way function.
18. The method according to claim 14 , wherein the one-time key stream is calculated from the counter value using a block encryption function.
19. The method according to claim 14 , wherein the decrypting the encrypted data using the one-time key-value includes using an exclusive disjunction function.
20. A method for encrypting data in a communication network, the method comprising:
receiving a TDMA time value;
receiving data from a source distinct from the source of the TDMA time value;
calculating, with a controller, a one-time key-value from at least the TDMA time value;
encrypting the data, with the controller, using the one-time key-value; and
transmitting the encrypted data.
21. The method according to claim 20 , wherein the one-time key-value includes at least one value selected from the group of values consisting of a system identification value, a terminal identification value, and a carrier frequency value.
22. A communication modem comprising:
a user port configured to receive data from a user;
a network communications port;
a controller communicatively coupled with the user port and the network communications port; and
memory communicatively coupled with the controller, the memory including instructions executable by a processor, wherein the instructions include:
instructions to receive user data through the user port;
instructions to receive a burst time plan and store at least portions of the burst time plan in the memory, wherein the burst time plan includes a global time value;
instructions to calculate a one-time key-value from the global time value;
instructions to encrypt the user data with the one-time key-value; and
instructions to send the encrypted user data to a communications network using the network communications port.
23. The communication modem according to claim 22 , wherein the burst time plan includes an indication specifying a timeslot within which the communication modem should transmit the encrypted user data.
24. The communication modem according to claim 22 , wherein the instructions to calculate a one-time key-value from the global time value include instructions to calculate a one-time key-value from the global time value using a one-way function.