Device and process for processing a message and sending a LPWAN message
A process for processing a received message, where the message includes encrypted data and at least one indicator element, is disclosed. The process includes generating a complete indicator from data stored in the electronic device and from the received indicator element, generating a key from the complete indicator, and decrypting the encrypted data using said key. The disclosure also relates to a corresponding sending process.
1. A process for receiving a message executed by an electronic device, the message comprising encrypted data and at least one indicator element, the process comprising:
generating a complete indicator from data stored in the electronic device and from the received indicator element,
generating a key from at least the complete indicator,
decrypting said encrypted data using said key, wherein the complete indicator is a counter of sent and received messages which can be registered on M+N bits, M and N being non-zero integers,
the received indicator element being a number of N consecutive bits,
the stored data comprising at least one number of M consecutive bits,
the elaboration of the complete indicator comprising a binary concatenation of said number of M consecutive bits with said number of N consecutive bits, said number of N consecutive bits forming the low-weight bits of the complete indicator.
2. The process according to claim 1 , wherein said received indicator element is in an unencrypted portion of the message.
3. The process according to claim 1 , wherein said received indicator element is in an unencrypted header of the received message.
4. The process according to claim 1 , wherein if the decryption does not deliver the encrypted decrypted plaintext data, the process further comprises:
determining another indicator element value selected from a group of predetermined indicator element values is determined, and
using this selected value to generate the complete indicator.
5. The process according to claim 4 , wherein the group of predetermined indicator element values comprises the possible 2 N −1 values which can be written to N bits.
6. The process according to claim 1 , wherein the stored data comprise said number of M consecutive bits, indicating a value A, and a number of N consecutive bits, indicating a value B,
said number of N consecutive bits of the received indicator element indicating a value Y,
and in which if Y is strictly greater than B then the elaboration of the complete indicator comprises the binary concatenation of A and Y and the storing of the resulting complete indicator,
if not, the elaboration of the complete indicator comprises the concatenation of A+1 and of Y.
7. The process according to claim 6 , wherein the resulting complete indicator is stored as new stored data, the previous stored data being replaced by the resulting indicator.
8. The process according to claim 1 , comprising receiving said message via a low-power wireless link.
9. A process for sending a message executed by an electronic device, the process comprising:
determining a complete indicator,
generating a key from at least the complete indicator,
generating an indicator element from the complete indicator,
encrypting data using said key to obtain encrypted data, wherein the message to be sent comprises said indicator element and said encrypted data, and wherein the complete indicator is a counter of sent and received messages which can be registered on M+N bits, M and N being non-zero integers, the complete indicator comprising, in the form of binary concatenation, a number of M consecutive bits and a number of N consecutive bits, said number of N consecutive bits forming the low-weight bits of the complete indicator and said indicator element.
10. The process according to claim 9 , wherein said indicator element is placed in an unencrypted portion of the message to be sent.
11. The process according to claim 9 , wherein determining the complete indicator comprises updating a complete indicator stored in the electronic device.
12. The process according claim 9 , wherein the message is sent by a low-power wireless link.
13. An electronic device comprising:
a processor configured for
receiving a message comprising encrypted data and at least one indicator element,
generating a complete indicator from data stored in the electronic device and from the received indicator element,
generating a key from at least the complete indicator,
decrypting said encrypted data using said key, and
wherein the complete indicator is a counter of sent and received messages which can be registered on M+N bits, M and N being non-zero integers,
the received indicator element being a number of N consecutive bits,
the stored data comprising at least one number of M consecutive bits,
the elaboration of the complete indicator comprising a binary concatenation of said number of M consecutive bits with said number of N consecutive bits, said number of N consecutive bits forming the low-weight bits of the complete indicator.
14. The electronic device according to claim 13 , comprising a server or a mobile electronic device.
15. An electronic system comprising:
a processor configured for:
determining a complete indicator,
generating a key from at least the complete indicator,
generating an indicator element from the complete indicator,
encrypting data using said key to obtain encrypted data,
generating the message to be sent, the message to be sent comprising said indicator element and said encrypted data,
sending the message to be sent,
wherein the complete indicator is a counter of sent and received messages which can be registered on M+N bits, M and N being non-zero integers,
the complete indicator comprising, in the form of binary concatenation, a number of M consecutive bits and a number of N consecutive bits, said number of N consecutive bits forming the low-weight bits of the complete indicator and said indicator element.
16. The system according to claim 15 , comprising a server and/or a mobile electronic device.