Method for synchronizing a receiver initialization vector with a transmitter initialization vector

Patent metadata

Field	Value
Publication number	US-11956358-B2
Application number	US-202117330733-A
Country	US
Kind code	B2
Filing date	May 26, 2021
Priority date	May 26, 2020
Publication date	Apr 9, 2024
Grant date	Apr 9, 2024

Abstract

A method for synchronizing transmitter and receiver initialization vectors includes: generating a key and providing the key to a transmitter and a receiver; initializing a transmitter initialization vector and a receiver initialization vector with an initialization vector; forming a transmitter partial counter from a counter of the transmitter initialization vector; encrypting a message using the key and the transmitter initialization vector; generating and transmitting a data packet containing the encrypted message and the transmitter partial counter; incrementing the counter; receiving a data packet with an encrypted message and the transmitter partial counter; extracting the transmitter partial counter from the data packet; forming a receiver partial counter from a counter of the receiver initialization vector; based on a comparison of the receiver partial counter and the transmitter partial counter, changing the counter of the receiver initialization vector; decrypting the message and incrementing the counter of the receiver initialization vector.

First claim

The invention claimed is:

1. A method for synchronizing a receiver initialization vector of a receiver with a transmitter initialization vector of a transmitter during continuous transmission of encrypted data packets from the transmitter to the receiver, comprising:
generating a key;
generating an initialization vector with a counter with N bits;
providing the key to the transmitter and the receiver;
initializing the transmitter initialization vector and the receiver initialization vector with the initialization vector;
forming a transmitter partial counter with the lowest value M bits less than N bits from the counter of the transmitter initialization vector;
encrypting a message according to an encryption method using the key and the transmitter initialization vector to ensure confidentiality;
generating and transmitting a data packet containing the encrypted message and the transmitter partial counter;
thereafter incrementing the counter of the transmitter initialization vector;
after the step of generating and transmitting the data packet, receiving the data packet at the receiver;
after the step of receiving the data packet, extracting the transmitter partial counter from the data packet;
forming a receiver partial counter with the lowest value M bits less than N bits from the counter of the receiver initialization vector;
after the steps of extracting the transmitter partial counter and forming the receiver partial counter, performing a comparison between the receiver partial counter and the transmitter partial counter;
when the comparison results in a higher transmitter partial counter than receiver partial counter, replacing the lowest value M bits of the counter of the receiver initialization vector by the transmitter partial counter;
when the comparison results in a lower transmitter partial counter than receiver partial counter, replacing the lowest value M bits of the counter of the receiver initialization vector by the transmitter partial counter, and increasing the value of the counter of the receiver initialization vector by 2 M ; and
thereafter decrypting the message according to the encryption method using the key and the receiver initialization vector, and then incrementing the counter of the receiver initialization vector,
wherein M is an integer that is greater than 0, and wherein N is an integer that is greater than 1.

2. The method according to claim 1 , further comprising:
checking, by the receiver, whether the decryption is successful; and
when the decryption is not successful, increasing the value of the counter of the receiver initialization vector by another 2 M , and decrypting the message again according to the encryption method using the key and the receiver initialization vector.

3. The method according to claim 1 , wherein the key and the initialization vector are generated by an initializer and provided to the transmitter and the receiver.

4. The method according to claim 1 , wherein the encryption method implements an Advanced Encryption Standard.

5. The method according to claim 1 , further comprising:
generating a message authentication code for the message by the transmitter to ensure authenticity and/or integrity of the message;
wherein the step of generating and transmitting the data packet involves generating the data packet with the message authentication code; and
after the step of receiving the data packet at the receiver, checking authenticity and/or integrity of the message by the receiver by evaluating the message authentication code.

6. The method according to claim 5 , wherein a CCM or a GCM mode is implemented by the transmitter and the receiver for generating and checking the message authentication code.

7. The method according to claim 1 , further comprising:
generating a message authentication code for the message and the transmitter partial counter for ensuring authenticity and/or integrity of the message and of the transmitter partial counter;
wherein the step of generating and transmitting the data packet involves generating the data packet with the message authentication code; and
checking authenticity and/or integrity of the message and of the transmitter partial counter by the receiver by evaluating the message authentication code.

8. The method according to claim 1 , wherein the initialization vector is generated with a nonce in order to improve the assurance of confidentiality or authenticity and integrity.

9. The method according to claim 1 , wherein a radio technology is used to transmit data packets from the transmitter to the receiver.

10. The method according to claim 9 , wherein the radio technology is Bluetooth Low Energy.

Assignees

• Krohne Messtechnik Gmbh

Inventors

• Wesskamp Patrick

Classifications

• H04L9/12 Primary

  Transmitting and receiving encryption devices synchronised or initially set up in a particular manner · CPC title

• H04L9/0631 Primary

  Substitution permutation network [SPN], i.e. cipher composed of a number of stages or rounds each involving linear and nonlinear transformations, e.g. AES algorithms · CPC title

• H04L9/0819

  Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) (network architectures or network communication protocols for key distribution in a packet data network H04L63/062) · CPC title

• H04L9/3242

  involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC · CPC title

• H04L63/0435

  wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption (cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06) · CPC title