Sending and receiving messages
AssigneeNagravision Sarl
InventorBrecht Wyseur
Life of this patent
Estimating the term…
Abstract
The present disclosure relates to the exchange of information between a message sending device and a message receiving device with message authentication and proposes to reduce the time required for message authentication by pre-computing a message tag, such as a MAC, and subsequently replacing the computation of the MAC when the tag is to be validated (or indeed also on sending) by a table look-up. The approach requires a set of messages and works particularly well for small sets of messages, for example as small as two or three messages, or less than five or ten messages. The approach finds particular application in control networks where control decisions have to be taken quickly and securely, for example in the control of a vehicle, for example an autonomous vehicle, or the control of a smart electricity grid.
Claims17
A message-receiving device, the message-receiving device comprising:
- a memory configured to store a plurality of messages and corresponding message tags;
- a communications interface configured to receive a message-tag pair, the message-tag pair comprising a message tag and a corresponding message, from a message-sending device;
- and
- a processor configured to:
- combine each message of the plurality of messages with an authentication key to compute, for each message of the plurality of messages, a respective message tag of a plurality of message tags for validating one or more messages tags associated with one or more messages;
- store the plurality of message tags in the memory;
- validate the received message tag based on comparing the received message tag with the stored plurality of message tags to identify a matching message tag;
- in response to a trigger event, update the authentication key for computing one or more updated message tags;
- combine each message of the plurality of messages with the updated authentication key to compute a plurality of updated message tags;
- and
- store the plurality of updated message tags in the memory.
A message-sending device comprising:
- a memory configured to store a plurality of pairs of respective messages and corresponding message tags;
- a communications interface configured to transmit message tags;
- and
- a processor configured to:
- combine each message of the plurality of messages with an authentication key to generate, for each message of the plurality of messages, a respective message tag of a plurality of message tags for validating one or more message tags associated with one or more messages;
- store the plurality of message tags in the memory in association with a respective message of the plurality of messages as a respective message-tag pair,
- select a message to communicate to a message-receiving device;
- retrieve a message tag from a stored message-tag pair corresponding to the selected message from the memory;
- cause the communications interface to transmit the retrieved message tag corresponding to the selected message together with the selected message;
- in response to a trigger event, update the authentication key for computing one or more updated message tags;
- combine each message of the plurality of messages with the updated authentication key to compute a plurality of updated message tags;
- and
- store each updated message tag of the plurality of updated message tags in the memory in association with a respective message of the plurality of messages.
A method of receiving a message, the method comprising:
- combining each message of a plurality of messages with an authentication key to compute, for each message of the plurality of messages, a respective message tag of a plurality of message tags for validating one or more message tags associated with one or more messages;
- storing the plurality of messages and the plurality of message tags in a memory;
- receiving a message-tag pair, the message-tag pair comprising a message tag and a corresponding message, from a message-sending device;
- validating the received message tag based on comparing the received message tag with the stored plurality of message tags to identify a matching message tag;
- in response to a trigger event, updating the authentication key for computing one or more updated message tags;
- combining each of the plurality of messages with the updated authentication key to compute a plurality of updates message tags;
- and
- storing the plurality of updated message tags in the memory.
Dependencies are inferred from the claim text.