Precomputed MAC Tables for Time-Critical Message Authentication
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Solution Overview
Problem
Existing message authentication methods in digital operations over communications networks require additional computational time for authentication and verification, which can compromise timeliness and safety in applications like autonomous driving and smart grids.
Innovation Solution
Pre-computing message authentication codes (MACs) and storing them in a table for fast look-up validation, combined with periodic key updates to reduce computational intensity and vulnerability to attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If message authentication is performed using traditional computational methods (digital signatures or MAC computation), then security and reliability are improved, but authentication time increases and timeliness deteriorates
Solution Approach 1:
The patent pre-computes message authentication codes (MACs) for all possible messages in the message space and stores them in a lookup table before actual communication occurs. When a message needs authentication, the receiver simply performs a table lookup comparing the received message's MAC against the pre-computed table, eliminating the need for real-time cryptographic computation and reducing authentication time from seconds to microseconds.
Solution Approach 2:
The patent creates a copy of the authentication verification process by pre-generating all possible authenticated message-MAC pairs and storing them in a database. Instead of performing cryptographic verification on the fly, the system copies the verification result into a searchable database, allowing instant authentication through comparison rather than computation.
2Productivity
If pre-computing all message authentication codes is done without key updates, then authentication speed is improved, but vulnerability to cryptographic attacks increases
Solution Approach 1:
The patent implements periodic updates of the authentication key at predetermined intervals. When the key is updated, the entire message authentication code table is re-computed using the new key. This periodic refresh prevents attackers from exploiting static pre-computed tables through pre-image or collision attacks, while maintaining the speed advantage of table lookup authentication during each key validity period.
Solution Approach 2:
The patent makes the authentication system dynamic by introducing key rotation. The message authentication code database is not static but is periodically regenerated with new keys. This dynamic approach balances the need for fast authentication (maintained through pre-computation) with security requirements (maintained through periodic key changes), preventing the system from being vulnerable to attacks against static cryptographic structures.
Data Source
AI summary
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.