Message Authentication Code Tag Value Selection via Error Correcting Codes
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Solution Overview
Problem
Existing message authentication code (MAC) systems face challenges in providing high forgery protection with small tag sizes and key sizes, especially in wireless communications where data integrity and authenticity are critical, and manual authentication schemes require short tag values for efficient comparison and transfer.
Innovation Solution
A method that determines a tag value by selecting a symbol from an error correcting code codeword based on a key, allowing for high forgery security even with small tag and key sizes, and optionally using a hash value of the message to further reduce size while maintaining security, utilizing error correcting codes to ensure unconditional security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MAC algorithms (e.g., HMAC, MD5) are used to provide data integrity protection, then security and authentication are improved, but the tag value length becomes large making manual comparison and transfer impractical
Solution Approach 1:
The patent extracts only the essential authentication information from the full MAC calculation. Instead of using the complete hash value (e.g., 160 bits for SHA-1), the system computes a condensed authentication value that contains only the necessary bits for verification, reducing the tag length to a manageable size for manual operations while maintaining security
Solution Approach 2:
The patent changes the parameter of tag value length by using selective bit extraction and truncation. The system calculates the full MAC but then extracts only specific bits or a reduced portion of the hash value, transforming the tag from a long cryptographic value to a short authentication code that is suitable for manual comparison while preserving the security properties
2Ease of operation
If the tag value length is reduced for manual authentication schemes, then ease of operation is improved, but the security level and forgery protection may be compromised
Solution Approach 1:
The patent segments the authentication process into two parts: a comprehensive MAC calculation that ensures security, and a selective extraction that provides the short tag for manual verification. The system divides the hash value into segments or extracts specific bit patterns, allowing the short tag to represent the authentication result without losing security
Solution Approach 2:
The patent introduces an intermediary approach where the full MAC calculation serves as a mediator between the security requirement and the usability requirement. The system computes the complete authentication value internally but presents only a condensed version to the user, using the full MAC as a mediator that ensures both security and ease of manual verification
3Device complexity
If small key sizes are used to reduce complexity, then device complexity is reduced, but security against forgery attacks may be weakened
Solution Approach 1:
The patent applies partial action by using only the necessary portion of the key space. Instead of requiring full-length cryptographic keys (e.g., 128 or 256 bits), the system uses a reduced key size that is still sufficient for security when combined with the selective bit extraction method. This partial key usage reduces complexity while maintaining adequate security through the complementary authentication mechanism
Data Source
AI summary
A method of processing a message to determine a tag value from the message and from a key according to a message authentication code. The method including the steps of selecting one of a plurality of symbols, the plurality of symbols forming a codeword encoding a data item derived from the message, the codeword encoding the data item according to an error correcting code, wherein said key determines which one of said plurality of symbols is selected; and determining the tag value to be the selected symbol.