AES Decryption Speed via InvMixColumn Precomputation
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Solution Overview
Problem
The Advanced Encryption Standard (AES) decryption process, particularly the MixColumns and InvMixColumns operations, is processing-intensive, leading to significant computational time, which hinders efficient data decryption.
Innovation Solution
Precomputing the product of each element value of the InvMixColumn matrix with each possible value of the input state array and using these precomputed products to perform the InvMixColumn operation, reducing the need for real-time calculations and enhancing processing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the InvMixColumn operation is performed using standard real-time calculations, then the decryption process maintains correctness, but the processing time increases significantly
Solution Approach 1:
The patent precomputes the products of each element value of the InvMixColumn matrix with each possible value of the input state array before the actual decryption operation. This preliminary computation creates lookup tables that store precalculated results, allowing the decryption process to simply retrieve and use these precomputed values during execution, thereby eliminating the need for time-consuming real-time calculations and significantly reducing decryption time.
2Speed
If precomputation is performed for the InvMixColumn operation, then the decryption speed improves, but the memory requirements increase
Solution Approach 1:
The patent precomputes and stores the products of matrix elements with possible input values in memory before decryption. This creates lookup tables that can be quickly accessed during the decryption process, trading the one-time memory cost of precomputation for significantly reduced operational time during actual decryption operations.
Data Source
AI summary
A method is provided for decrypting data encrypted according to a cipher key according the advanced encryption standard (AES). The method includes precomputing a product of each element value of an InvMixColumn matrix and each possible value of an input state array and deriving a set of round keys from the cipher key and the set of round keys. The deriving includes providing an initial round key and a plurality of further round keys, performing an initial decryption round, and performing N full decryption rounds at least in part using the precomputed product of each element value of an InvMixColumn matrix and each possible value of the input state array.