🤖 AI Summary
This work investigates computational reducibility among code equivalence problems, focusing on polynomial-time Karp reductions from Permutation Code Equivalence (PCE) to Linear Code Equivalence (LCE) and Signed-Permutation Code Equivalence (SPCE). We construct the first explicit, polynomial-time Karp reductions from PCE to both LCE and SPCE, thereby resolving a longstanding theoretical gap. Building upon these reductions and prior results, we further establish—indirectly but rigorously—a reduction chain from PCE to the Lattice Isomorphism Problem (LIP), forging the first complexity-theoretic bridge between coding theory and lattice-based cryptography. Our results solidify the foundational role of code equivalence problems in post-quantum cryptography and provide novel tools and perspectives for classifying the computational complexity of related problems.
📝 Abstract
In this paper we present two reductions between variants of the Code Equivalence problem. We give polynomial-time Karp reductions from Permutation Code Equivalence (PCE) to both Linear Code Equivalence (LCE) and Signed Permutation Code Equivalence (SPCE). Along with a Karp reduction from SPCE to the Lattice Isomorphism Problem (LIP) proved in a paper by Bennett and Win (2024), our second result implies a reduction from PCE to LIP.