Professor Tsuyoshi Takagi’s research group and KDDI Research, Inc.(President and CEO:Satoshi Konishi) jointly succeeded in decrypting 210-dimensional, 220-dimensional, 230-dimensional, and 240-dimensional code-based cryptgraphic ciphers based on a set of three elements:[0],[1], and [2]. This achievement was made in the “Challenges for code-based problems” decryption contest for post-quantum cryptography(PQC), which is being standardized in the United States as next-generation cryptography. Furthermore, on December 15, 2025, they confirmed that the ternary-based code-based cryptosystem resulting from this achievement achieves equivalent security to the US standard PQC code-based cryptsystem with less than one-tenth the dimension(data size). This breakthrough involved developing and implementing an effective algorithm for cryptographic codes over ternary fields using partitioning and parallel processing, successfully decrypting codes previously unsolvable. This demonstrates the validity of a theoretical framework for thoroughly evaluating the security of cryptographic systems based on binary or ternary fields, paving the way for new cryptographic schemes utilizing novel mathematical structures. The joint research group of Professor Takagi’s group and KDDI Research plans to present these findings at the “Symposium on Cryptography and Information Security 2026(SCIS2026)” held in Hakodate City for five days starting January 26.
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