Proposal of a New Block Cipher reasonably Non-Vulnerable against Cryptanalytic Attacks

This paper proposes a new block cipher termed as “Modular Arithmetic based Block Cipher with Varying Key-Spaces (MABCVK)” that uses private key-spaces of varying lengths to encrypt data files. There is a simple but intelligent use of theory of modular arithmetic in the scheme of the cipher. Based on observed implementation of the proposed cipher on a set of real data files of several types, all results are tabulated and analyzed.The schematic strength of the cipher and the freedom of using a long key-space expectedly can make it reasonably nonvulnerable against possible cryptanalytic attacks. As a part of the future scope of the work, it is also intended to formulate and implement an enhanced scheme that will use a carrier image to have a secure transmission of the private key.

💡 Research Summary

The paper introduces a new block cipher called the Modular Arithmetic based Block Cipher with Varying Key‑Spaces (MABCVK). Its core idea is to use modular multiplication and addition operations together with a key that can be extended to arbitrary lengths (e.g., 128, 192, 256 bits). Each encryption round applies a different pair of modulus parameters (K₁ for multiplication, K₂ for addition), and the round keys are swapped in a simple cyclic fashion. The authors claim that this “varying key‑space” approach makes the cipher reasonably resistant to brute‑force attacks while keeping computational overhead low.

To validate the design, the authors implemented MABCVK and tested it on several real‑world data files: plain text, BMP images, and WAV audio files ranging from 1 MB to 5 MB. They measured encryption and decryption times, presenting the results in tables that show a roughly linear increase in processing time with file size. They also report that increasing the key length from 128 to 256 bits does not noticeably affect runtime or ciphertext size, suggesting that the flexible key length does not degrade performance.

The security discussion is limited to the observation that a larger key space expands the search space for exhaustive key‑search attacks. No formal proofs, security reductions, or resistance analyses against differential, linear, or related‑key attacks are provided. The cipher’s structure—relying solely on modular arithmetic without additional diffusion or substitution layers—raises concerns about potential linear relationships that could be exploited by modern cryptanalytic techniques.

In the “future work” section, the authors propose embedding the secret key within a carrier image using steganographic techniques, aiming to protect key transmission against man‑in‑the‑middle attacks. While conceptually interesting, the paper does not detail how integrity, authenticity, or synchronization would be ensured, nor does it evaluate the impact of the carrier on overall security.

Overall, the manuscript presents an inventive but preliminary design. It offers a straightforward implementation and demonstrates modest performance on typical file types, yet it lacks rigorous security analysis, comparative benchmarks against established ciphers (e.g., AES), and a clear threat model. Consequently, while MABCVK may serve as an educational prototype, further cryptanalytic study and optimization would be required before it could be considered for practical deployment.