Author ORCID Identifier
https://orcid.org/0000-0002-9234-5529
Biosketch
Dr. Arulmani K. is an academician with over 25 years of academic experience, currently serving as an Assistant Professor in the Department of Computer Science and Engineering at SASTRA Deemed to be University. He was awarded a Ph.D. in Information Security from SASTRA Deemed to be University, where his research focused on advanced cryptographic system design. He specializes in cryptographic algorithm design, secure systems engineering, and performance optimization, and is best known for the Two-Key Dependent Permutation (TKDP) framework and its applications in secure file encryption, stream ciphers, and block cipher design. His research interests include post-quantum cryptography, randomness testing, steganography, and image/audio protection. By integrating classical and modern security techniques, he develops resilient systems applicable to both academic research and real-world deployment. He combines mathematical rigor with practical implementation, validating his work through NIST randomness testing, avalanche effect studies, and entropy-driven security analysis.
Date of Award
27-2-2025
Document Type
Thesis
School
School of Computing
Programme
Ph.D.-Doctoral of Philosophy
First Advisor
Dr. V. Ramaswamy
Keywords
Two Key Dependent Permutation, TKDP Based Symmetric Block Cipher, Key Dependent Dynamic S Box and P Box, Key Pair Generation and Encryption Decryption Mechanism, Algorithm, Permutation Sequence, Feistel Network Structure, Permutation, Encryption Decryption Mechanism, Cryptography, Applications, Information, Data Security
Abstract
Two-Key Dependent Permutation (TKDP) algorithm for generating permutation sequences of fixed sizes, TKDP based Symmetric Block Cipher (TKDPSBC) and TKDP Audio encryption are being proposed in this thesis. TKDP algorithm is capable of generating different sequences for different key pairs. This makes it suitable for constructing dynamic S-boxes and P-boxes that have more degree of randomness and non-linearity to resist cryptanalytic attacks. Rigorous statistical tests validate the efficacy of the generated permutation sequences, affirming their suitability for cryptographic applications in conjunction with Fiestel network-based block ciphers. TKDPSBC encrypts a plaintext block into a ciphertext block of the same size. TKDP algorithm plays pivotal role in TKDPSBC and is instrumental in constructing dynamic, scalable and nonlinear S-boxes and P-boxes to enhance confusion and diffusion, effectively withstanding various forms of cryptanalytic attacks. This innovative cipher design boasts several noteworthy features which include reduction of weak keys, generation of distinct ciphertext blocks for repeated plaintext blocks, and support for processing plaintexts of variable key sizes. TKDP tables are integrated at various stages of encryption which improves security further. Tests conducted on plaintext blocks of various sizes ranging from 128 to 320 bits using keys of same sizes demonstrate that approximately half the bits in the ciphertext on an average undergo alteration. Extensive tests carried out to identify weak keys within the 216 key space reveal that TKDPSBC utilizes an increased number of usable keys compared to DES space. TKDPSBC along with other symmetric algorithms such as DES, 3DES, Blowfish and AES has undergone comprehensive testing to assess encryption time and speed. It is observed that TKDPSBC exhibits superior performance in terms of both encryption time and speed next to AES. For enhanced security, TKDPSBC can be deployed with key lengths ranging from a minimum of 128 bits to a maximum of 640 bits effectively mitigating cryptanalysis attacks. As an application of TKDP algorithm, TKDP Audio Encryption for encrypting short length uncompressed audio/speech signal has been proposed. The results show that audio encryption scrambles original speech signal by adding more chaos with the help of permutation sequences generated using TKDP algorithm. This produces an encrypted signal with high degree of speech unintelligibility making it secure against various attacks.
Recommended Citation
K, Arulmani Mr., "Two-Key Dependent Permutation (TKDP) and its Applications in Information Security" (2025). Theses and Dissertations. 2.
https://knowledgeconnect.sastra.edu/theses/2
Graphical Abstract