An Enhanced Key Schedule Algorithm of PRESENT-128 Block Cipher for Random and Non-Random Secret Keys

The key schedule algorithm (KSA) is a crucial element of symmetric block ciphers with a direct security impact. Despite its undeniable significance, the KSA is still a less focused area in the design of an encryption algorithm. PRESENT is a symmetric lightweight block cipher that provides the optima...

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Bibliographic Details
Main Authors: Maria Imdad, Sofia Najwa Ramli, Hairulnizam Mahdin
Format: Article
Language:English
Published: MDPI AG 2022-03-01
Series:Symmetry
Subjects:
Online Access:https://www.mdpi.com/2073-8994/14/3/604
Description
Summary:The key schedule algorithm (KSA) is a crucial element of symmetric block ciphers with a direct security impact. Despite its undeniable significance, the KSA is still a less focused area in the design of an encryption algorithm. PRESENT is a symmetric lightweight block cipher that provides the optimal balance between security, performance, and minimal cost in IoT. However, the linear functions in KSA lead to a slow and predictable bit transition, indicating the relationship between round keys. A robust KSA should produce random and independent round keys irrespective of the secret key. Therefore, this research aims to improve the KSA PRESENT-128 block cipher with enhanced randomness, round key bit difference, and the avalanche effect. The experiments on round keys and ciphertext with random, low density and high-density secret key datasets endorse the expected improvements. Moreover, the results show that the improved KSA produces random round keys that successfully pass the NIST randomness test. The bit transition from one round key to another is increased from 20% to 40%, where a greater inclination of the avalanche effect has an increased effect with 50% bit change. On the other hand, the improved KSA PRESENT requires an additional <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.001871</mn></mrow></semantics></math></inline-formula> s to generate round keys, as a security cost trade-off.
ISSN:2073-8994