In this research paper, we present and compare the randomness analysis conducted towards LBlock block cipher and its modified version namely Modified LBlock. Among the important requirement when designing a block cipher algorithm is that the algorithm can act as a random number generator. Therefore, the aim of performing modification towards LBlock algorithm is to enhance its randomness results. Modification were made by replacing the eight 4 X 4 S-boxes with four different 16 X 16 S-boxes which has the same security strength as S-box of AES. During experimentation, this research project considers a full rounds of LBlock and Modified LBlock algorithms which both algorithms accepts a 64-bit plaintext, utilizes an 80-bit key, executes in 32 rounds and produces a 64-bit ciphertext. Nine different data categories were used to generate inputs (plaintext and key), with each having 100 samples. Blocks of ciphertext were generated from these algorithms and were concatenated to construct a binary sequence. NIST Statistical Test Suite consisting of sixteen tests was used to conduct testing and analysis, and the significance level was set to 1%. From the comparative analysis done, it is concluded that the randomness analysis results for Modified LBlock block cipher has 42.96% improvement compared to its original design when tested under 1% significance level and using the same samples.

Cryptography has been extensively employed in the information security field for the purpose of providing security for confidential data. The field of cryptography has recently considered a hybrid cryptographic implementation that combines conventional cryptographic techniques with the knowledge of DNA technologies to formulate what is known as DNA cryptography. DNA based cryptography is considered a branch of sustainability science as it combines transdisciplinary structures from natural sciences (biology) and technological sciences (information security). This paper discusses the various biological DNA techniques that have been implemented in recent DNA cryptographic algorithms. Among them are the Watson-Crick Complementary Rules, DNA Encoding/Decoding Rules, DNA Operation Rules, the Triplet Codon DNA Code, DNA Segmentation, DNA Hybridisation (DNA Annealing) and DNA Transcription and DNA Replication from the Central Dogma Molecular Biology process. A description of the algorithms and a theoretical comparative analysis of these DNA cryptographic algorithms is also presented in this research paper. Comparisons have also been made based on the following parameters: Conventional cryptographic techniques vis-a-vis the techniques used by DNA cryptographic algorithms, the application of these algorithms, their limitations and a security analysis to see how well DNA cryptography perform as against current conventional cryptography.