Abdul Alif ZakariaA. H. AzniFarida RidzuanNur Hafiza ZakariaMaslina Daud2024-05-282024-05-2820202022-1-281985-5753863-29https://mscr.org.my/data/journal/journal-20210427151256.pdfhttps://oarep.usim.edu.my/handle/123456789/4276Volume 10 Issue (2) (July - December 2020)RECTANGLE lightweight algorithm is a 64-bit block cipher using 80-bit and 128-bit key variants. A lightweight algorithm takes lesser computational power than a conventional algorithm. Implementing a lightweight algorithm in low-resource devices is more effective. To ensure the output has no pattern, randomness is an essential property for an algorithm. The NIST Statistical Test Suite is used to execute the randomness analysis. To produce 1,000 input sequences for each algorithm, nine data categories are implemented. RECTANGLE-80 and RECTANGLE-128 passed the randomness analysis with 98.73% and 98.48%. The results reveal that RECTANGLE appears to be non-random based on the 0.1% significance level. The analysis findings found weaknesses that can be explored in future research.en-USRandomness, NIST statistical test suite, RECTANGLE, data category, lightweight block cipherArticle122102