Iranian Society of Cryptology The ISC International Journal of Information Security 2008-2045 4 1 2012 01 01 Improving the Rao-Nam secret key cryptosystem using regular EDF-QC-LDPC codes 3 14 39193 10.22042/isecure.2015.4.1.2 EN R. Hooshmand T. Eghlidos M. R. Aref Journal Article 2011 12 03 This paper proposes an efficient joint secret key encryption-channel coding cryptosystem, based on regular Extended Difference Family Quasi-Cyclic Low-Density Parity-Check codes. The key length of the proposed cryptosystem decreases up to 85 percent using a new efficient compression algorithm. Cryptanalytic methods show that the improved cryptosystem has a significant security advantage over Rao-Nam cryptosystem against chosen plaintext attacks, benefiting from an improvement on the structure of the Rao-Nam cryptosystem and proper choices of code parameters. Moreover, the proposed cryptosystem benefits from the highest code rate and a proper error performance. https://www.isecure-journal.com/article_39193_98a64c8df299f3ea153b18fa25977625.pdf