THE QUADRATIC AND DOUBLE QUADRATIC RESIDUE CIPHERS
Frank Rubin · Cryptologia · 1995
In a recent article in this journal Shepherd, Sanders and Stockel compare the quadratic residue cipher (QRC) to the Rivest-Shamir-Adleman (RSA) public key cipher. They discuss a number of advantages of the QRC over the RSA, but also indicate a number of shortcomings. In this paper I attempt to redress some of those supposed shortfalls. I introduce the double quadratic residue cipher, which is both faster and more secure than either the QRC or the RSA.