Permutation Polynomials in RSA-Cryptosystems

Abstract

For the transmission of information in public-key cryptosystems a receiver R makes an enciphering key E_R public and keeps a deciphering key D_R secret. A sender S can read R’s public key E_R and enciphers a message M as E_R(M). Only the authorised receiver R knows the correct key D_R to reproduce the massage M by forming D_R(E_R(M)) = M. Here the key E_R has to be computationally easy to handle, but it has to be computationally infeasible to derive D_R from the knowledge of E_R above. If sender S wants to “sign” the message, she sends E_R(D_S (M)) and the receiver deciphers it as E_S(D_R(E_R(D_S (M)))) = M. Here E_S and D_S are the enciphering and deciphering keys, respectively, of S.