Signcryption Cryptosystem Scheme dengan Algoritma XRSA Public Key Encryption dan Nagaty Digital Signature

Abstract

Information security is a crucial issue in the digital era, especially in the transmission and storage of sensitive data. This research implements a signcryption scheme with a sign-then-encrypt approach to ensure confidentiality, authentication, integrity, and non-repudiation of messages. The scheme uses the XRSA algorithm for encryption and decryption processes, as well as Nagaty digital signatures for signature and verification. The XRSA algorithm utilizes four large primes and the XOR operation in key generation, while Nagaty is based on the complexity of calculating the nth partial sum of an infinite integer sequence. The system was developed using Python and designed to secure text files in *.docx format. Tests were conducted on text files with various character lengths to analyze the performance of the system. The results show that the processing time increases as the message length increases. The system also successfully performs the signcryption process and restores the contents of the text file to its original form with valid verification. In addition, the system proved to be resistant to a brute-force factorization attack, where a 35-bit key took more than an hour to crack.