Sign-Then-Encrypt Scheme Dengan Cramer-Shoup Cryptosystem dan Dissanayake Digital Signature

Abstract

Computer security is becoming increasingly important in today's technological development due to the continuous increase in security breaches. Many people are concerned about protecting data from unauthorized disclosure, modification, or destruction. There are many techniques for protecting data in this era by designing a good computer security system. One technique that can be used is cryptography. Cryptography is a technique based on mathematics to secure information such as confidentiality, integrity, and entity authentication. Therefore, this research will develop a sign-then-encrypt scheme using the Dissayanke digital signature scheme and the Cramer-Shoup algorithm. To analyze the security level of the developed scheme, the Avalanche effect will be used. Based on the execution time testing, the sign-then-encrypt process takes longer than the decrypt-then-verifying process because the sign-then-encrypt process requires time to generate prime numbers and keys. Avalanche effect testing on the Dissayanke digital signature and Cramer Shoup algorithm with various scenarios showed results with values greater than 50%. The Dissayanke digital signature and Cramer-Shoup algorithm comply the criteria for the avalanche effect because they changes in more than half of the bits when there is a change in the input bit.