Hybrid Cryptosystems MRC-4 Algorithm and RSA Dual Modulus to Secure Data

Cryptography is very important when we talk about the security of data. Cryptography is a science that studies techniques, both mathematical and intuitive, related to aspects of data security. Along with the development of cryptography, technological developments are also developing very rapidly. There is a lot of data theft and lack of efficiency in maintaining data security, in this case it is very important to maintain the security of data and information. This research is designed to provide a solution to this problem by using Hybrid cryptography. Hybrid in this research combines the MRC4 and RSA Dual Modulus algorithms. The MRC4 algorithm is a stream cipher algorithm whose system security depends on generating a stream of key bits (keystream), while the RSA Dual Modulus algorithm is an asymmetric algorithm variant of RSA whose security lies in the difficulty of factoring large numbers into prime factors but this algorithm takes a long time in the encryption process when compared to the MRC4 algorithm. In the research process, the MRC4 algorithm is used to encrypt the sender's message and the RSA Dual Modulus algorithm will encrypt the key from MRC4, then the results of the message and key encryption process will be sent to the message recipient. After the recipient gets the plaintext and key, the key is first decrypted using the RSA Dual Modulus algorithm to produce a key that can decrypt the message using the MRC4 algorithm.