Optimasi Enkripsi File dengan Menggunakan Skema Hybrid Cryptosistem sebagai Keamanan File

Abstract

Cryptography is a science that studies mathematical techniques related to information security aspects such as validity, data integrity, and data authentication. Cryptographic methods currently consist of two types, namely symmetric key cryptography and asymmetric key cryptography. In this study, the authors perform file optimization using a hybrid cryptosystem, namely modification of the Variably Modified Permutation Composition (VMPC) algorithm by adding a complementary method to the encryption and decryption process. Randomly generated keys will be optimized using Genetic Algorithm. The Variably Modified Permutation Composition (VMPC) algorithm is a symmetrical stream cipher algorithm similar to the RC4 cipher designed by Bartosz Zoltak. Variably Modified Permutation Composition (VMPC) algorithm is an extension of the VMPC one-way function which was developed into a byte-based encryption algorithm. In its use VMPC generates an 8-bit stream of permutations of 256 elements. The initial state of the permutation is calculated in the VMPC Key Scheduling. The ElGamal algorithm is a public key cryptography algorithm created by Taher ElGamal in 1984. This algorithm is generally used for digital signatures, but was later modified so that it can also be used for encryption and description. The security of this algorithm lies in the difficulty of calculating discrete logarithms on large modulo prime numbers so that attempts to solve this logarithm problem are very difficult. Genetic Algorithm generates an intermediate key which is unique every time the algorithm is run. The intermediate key is combined with Ciphertext at the first level which produces Ciphertext at the second level, up to Ciphertext at the third level. Attackers will not be able to carry out attacks like brute force, differential attacks or statistical attacks without having knowledge of the keys. From the results of the tests carried out, the more characters that are encrypted and decrypted, the longer it takes. In the avalanche effect test, the average value is 51.25% for the key without optimization, while 53.42% for the optimized key. The effect of key optimization using Genetic Algorithm has increased the value of the avalanche effect and has an effect on the result of changing the bits in the ciphertext.

Cryptography is a science that studies mathematical techniques related to information security aspects such as validity, data integrity, and data authentication. Cryptographic methods currently consist of two types, namely symmetric key cryptography and asymmetric key cryptography. In this study, the authors perform file optimization using a hybrid cryptosystem, namely modification of the Variably Modified Permutation Composition (VMPC) algorithm by adding a complementary method to the encryption and decryption process. Randomly generated keys will be optimized using Genetic Algorithm. The Variably Modified Permutation Composition (VMPC) algorithm is a symmetrical stream cipher algorithm similar to the RC4 cipher designed by Bartosz Zoltak. Variably Modified Permutation Composition (VMPC) algorithm is an extension of the VMPC one-way function which was developed into a byte-based encryption algorithm. In its use VMPC generates an 8-bit stream of permutations of 256 elements. The initial state of the permutation is calculated in the VMPC Key Scheduling. The ElGamal algorithm is a public key cryptography algorithm created by Taher ElGamal in 1984. This algorithm is generally used for digital signatures, but was later modified so that it can also be used for encryption and description. The security of this algorithm lies in the difficulty of calculating discrete logarithms on large modulo prime numbers so that attempts to solve this logarithm problem are very difficult. Genetic Algorithm generates an intermediate key which is unique every time the algorithm is run. The intermediate key is combined with Ciphertext at the first level which produces Ciphertext at the second level, up to Ciphertext at the third level. Attackers will not be able to carry out attacks like brute force, differential attacks or statistical attacks without having knowledge of the keys. From the results of the tests carried out, the more characters that are encrypted and decrypted, the longer it takes. In the avalanche effect test, the average value is 51.25% for the key without optimization, while 53.42% for the optimized key. The effect of key optimization using Genetic Algorithm has increased the value of the avalanche effect and has an effect on the result of changing the bits in the ciphertext.