Encryption Algorithms

Algoritma ElGamal merupakan algoritma dalam kriptografi yang termasuk dalam kategori algoritma asimetris. Keamanan algoritma ElGamal terletak pada kesulitan penghitungan logaritma diskret pada bilangan modulo prima yang besar sehingga upaya untuk menyelesaikan masalah logaritma ini menjadi sangat sukar. Algoritma ElGamal terdiri dari tiga proses, yaitu proses pembentukan kunci, proses enkripsi dan proses dekripsi. Proses pembentukan kunci kriptografi ElGamal terdiri dari pembentukan kunci privat  dan pembentukan kunci public. Pada proses ini dibutuhkan sebuah bilangan prima aman  yang digunakan sebagai dasar pembentuk kunci public sedangkan sembarang bilangan acak digunakan sebagai pembentuk kunci privat. pada penelitian sebelumnya digunakan bilangan prima aman pada proses pembentukan kunci namun tidak dijelaskan alasan mengapa harus menggunakan bilangan prima aman tersebut. Penelitian ini mencoba membandingkan penggunaan bilangan prima aman dan bilangan prima tidak aman pada pembentukan kunci algoritma elgamal. Analisa dilakukan dengan  mengenkripsi dan dekripsi sebuah file dengan memvariasikan nilai bilangan prima aman dan bilangan prima tidak aman yang digunakan untuk pembentukan kunci public dan kunci privat. Dari hasil analisa dapat disimpulkan bahwa dengan menggunakan bilangan prima aman maupun bilangan prima tidak aman, proses pembentukan kunci, enkripsi dan dekripsi tetap dapat berjalan dengan baik, semakin besar nilai bilangan prima yang digunakan, maka kapasitas cipherteks juga semakin besar
Kata kunci : Kriptografi, Enkripsi, Dekripsi, Elgamal, Bilangan prima aman

Abstract

Elgamal algorithm is an algorithm in cryptography that is included in the category of asymmetric algorithms. The security of Elgamal algorithm lies in the difficulty in calculating the discrete logarithm on large number of prime modulo that attempts to solve this logarithm problem becomes very difficult. Elgamal algorithm is consists of three processes,  that are the key generating, encryption and decryption process. Key generation of elgamal cryptography process  is consisted of the formation of the private key and public key. In this process requires a secure prime number is used as the basis for forming public key while any random number used as forming of the private key. In the previous research is used secure prime number on key generating process but does not explain the reasons of using the secure primes. This research tried to compare using secure and unsecure primes in elgamal key generating algorithm. The analysis is done by encrypting and decrypting a file by varying the value of secure and unsecure of prime numbers that are  used on  generating of a public and a private key. From the analysis it can be concluded that using secure and unsecure of prime numbers, the process of key generating, encryption and decryption can run well, the greater value of prime numbers are used, the greater the capacity of the ciphertext.

Keywords: Cryptography, Encryption, Decryption, Elgamal, Secure Prime Value

This paper deals with one of the most critical computing problems which is Cryptography application, it is one of the problem that needs high computing power resources.
This paper introduces Symmetric Key Cryptography using DES (Data Encryption Standard) algorithm and employs a computing Grid for dealing with this problem. It presents a Grid for solving this problem that has been implemented by Alchemi which is an open source project developed at the University of Melbourne, which provides middleware for creating an enterprise grid computing environment by harnessing windows machines. The grid has been tested and results have been analyzed, there was an increase in performance over the single processor, but the performance improvement is limited by the I/O and communication overhead.

Advanced Encryption Standard (AES) algorithm is considered as a secured algorithm. Still, some security issues lie in the S-Box and the key used. In this paper, we have tried to give focus on the security of the key used. Here, the proposed modified algorithms for the AES have been simulated and tested with different chaotic variations such as 1-D logistic chaos equation, cross chaos equation as well as combination of both. For the evaluation purpose, the CPU time has been taken as the parameter. Though the variations of AES algorithms are taking some more time as compared to the standard AES algorithm, still the variations can be taken into consideration in case of more sensitive information. As we are giving more security to the key used for AES algorithm, our proposed algorithms are very much secured from unauthorized people.

In this paper two stage biometric data protection scheme is being proposed using permutation and substitution mechanism of the chaotic theory which is lossless in nature. Arnold transformation and Henon map is used to design an efficient encryption system. The encryption method is aimed at generating an encrypted image that will have statistical properties completely dissimilar from the original image analysis which will make it difficult for any intruder to decrypt the image. The performance of the method has been experimentally analyzed using statistical analysis and correlation based methods. Correlation coefficient analysis is done to evaluate the behavior of pixels in horizontal and vertical directions and the results are found to be encouraging. This protection scheme provides the ability to encrypt the data and secure it from unauthorized users. Upon decryption the data is completely recovered making this scheme a lossless and efficient method of biometric data security.

Encryption technology has been developed quickly and many image encryption methods have been used to protect confidential image data from unauthorized access.
In this paper, we introduce general quick brief introduction about cryptography, and then  propose a technique for image encryption/decryption by using the nature of FrFT in signals analysis, without use of special methods of encryption algorithms, based on multi-order Fractional Fourier Transform. Taking into account the security of the method used in the encryption work. In this research was to identify indicators to measure the security of the encryption Techniques: (i) sensitivity proposed Techniques for the encryption key can not get the original data only in the presence of this key, (ii) The complexity of the processes that are form internal proposed methods for encryption and decryption processes, and (iii) statistical analysis has been performed by calculating the histograms analysis, comparing with traditional Fourier transform the security system based on the fractional Fourier transform is protected by order of FrFT, it is can provides additional keys for encryption to make it more difficult to break. The keg is formed by combination of order of Fractional Fourier Transform and the matrix. Then, the encrypted image is obtained by the summation of different orders. Numerical simulation results are given to demonstrate this proposed method.

information. By using various techniques, many people are trying to access information that they are should not have access to. With the development of science, the application of information security techniques and data that have been
used in ancient times can be an alternative in securing data
communications. Cryptography is a science and art to maintain the security of messages sent from one place to another. RC4, one cryptographic algorithm, is widely
applied to encrypt information. Cryptography can still be broken even if the process takes time, cost and effort. Other data security techniques are also quite popular is
steganography. In contrast to cryptographic techniques, steganography can reduce suspicion because the message is disguised is hidden in another file. LSB is one of
steganographic methods. LSB widely applied to insert a secret message into a digital image.This software is made in order to secure the secret message into a digital image
using the RC4 algorithm and the method of LSB. The software is built using the waterfall model of software development.The results of the development of this software
has been able to secure the secret message in the form of text into a digital image with
a BMP format using RC4 algorithm and the method of LSB.

Masalah keamanan dan kerahasiaan data dan informasi merupakan suatu hal yang penting. Salah satu cara menjaga keamanan dan kerahasiaan data dan informasi adalah dengan teknik enkripsi dan dekripsi atau yang dikenal juga dengan kriptografi. Kriptografi adalah ilmu dan seni untuk menjaga keamanan pesan dengan cara mengubahnya menjadi suatu bentuk yang tidak dapat dikenali lagi. Salah satu algoritma kriptografi yang sering digunakan saat ini adalah Rijndael atau yang dikenal juga dengan AES (Advanced Encryption Standard). Kriptografi dapat diterapkan pada berbagai jenis file, salah satunya adalah citra digital. Perangkat lunak yang akan dibangun adalah perangkat lunak enkripsi dan dekripsi dengan algoritma Rijndael untuk citra digital. Perangkat lunak ini akan dibangun dengan menggunakan metode Waterfall. Hasil dari pembangunan perangkat lunak ini telah dapat mengimplementasikan algoritma kriptografi Rijndael untuk menjaga keamanan dan kerahasiaan citra digital dengan format file citra bitmap.