Cryptography

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 explores the known VoIP related vulnerabilities and suggests solution to various security issues. This paper tries to reduce the gap between the vulnerabilities, detection and solutions to VoIP security issues. Understanding this gap will help to identify what issues need to be addressed in the future development of VoIP applications? This paper provides a solution to denial of service attacks through network modeling and a solution to man in middle attacks using Elliptic Curve Encryption. The use of ECC proposed in various papers is limited to key exchange and authentication algorithms, not encryption. This paper also provides an approach to convert a plain text message in to elliptic curve points, which can further be used to implement Elliptic Curve Encryption/Decryption algorithms.

Recently 3G technology has grown rapidly
and is becoming a medium of choice for
communication. All elements of multimedia (text image
audio and video) are used. In this era, network security
has become an issue of importance, on which a lot of
research is going on. This paper presents the
implementation of ECC by first transforming the audio
file into an affine point on the Elliptic Curve (EC), over
the finite field GF(p). In ECC we normally start with an
affine point called Pm(x,y) which lies on the elliptic
curve. In this paper we illustrate the process of
encryption/decryption for audio file. It is almost
infeasible to attempt a brute force attack to break the
cryptosystem using ECC.

We propose a framework for organizing and classifying research results in the active field of secure multiparty computation (MPC). Our systematization of secure computation consists of (1) a set of definitions circumscribing the MPC protocols to be considered; (2) a set of quantitative axes for classifying and comparing MPC protocols; and a knowledge base of propositions specifying the known relations between axis values. We have classified a large number of MPC protocols on these axes and developed an interactive tool for exploring the problem space of secure computation. We also give examples of how this systematization can be put to use to foster new research and the adoption of MPC for real-world problems.

We consider a scenario for data outsourcing that supports performing database queries in the following three-party model: a client interested in making database queries, a data owner providing its database for client access, and a server (e.g., a cloud server) holding the (encrypted) outsourced data and helping both other parties. In this scenario, a natural problem is that of designing efficient and privacy-preserving protocols for checking compliance of a client’s queries to the data owner’s query compliance policy. We propose a cryptographic model for the study of such protocols, defined so that they can compose with an underlying database retrieval protocol (with no query compliance policy) in the same participant model. Our main result is a set of new protocols that satisfy a combination of natural correctness, privacy, and efficiency requirements. Technical contributions of independent interest include the use of equality-preserving encryption to produce highly practical symmetric-cryptography protocols (i.e., two orders of magnitude faster than "Yao-like" protocols), and the use of a query rewriting technique that maintains privacy of the compliance result.