Implementation of Playfair Cipher and Least Significant Bit Algorithms in Digital Imagery

Message security is very important now. Because security is part of the privacy of someone who wants to protect messages from those who do not have the right to read or receive them. The method used for securing information messages with message encryption and decryption techniques is the Playfair Cipher algorithm combined with the Least Significant Bit (LSB) method. In this study it was found that the Playfair Cipher algorithm is quite safe in implementing cryptographic encryption or ciphertext because the playfair cipher has a level of appearance of letters that is so difficult to predict so that the ciphertext becomes a randomized collection of data. For the Least Significant Bit (LSB) steganography method in the insertion of a secret or embedded message it is difficult to guess in plain view the changes that occur between before and after the image is inserted are not too significant. Also see the value of the Peak-Signal-to-Noise ratio or PSNR can still be considered good quality due to> 30 decibels (dB). So the final result of the combination of the Playfair Cipher algorithm with the Least Significant Bit (LSB) method is quite good in securing messages.

Perancangan Aplikasi Penyandian Pesan Chat Client dan Server Berdasarkan Algoritma Spritz

The development of the computer world in the current era, the need to secure messages / data and for security in communication is very important. The author conducted this research aims to secure chat messages from client to server and vice versa. With this cryptographic technique used to convert chat messages into the form of certain codes with the intention that chat messages cannot be seen / read by anyone except people who have the right to read the chat messages. In this study, the Client and Server Message Chat encoding application is designed which implements the workings of encryption and decryption using the Spritz Algorithm. The results of this study are chat client and server message encoding applications with the Spritz algorithm that can encode confidential chat messages. This application was created using Microsoft Visual Basic 2008

Analysis of methods for organizing user rights in GNU\Linux systems

This article is about user’s rights to files or directories. The GNU\Linux systems have many great security features, but one of the most important is the file permissions system. Methods for organizing user rights in GNU\Linux systems, such as granting rights to each user individually and grouping users with the same or similar rights into groups, are discussed. The concept of operating system user and superuser is formed. The benefits of grouping users by access level have been identified. The criteria for dividing users into groups are analyzed, depending on the format of computer use, the structure of the organization that owns a particular computer and the number and positions of people who will work with it. Also, the benefit of the mechanism of organizing users into groups to manage service users of services running in the system is considered. It is said that any file and directory in Linux has an owner user and an owner group. That is, any file and directory belongs to some system user and some group. In addition, any file and directory has three access rights groups: one for the owner user, one for members of the owner group, and one for all other users on the system. Each group consists of the rights to read, write and execute the file for execution. The format of saving rights to a file or directory and the mechanism of checking access to a file or directory are considered. An explanation is given of what the right to read, the right to modify and the right to execute means for the file and for the directory. It is with the help of these sets of permissions that the permissions of files in linux are established. Each user can only have full access to files that he owns or those that he is allowed to access. Only the Root user can work with all files, regardless of their set of permissions.