Protecting data from malicious attacks during storage and transmission is the reason for using encryption. Encryption can be achieved by two methods-Transposition and Substitution. Transposition refers to changing the order of characters in a given text. On the other hand, substitution is the process of replacing each character of the plaintext with some other character. Using a combination of transposition and substitution for encryption leads to greater security when compared to using either of them separately. Vigenère Cipher is a poly-alphabetic cipher. It is based on the substitution technique which uses multiple substitution alphabets. In this paper, we introduce double columnar transposition on Vigenère Cipher to enhance its security making cryptanalysis difficult.

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RC4 is one of the most widely used stream ciphers which finds its application in many security protocols such as Wi-Fi Protocol Access (WPA) and Wired Equivalence Privacy (WEP). RC4 algorithm has several weaknesses. In order to overcome those weaknesses and enhance its security, numerous modifications have been suggested. These amendments destroy the basis of various cryptanalysis attacks on RC4. One such significant modification was the algorithm proposed by Jian Xie et al [1]. In this paper, we propose an enhancement to this algorithm by converting it into a product cipher and thereby enhancing its security.

Encryption is a process of hiding significant data so as to prevent unauthorized access and ensure confidentiality of data. It is widely used to transmit data across networks ensuring secure communication. This paper aims at improving the security and efficiency of image encryption by using a highly efficient shuffle based encryption algorithm and an equivalent decryption algorithm based on random values obtained by using pseudorandom number generator. Due to the immense amount of possibilities of instances of the encrypted image which can be generated by shuffling the pixels as a block (or on a pixel by pixel basis), the algorithm proves to be highly impervious to brute force attacks. The proposed algorithm has been examined using multiple analysis methods to support its robustness for achieving good results.