Abstract: Security of the digital information is becoming primary concern prior to transmitting the information itself via some media. Information security means protecting information and information systems from unauthorized access, use, disclosure, disruption, modification or destruction. In this paper, a public key method of Steganography is proposed under standard cryptographic assumptions. The byte location in LSB of which the secret bit is to be embedded is found out by public key of the receiver and receiver apply private key of itself to reconstruct the secret message following RSA assumptions. General Terms time of hiding based on a particular public key Steganography, Security. Keywords Communication, Security, Steganography 1. INTRODUCTION Steganography is a technology that hides a message within an object, a text, or a picture. It is often confused with cryptography, not in name but in appearance and usage. The easiest way to differentiate the two is to remember steganography conceals not only the contents of the message but also the mere existence of a message. The original steganographic applications used “null ciphers” or clear text. A null cipher conveys that the message has not been encrypted in any way, whether it is using basic character shifting, substitution or advanced modern day encryption algorithm. So, the message is often in plain view but for a reason can either not be detected as being present or cannot be seen once detected. As is common with cryptography, steganography has its roots in military and government applications and has advanced in ingenuity and complexity. Steganography is the science of hiding secret information by means of some carrier file [1]. The secret information in general is embedded into some media file like image or audio and thus it is transmitted so as to prevent an opponent from guessing that some secret information is being transmitted. So, the main objective of Steganography is not to let the opponent guess that any kind of information apart from the media file itself is transmitted. In spatial domain of Steganography by using Image as the carrier file, we, in general, invert the Least Significant Bit of a particular byte of the carrier image to embed a particular bit of Secret message [2,3,4]. This method is known as LSB (Least Significant Bit) masking method of Steganography. In this paper, a public key method of Steganography is proposed under RSA cryptographic assumptions. In the proposed algorithm, RSA is used not to encrypt the secret message but to find the exact Byte location of the carrier file, in LSB of which a particular bit of the secret message is to be embedded. For a particular bit of the message file, we employ RSA encryption algorithm to generate a cipher. The LSB of the Red or Green or Blue value of a particular pixel represented by the cipher is then inverted only if the particular bit of the secret message is one. Likewise, we can embed the entire secret message into the carrier file and thereby we can send the embedded file called stego image and the carrier file to intended recipient. Upon receiving, recipient can apply XOR operation on the carrier image and the stego image to find the inverted LSBs. Then applying RSA Decryption algorithm on the location of a particular inverted LSB, we get the original position of the bit in the message file and thus can reconstruct the message file. Thus, this algorithm scatters the information at the -private key combination.

Abstract: Transposition ciphers are a class of historical encryption algorithms based on rearranging units of plaintext according to some fixed permutation which acts as the secret key. This paper presents a new investigation for cryptanalysis transposition cipher based on Particle Swarm Optimization (PSO). PSO is utilized for the automatic recovery of the key, and hence the plaintext, from only the cipher text. Based upon a mathematical model of the social interactions of swarms, the algorithm has been shown to be effective at finding good solutions. Experimental results show the ability of PSO in finding the correct secret key which is used to recover the plaintext.

Abstract: Multimedia data encryption attempts to prevent unauthorized disclosure of confidential multimedia information in transit or storage. Security of multimedia files attracts more and more attention and many encryption methods have been proposed in literature. If we call a multimedia data stream (message) plaintext , the process of transforming the plaintext into unintelligible data stream is referred to as multimedia encryption (MME) where the encrypted message (data stream) is often named ciphertext. The process of transforming the ciphertext back into plaintext is termed decryption. We propose a new block cipher based on randomized key of size n × n where n is the block size and the block undergoes n2 iterations with the plaintext. Every iteration generates the pseudo cipher text. The encryption process generate the ciphertext C with the help of the randomized key. The decryption apply the key in reverse order on the cipher text, to get back the plain text. This work deals with the problem of efficient multimedia data encryption.

Abstract: In this article, we design a stream cipher based on the the conjugates of quasigroups. According to the analysis given in the article the method is extremely secure. Beside that, the plaintext and its cipher text are of the same length, and the stream cipher needs small storage in memory since one quasigroup can be used as three different quasigroups.

Abstract: We describe the background of the Zodiac killer's cipher, and present a strategy for how to attack the unsolved Z340 cipher We present evidence that there is a high degree of non-randomness in the sequence of ciphertext symbols in this cipher, suggesting it has been constructed in a systematic way Next, we use this information to design a tool for solving the Zodiac ciphers Using this tool we are able to re-solve the known Z408 cipher

Abstract: Recently, a new image encryption scheme with compound chaotic sequence cipher shifting dynamically was proposed. In this Letter, the cryptosystem is analyzed and some flaws are pointed out. Then a chosen plaintext attack is described and some remedial modifications are suggested.

Abstract: Symmetric key crypto-systems use a single key to encrypt and decrypt data to create a secure communication over an insecure channel. Traditionally, this has been accomplished by creating a sequence of seemingly random numbers from the key and combining the sequence with the intended plaintext message. This method has been effective, with variations and iterations, for almost forty years. This dissertation presents a new variation of symmetric cipher based on convolutional codes. The method creates a large amount of valid parity from random input into a very large convolutional encoder and combines the output with a modified plaintext message. The decoder removes the valid parity by using a syndrome former that acts as an annihilator for the valid parity while revealing the intended plaintext message. This method, called LInCC, leverages the property of local invertibility to create a usable instance of a convolutional encoder that combines a large memory value and/or a high rate to create a very complex encoder. With the increased memory and rates the number of valid encoder choices that act as keys for the system increases at an exponential rate. The system can be made more secure by increasing the amount of memory or increasing the choice of possible coding rates. The LInCC system is a new type of cipher. The LInCC cipher has the potential to provide more security than most current ciphers. The ability to increase the ciphers strength exponentially by increasing the memory linearly allows the system to become more secure. The best known brute force attack would require more than 2900 key attempts for a 113 byte key. On the other hand, LInCC uses a single fixed key for multiple ciphertexts. This may prevent certain modes of operation from being effective. It can also expand the ciphertext to more than double the size of the original plaintext message. This may impact the effectiveness of the cipher. However, we believe that in some situations, such as streaming or downloading protected video content, this overhead may be quite acceptable.