300 research outputs found
A proposed hybrid cryptography algorithm based on GOST and salsa (20)
Security concepts are frequently used interchangeably. These concepts are interrelated and share similar objectives for the protection of privacy, credibility, and access to information; however, there are some slight differences between them. Such variations lie mostly in the subject matter approach, the approaches used, and the focus fields. With the intention of protecting data in contradiction of unauthorized or unintentional disclosure, cryptography is used during transit (electronic or physical) and when data is stored. In the course of the past few years, some block ciphers and stream ciphers have been proposed. These block ciphers take encryption method that uses Substitution-Permutation and Feistel network structure while stream ciphers choose a onetime method. GOST encryption is based on the confidentiality of the secret key. However, it leads to the same ciphertext being generated when the encryption program is used with the same key for the plain text. Reproduction of messages can thus easily be identified by an opponent that is a weak link in any communication. In this paper, proposed a hybrid encryption method based on GOST block cipher and Salsa stream cipher to provide proper security with as high hardness randomly enhances the five standard tests and modifies key schedule as secure operations. The downside of the GOST algorithm is a simple key schedule so that in certain circumstances be the weak point of the method of cryptanalysis as related-key cryptanalysis. However, this resolved by the proposed method by passing the keys of GOST to Salsa stream to have the right combination and more robustness security. Its need for 2256 probable keys to breaking keys that, because of its uncomfortable procedure in this situation, is to be not used brute force attack. Correspondingly, five standard tests successfully surpassed the randomness of a proposed method
Cryptanalysis of Simplified-AES using Particle Swarm Optimisation
Particle swarm optimisation (PSO) based cryptanalysis has gained much attention due to its fast convergence rate. This paper proposes a PSO-based cryptanalysis scheme for breaking the key employed in simplified-advance encryption standard (S-AES). The cost function is derived using letter frequency analysis. The novelty in our approach is to apply ciphertext-only attack for an S-AES encryption system, where we obtained the key in a minimum search space compared to the Brute-Force attack. Experimental results prove that PSO can be used as an effective tool to attack the key used in S-AES.Defence Science Journal, 2012, 62(2), pp.117-121, DOI:http://dx.doi.org/10.14429/dsj.62.77
Halka: A Lightweight, Software Friendly Block Cipher Using Ultra-lightweight 8-bit S-box
This paper presents the design of a lightweight, yet software friendly, block cipher. Most of the lightweight block ciphers are nibble-oriented as the implementation of a 4-bit S-box is much more compact than an 8-bit S-box. This paper uses a novel implementation of multiplicative inverse for 8-bit S-boxes using LFSR requiring only 138 gate-equivalent. With this powerful scheme, we design a lightweight block cipher competitive with existing standards in terms of hardware gate equivalent first time using an 8-bit S-box
Dynamic block encryption with self-authenticating key exchange
One of the greatest challenges facing cryptographers is the mechanism used
for key exchange. When secret data is transmitted, the chances are that there
may be an attacker who will try to intercept and decrypt the message. Having
done so, he/she might just gain advantage over the information obtained, or
attempt to tamper with the message, and thus, misguiding the recipient.
Both cases are equally fatal and may cause great harm as a consequence.
In cryptography, there are two commonly used methods of exchanging secret
keys between parties. In the first method, symmetric cryptography, the key is
sent in advance, over some secure channel, which only the intended recipient
can read. The second method of key sharing is by using a public key exchange
method, where each party has a private and public key, a public key is shared
and a private key is kept locally. In both cases, keys are exchanged between
two parties.
In this thesis, we propose a method whereby the risk of exchanging keys
is minimised. The key is embedded in the encrypted text using a process
that we call `chirp coding', and recovered by the recipient using a process
that is based on correlation. The `chirp coding parameters' are exchanged
between users by employing a USB flash memory retained by each user. If the
keys are compromised they are still not usable because an attacker can only
have access to part of the key. Alternatively, the software can be configured
to operate in a one time parameter mode, in this mode, the parameters
are agreed upon in advance. There is no parameter exchange during file
transmission, except, of course, the key embedded in ciphertext.
The thesis also introduces a method of encryption which utilises dynamic blocks, where the block size is different for each block. Prime numbers are
used to drive two random number generators: a Linear Congruential Generator
(LCG) which takes in the seed and initialises the system and a Blum-Blum
Shum (BBS) generator which is used to generate random streams to encrypt
messages, images or video clips for example. In each case, the key created is
text dependent and therefore will change as each message is sent.
The scheme presented in this research is composed of five basic modules. The
first module is the key generation module, where the key to be generated is
message dependent. The second module, encryption module, performs data
encryption. The third module, key exchange module, embeds the key into
the encrypted text. Once this is done, the message is transmitted and the
recipient uses the key extraction module to retrieve the key and finally the
decryption module is executed to decrypt the message and authenticate it.
In addition, the message may be compressed before encryption and decompressed
by the recipient after decryption using standard compression tools
A SUGGESTED SUPER SALSA STREAM CIPHER
Salsa (20) cipher is speedier than AES cipher and its offered superior security. Salsa (8) and Salsa (12) are specifiedfor apps wherever the grade of security is less necessary than speed. The concept of this research is to suggest super salsakeystream utilizing various volumes matrices size (array (4, 4), array (4, 8), array (4, 16)) are used to increase the complexity ofkey stream and make it more reluctant to linear and differential attacks. Furthermore, in each iteration, the diffusion ofgenerated keystream will increase due the effect of changing the volume acting for one element of the array is not fixed. Thegenerated keys of the suggested Super SALSA keystream are depicted as simple operations and a high hardiness randomlykeystream by exceeding the five benchmark tests. Likewise, it's presenting a situation of equilibrium between complexity andspeed for Salsa (8, 12 and 20)
- …