Untrusted Channel Research Articles

A chaos based image encryption algorithm using Rubik’s cube and prime factorization process (CIERPF)

A novel Rubik’s cube based pixel level scrambling and simple XOR based diffusion is proposed in this paper to safely transmit multimedia information (images) through an untrusted channel, such as adaptive image content (i.e., plain image related) based initial random value generation is introduced to achieve high plain image sensitivity in order to overcome plain image related attacks. From this random value, the initial vectors of Henon map is obtained and this is iterated to obtain the key sequences to be applied over the Rubik’s cube row and column confusion processes. Also, the same random seed is involved in the key generation process based on prime factorization to be applied in diffusion. For each and every encryption of different plain image, the random list is changed dynamically and it is shown that the CIERPF method is secure against differential attacks. The CIERPF method is checked against various simulations to illustrate the security level of the technique. From the simulations, it is shown that the proposed methodology has good key space, high key sensitivity, and uniform distribution of cipher image pixels. Also differential cryptanalysis is performed for the proposed cryptosystem to prove its effectiveness towards differential attacks.

Securing personal data in public cloud

ABSTRACTMore and more data are being stored in various cloud storages and they make it impossible to personally take care of data security, since most of these service providers do not offer any options for users to set up trusted encryption. We offer two types of solution to protect data, a client-side encryption and a security middleware. OpenWebCrypt is a browser extension designed to secure private data so it does not leave the client browser. Our security middleware, CrypStore PI offers a flexible solution to encrypt all the data that leaves the trusted LAN. By doing so, both guarantee that neither an attacker on the untrusted channel, nor the third-party external service provider has access to those. Furthermore, by separating the keys and the encryption itself from the user machines to dedicated hardware, CrypStore PI also improves the level of protection. Our goal is to offer easy to use, configurable and affordable solutions for personal users or small enterprises who would like to take responsibility for the protection of their data stored in public clouds. Because of the limited resources, we analysed the performance of today's most used symmetric key encryption algorithms to be able to recommend the best choice.

Encryption-Then-Compression Systems Using Grayscale-Based Image Encryption for JPEG Images

A block scrambling-based encryption scheme is presented to enhance the security of Encryption-then-Compression (EtC) systems with JPEG compression, which allow us to securely transmit the images through an untrusted channel provider, such as social network service providers. The proposed scheme enables the use of a smaller block size and a larger number of blocks than the conventional scheme. Images encrypted using the proposed scheme include less color information due to the use of grayscale images even when the original image has three color channels. These features enhance security against various attacks such as jigsaw puzzle solver and brute-force attacks. In an experiment, the security against jigsaw puzzle solver attacks is evaluated. Encrypted images were uploaded to and then downloaded from Facebook and Twitter, and the results demonstrated that the proposed scheme is effective for EtC systems.

Dynamic digest based authentication for client–server systems using biometric verification

Abstract The client authentication is a significant process in client–server systems. Such a process is highly secure when a client may be authenticated according to a set of unique verifiable data, i.e., biometric traits. However, biometric based systems with the low-cost, dense biometric sensors, and power of fast processing need a method of automatic client recognition for the robust client authentication. Such a method faces three challenges: (1) the effective recognition of the biometric patterns inputted to the system, (2) the provision of security to prevent the vulnerability of the system, and (3) the preparation of personal privacy. Many remote biometric authentication schemes have been developed to establish secure mutual communication between a client as a device node and server over an untrusted channel. By employing a secure remote biometric based authentication protocol, a client that acts in a node and a server that contains resources can authenticate each other in a secure and trustable manner. In our previous work, we proposed a digest based authentication method that preserves privacy of client’s biometric templates and authenticates the client securely by generating non-deterministic semi-digest. By reviewing and cryptanalyzing this method, in the current paper, we focus on the improvement of the method for providing the invulnerability against user anonymity and server masquerading attacks. We show that our improved scheme is secure against the attacks and prove its functionality features.

Image Manipulation Specifications on Social Networking Services for Encryption-then-Compression Systems

Encryption-then-Compression (EtC) systems have been proposed to securely transmit images through an untrusted channel provider. In this study, EtC systems were applied to social media like Twitter that carry out image manipulations. The block scrambling-based encryption schemes used in EtC systems were evaluated in terms of their robustness against image manipulation on social media. The aim was to investigate how five social networking service (SNS) providers, Facebook, Twitter, Google+, Tumblr and Flickr, manipulate images and to determine whether the encrypted images uploaded to SNS providers can avoid being distorted by such manipulations. In an experiment, encrypted and non-encrypted JPEG images were uploaded to various SNS providers. The results show that EtC systems are applicable to the five SNS providers.

Secure and Efficient Electronic Auction Scheme with Strong Anonymity

Most electronic auction schemes need trusted channels. If the communication channel is Incredible, trading parties' privacy information would be easily intercepted by an attacker. Some schemes can protect bidders’ privacy under untrusted channels, but these schemes usually use complex encryption technology, have poor efficiency. Established along the blind signature and one-way function, an electronic auction scheme is offered. The scheme needs not complex encryption and credible channel, has less computation, and is easy to program. So it can be used in the Internet large rang anonymous bid. Anonymity and security of all bidders, including lose bidder, have the same and important position in the proposed scheme, and are satisfied well too. Moreover, the proposed scheme has additional characteristics such as unforgeability, strong verifiability, non-repudiation, time limitation, fairness and high effectiveness.

Squeezed-state quantum key distribution upon imperfect reconciliation

We address the security of continuous-variable quantum key distribution with squeezed states upon the realistic conditions of noisy and lossy environment and limited reconciliation efficiency. Considering the generalized preparation scheme and clearly distinguishing between classical and quantum resources, we investigate the effect of finite squeezing on the tolerance of the protocol to untrusted channel noise. For a long-distance strongly attenuating channel and the consequent low reconciliation efficiency, we show that feasible limited squeezing is surprisingly sufficient to provide the security of Gaussian quantum key distribution in the presence of untrusted noise. We explain the effect by the behaviour of the Holevo quantity, which describes the information leakage and is effectively minimized by the squeezed states.

Feasibility of continuous-variable quantum key distribution with noisy coherent states

We address security of the quantum key distribution scheme based on the noisy modulation of coherent states and investigate how it is robust against noise in the modulation regardless of the particular technical implementation. As the trusted preparation noise is shown to be security breaking even for purely lossy channels, we reveal the essential difference between two types of trusted noise, namely sender-side preparation noise and receiver-side detection noise, the latter being security preserving. We consider the method of sender-side state purification to compensate the preparation noise and show its applicability in the realistic conditions of channel loss, untrusted channel excess noise, and trusted detection noise. We show that purification makes the scheme robust to the preparation noise (i.e., even the arbitrary noisy coherent states can in principle be used for the purpose of quantum key distribution). We also take into account the effect of realistic reconciliation and show that the purification method is still efficient in this case up to a limited value of preparation noise.

DISTARNET – A Distributed Archival Network

The goal of this work is to develop and establish an archival system for digital data with focus on long-term archival as required by archives and museums which preserve the audio-visual heritage of our time. The fundamental idea is that institutions with long-term archival needs of digital data collaborate in order to build a geographically distributed, Internet based archival system. It has been of primary concern in designing this system to minimizing the risk of data loss due to a catastrophic event (on a local or even regional scale such as a devastating earthquake) or false manipulation. In addition the archival network has to cope with the rapidly changing standards of information technology and preserve readability of the data beyond changes of software and hardware technology.The archival network will be implemented as a distributed, self-organizing and optimized peer-to-peer (P2P) network with a high redundancy. The data to be archived will be distributed in redundant copies among all participants' parties. It will be assumed that the data will be transported over untrusted channels and stored on untrusted nodes. Therefore, strong cryptography will be used to guarantee the integrity and privacy of the archived digital assets.The goal of this work is to establish an archival system for digital data with focus on long-term archival as required by archives and museums which preserve the audio-visual heritage of our time. The fundamental idea is that institutions with long-term archival needs of digital data (digitized cultural assets such as photographic collections, sound archives etc.) collaborate in order to build a geographically distributed, redundant Internet based archival system. Minimizing the risk of data loss due to a catastrophic event (on a local or even regional scale such as a devastating earthquake) or false manipulation is of primary concern in designing this system. Additionally the archival network has to cope with the rapidly changing standards of information technology and preserve readability of the data beyond changes of software and hardware technology.In order to achieve both goals, we propose a globally distributed storage network with high redundancy based on a peer-to-peer (P2P) architecture. The integrity and privacy of the data entrusted to the archival system is guaranteed by strong cryptography, especially private/public key encryption schemes. The archival network forms sort of a “closed user group” based on Internet technology where all relevant data is encrypted.