Topic
Cipher
About: Cipher is a research topic. Over the lifetime, 9409 publications have been published within this topic receiving 110309 citations. The topic is also known as: cypher & cryptographic algorithm.
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TL;DR: In this study, entropy and correlation coefficient are used as WDICA's fitness functions and the goal is to maximize the entropy and minimize correlation coefficients.
78 citations
11 Nov 1991
TL;DR: It is shown that an XOR profile with carefully placed zeroes is required in order to avoid some variant forms of differential cryptanalysis, and permutation P needs to be chosen to prevent easy propagation of a constant XOR value back into the same S-box.
Abstract: Differential Cryptanalysis is currently the most powerful tool available for analysing block ciphers, and new block ciphers need to be designed to resist it. It has been suggested that the use of S-boxes based on bent functions, with a flat XOR profile, would be immune. However our studies of differential cryptanalysis, particularly applied to the LOKI cipher, have shown that this is not the case. In fact, this results in a relatively easily broken scheme. We show that an XOR profile with carefully placed zeroes is required. We also show that in order to avoid some variant forms of differential cryptanalysis, permutation P needs to be chosen to prevent easy propagation of a constant XOR value back into the same S-box. We redesign the LOKI cipher to form LOKI91, to illustrate these results, as well as to correct the key schedule to remove the formation of equivalent keys. We conclude with an overview of the security of the new cipher.
77 citations
TL;DR: Wang et al. as discussed by the authors proposed a new visually secure image encryption scheme using adaptive-thresholding sparsification to greatly improve the quality of the reconstructed image and designed a new parallel CS technique to tremendously improve the processing efficiency.
77 citations
Proceedings Article•
01 Jan 2007
TL;DR: A system able to perform steganographic and cryptography at the same time using images as cover objects for steganography and as keys for cryptography is presented.
Abstract: In this paper we describe a method for integrating together cryptography and steganography through image processing. In particular, we present a system able to perform steganography and cryptography at the same time using images as cover objects for steganography and as keys for cryptography. We will show such system is an effective steganographic one (making a comparison with the well known F5 algorithm) and is also a theoretically unbreakable cryptographic one (demonstrating its equivalence to the Vernam Cipher).
76 citations
12 Oct 2015
TL;DR: This paper revisitswhite-box cryptography and proposes a family of white-box secure block ciphers SPACE with several novel features, including a high level of space hardness, which can mitigate the damage of having malware in security-critical systems such as networks processing top-secret data.
Abstract: The need for software security in untrusted environments is ever increasing. White-box cryptography aims to ensure the security of cryptographic algorithms when the attacker has full access to their implementations. However, there is no secure white-box implementation of standard block ciphers such as DES and AES known to date: All published techniques have been practically broken. In this paper, we revisit white-box cryptography and propose a family of white-box secure block ciphers SPACE with several novel features. The design of SPACE is such that the key-extraction security in the white box reduces to the well-studied problem of key recovery for block ciphers (AES in our example) in the standard black-box setting. Moreover, to mitigate code lifting, we introduce the notion of space hardness. It measures the difficulty of compressing the white-box implementation of a cipher, and quantifies security against code lifting by the amount of code that needs to be extracted from the implementation by a white-box attacker to maintain its functionality. SPACE includes several variants with different white-box code sizes. Therefore, it is applicable to a wide range of environments and use cases. One of the variants called N-SPACE can be implemented with different code sizes while keeping the cipher itself unchanged. SPACE offers a high level of space hardness: It is difficult to find a compact but still functional representation of SPACE given its white-box implementation. This property has several useful consequences for applications. First, it gets more challenging for a DRM attacker (e.g. in a pay TV setting) to scale a code-lifting attack and to distribute the break. Moreover, this paves the way for mass-surveillance resistant cryptography: If a large proportion of users dedicates a significant part of their computers' storage (e.g. HDD) to white-box SPACE implementations, it will be much more complex or even infeasible for governmental agencies to deal with the keys of all users simultaneously due to the limited storage available, forcing them to focus on targeted attacks instead. This consequence is especially important given Snowden's revelations on the extent of the mass surveillance practice by NSA and GCHQ. Finally, the usage of SPACE ciphers can mitigate the damage of having malware in security-critical systems such as networks processing top-secret data: As those are typically insulated from the Internet, the capacity of the communication channel from inside to outside the system is often limited, making it infeasible for Trojans to transmit the necessary key material.
76 citations