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.

Solved: the ciphers in book III of Trithemius's steganographia

Abstract: Book III of Trithemius's Steganographia (written ca. 1500) contains hidden cipher messages within what is ostensibly a work on magic. After almost 500 years these cryptograms have been detected and solved. (Since 1606 it was known that similar ciphers were present in Books I and II.) As a result the Steganographia can no longer be regarded as one of the main early modern demonological treatises but instead stands unambiguously revealed as the first book-length treatment of cryptography in Europe.

Grain of Salt --- an Automated Way to Test Stream Ciphers through SAT Solvers

Abstract: In this paper we describe Grain of Salt, a tool developed to automatically test stream ciphers against standard SAT solver-based attacks. The tool takes as input a set of configuration options and the definition of each filter and feedback function of the stream cipher. It outputs a problem in the language of SAT solvers describing the cipher. The tool can automatically generate SAT problem instances for Crypto-1, HiTag2, Grain, Bivium-B and Trivium. In addition, through a simple text-based interface it can be extended to generate problems for any stream cipher that employs shift registers, feedback and filter functions to carry out its work.

System for downloading program to general-purpose subscriber identification module

Abstract: A system comprises a USIM (1) capable of data read/write by a cellular telephone terminal (2) and having a predetermined program specification and cipher communication means, and a server (6) communicating with the USIM via the cellular telephone terminal and providing a program to the USIM in accordance with the predetermined program specification. The server creates and transmits a list of programs which can be offered in the program specification transmitted from the USIM. Upon reception of program information selected from the program list via the cellular telephone terminal, the server selects predetermined cipher communication means from a cipher communication means list transmitted from the USIM, encrypts the program, and downloads the program to the USIM.

Logical Cryptanalysis as a SAT Problem ? Encoding and Analysis of the U.S. Data Encryption Standard

Abstract: Cryptographic algorithms play a key role in computer security and the formal analysis of their robustness is of utmost importance. Yet, logic and automated reasoning tools are seldom used in the analysis of a cipher, and thus one cannot often get the desired formal assurance that the cipher is free from unwanted properties that may weaken its strength. In this paper, we claim that one can feasibly encode the low-level properties of state-of-the- art cryptographic algorithms as SAT problems and then use efficient automated theorem-proving systems and SAT-solvers for reasoning about them. We call this approach logical cryptanalysis. In this framework, for instance, finding a model for a formula encoding an algorithm is equivalent to finding a key with a cryptanalytic attack. Other important properties, such as cipher integrity or algebraic closure, can also be captured as SAT problems or as quantified boolean formulae. SAT benchmarks based on the encoding of cryptographic algorithms can be used to effectively combine features of "real-world" problems and randomly generated problems. Here we present a case study on the U.S. Data Encryption Standard (DES) and show how to obtain a manageable encoding of its properties. We have also tested three SAT provers, TABLEAU by Crawford and Auton, SATO by Zhang, and rel-SAT by Bayardo and Schrag, on the encoding of DES, and we discuss the reasons behind their different performance. A discussion of open problems and future research concludes the paper.

Advanced modes in AES: Are they safe from power analysis based side channel attacks?

Abstract: Advanced Encryption Standard (AES) is arguably the most popular symmetric block cipher algorithm. The commonly used mode of operation in AES is the Electronic Codebook (ECB) mode. In the past, side channel attacks (including power analysis based attacks) have been shown to be effective in breaking the secret keys used with AES, while AES is operating in the ECB mode. AES defines a number of advanced modes (namely Cipher Block Chaining - CBC, Cipher Feedback - CFB, Output Feedback - OFB, and Counter - CTR) of operations that are built on top of the EBC mode to enhance security via disassociating the encryption function from the plaintext or the secret key used. In this paper, we investigate the vulnerabilities against power analysis based side channel attacks of all such modes of operations, implemented on hardware circuits for low power and high speed embedded systems. Through such an investigation, we show that AES is vulnerable in all modes of operations against Correlation Power Analysis (CPA) attack, one of the strongest power analysis based side channel attacks. We also quantify the level of difficulty in breaking AES in different modes by calculating the number of power traces needed to arrive at the complete secret key. We conclude that the Counter mode of operation provides a balance in between area and power while maintaining adequate resistance for power analysis attacks than when used with other modes of operations. We show that the previous recommendations for the rate of change in the keys and vectors is grossly inadequate, and suggest that it must be changed at least every 2 10 encryptions in CBC mode and 2 12 encryptions in CFB, OFB and CTR modes in order to resist power analysis attacks.