A Review of Existing 4-bit Crypto S-box cryptanalysis Techniques and Two New Techniques with 4-bit Boolean Functions for Cryptanalysis of 4-bit Crypto S-boxes.

4-bit Linear Relations play an important role in Cryptanalysis of 4-bit Bijective Crypto S-boxes. 4-bit finite differences also a major part of cryptanalysis of 4-bit substitution boxes. Count of existence of all 4-bit linear relations, for all of 16 input and 16 output 4-bit bit patterns of 4-bit bijective crypto S-boxes said as S-boxes has been reported in Linear Cryptanalysis of 4-bit S-boxes. Count of existing finite differences from each element of output S-boxes to distant output S-boxes have been noted in Differential Cryptanalysis of S-boxes. In this paper a brief review of these cryptanalytic methods for 4-bit S-boxes has been introduced in a very lucid and conceptual manner. Two new Analysis Techniques, one to search for the existing Linear Approximations among the input Boolean Functions (BFs) and output BFs of a particular 4-bit S-Box has also been introduced in this paper. The search is limited to find the existing linear relations or approximations in the contrary to count the number existent linear relations among all 16 4-bit input and output bit patterns within all possible linear approximations. Another is to find number of balanced 4-bit BFs in difference output S-boxes. Better the number of Balanced BFs, Better the security

A review of cryptographic properties of S-boxes with Generation and Analysis of crypto secure S-boxes.

In modern as well as ancient ciphers of public key cryptography, substitution boxes find a permanent seat. Generation and cryptanalysis of 4-bit as well as 8-bit crypto S-boxes is of utmost importance in modern cryptography. In this paper, a detailed review of cryptographic properties of S-boxes has been illustrated. The generation of crypto S-boxes with 4-bit as well as 8-bit Boolean functions (BFs) and Polynomials over Galois field GF(p^q) has also been of keen interest of this paper. The detailed analysis and comparison of generated 4-bit and 8-bit S-boxes with 4-bit as well as 8-bit S-boxes of Data Encryption Standard (DES) and Advance Encryption Standard (AES) respectively, has incorporated with example. Detailed analysis of generated S-boxes claims a better result than DES and AES in view of security of crypto S-boxes

Foresight and flexibility in cryptography and voice over IP policy

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Political Science, 2008."February 2008."Includes bibliographical references (p. 235-248).This main question in this dissertation is under what conditions government agencies show foresight in formulating strategies for managing emerging technologies. A secondary question is when they are capable of adaptation. Conventional wisdom and most organization theory literature suggest that organizations are reactive rather than proactive, reluctant to change, and responsive only to threats to their core mission or autonomy. The technological, economic, social, political, and sometimes security uncertainties that often accompany emerging technologies further complicate decision-making. More generally, organizations must often make decisions under conditions of limited information while guarding against lock-in effects that can constrain future choices. The two cases examined in this dissertation suggest that contrary to conventional wisdom, organizations can show foresight and flexibility in the management of emerging technologies. Key factors that promote foresight are: an organizational focus on technology, with the emerging technology in question being highly relevant to the organization's mission; technical expertise and a recognition of the limits of that knowledge; and experience dealing with other emerging technologies. The NSA recognized the inevitability of mass market encryption early on and adopted a sophisticated strategy of weakening the strength of, reducing the use of, and slowing down the deployment of mass market encryption in order to preserve its ability to easily monitor communications. The Agency showed considerable tactical adaptation in pursuit of this goal. The FCC adopted a rather unusual policy of forbearance toward VoIP. The Commission deliberately refrained from regulating VoIP in order to allow the technology to mature, innovation to occur, uncertainties to resolve, and to avoid potential market distortions due to too early or suboptimally formulated regulation. Eventually, however, pressure from outside interests such as law enforcement forced the Commission to act.by Shirley K. Hung.Ph.D