Theoretical and practical efficiency aspects in cryptography

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The Cultural Contradictions of Cryptography

This dissertation examines the origins of political and scientific commitments that currently frame cryptography, the study of secret codes, arguing that these commitments took shape over the course of the twentieth century. Looking back to the nineteenth century, cryptography was rarely practiced systematically, let alone scientifically, nor was it the contentious political subject it has become in the digital age. Beginning with the rise of computational cryptography in the first half of the twentieth century, this history identifies a quarter-century gap beginning in the late 1940s, when cryptography research was classified and tightly controlled in the US. Observing the reemergence of open research in cryptography in the early 1970s, a course of events that was directly opposed by many members of the US intelligence community, a wave of political scandals unrelated to cryptography during the Nixon years also made the secrecy surrounding cryptography appear untenable, weakening the official capacity to enforce this classification. Today, the subject of cryptography remains highly political and adversarial, with many proponents gripped by the conviction that widespread access to strong cryptography is necessary for a free society in the digital age, while opponents contend that strong cryptography in fact presents a danger to society and the rule of law. I argue that cryptography would not have become invested with these deep political commitments if it had not been suppressed in research and the media during the postwar years. The greater the force exerted to dissuade writers and scientists from studying cryptography, the more the subject became wrapped in an aura of civil disobedience and public need. These positive political investments in cryptography have since become widely accepted among many civil libertarians, transparency activists, journalists, and computer scientists who treat cryptography as an essential instrument for maintaining a free and open society in the digital age. Likewise, even as opponents of widespread access to strong cryptography have conceded considerable ground in recent decades, their opposition is grounded in many of the same principles that defined their stance during cryptography’s public reemergence in the 1970s. Studying this critical historical moment reveals not only the origins of cryptography’s current politics, but also the political origins of modern cryptography

An asynchronous DES in contactless smartcard.

Siu, Pui-Lam.Thesis submitted in: August 2003.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.Includes bibliographical references (leaves 104-109).Abstracts in English and Chinese.list of figures --- p.5list of tables --- p.7acknowledgements --- p.8abstract --- p.9Chapter 1. --- introduction --- p.12Chapter 1.1 --- Smart Card --- p.12Chapter 1.1.1 --- What is a smart card? --- p.12Chapter 1.1.2 --- How is a smart card different from the magnetic stripe card that I carry in my wallet? --- p.13Chapter 1.1.3 --- Why are interoperability and enforced standards crucial to widespread adoption of smart cards? --- p.13Chapter 1.1.4 --- Contact vs Contactless --- p.14Chapter 1.1.5 --- How secure and confidential contactless smart cards are? --- p.14Chapter 1.1.6 --- Contactless Smart Card Application Contactless smart cards are widely used in commercial fields as stored-value and secure storage cards --- p.14Chapter 1.1.7 --- What are the major benefits that Contactless smart cards offer to consumers? --- p.16Chapter 1.2 --- Design Motivation --- p.16Chapter 1.3 --- RF Part Interface --- p.17Chapter 1.4 --- Potential Advantages of Using Asynchronous Circuit --- p.19Chapter 1.5 --- Design Methodology for Asynchronous Circuit --- p.23Chapter 1.5.1 --- Difficulty and limitation of asynchronous design --- p.27Chapter 1.5.2 --- Asynchronous pipeline --- p.28Chapter 2. --- background theory --- p.32Chapter 2.1 --- Description of DES --- p.32Chapter 2.1.1 --- Outline of the Algorithm --- p.33Chapter 2.1.2 --- Initial Permutation --- p.35Chapter 2.1.3 --- Key Transformation --- p.35Chapter 2.1.4 --- Expansion Permutation --- p.37Chapter 2.1.5 --- S-box Substitution --- p.38Chapter 2.1.6 --- P-Box Permutation --- p.41Chapter 2.1.7 --- Final Permutation --- p.42Chapter 2.1.8 --- Decrypting DES --- p.43Chapter 2.1.9 --- Security of DES --- p.43Chapter 2.1.10 --- Weak Keys --- p.43Chapter 2.1.11 --- Algebraic Structure --- p.46Chapter 2.1.12 --- Key Length --- p.46Chapter 2.1.13 --- Number of Rounds --- p.48Chapter 2.1.14 --- Design of the S-Boxes --- p.48Chapter 3. --- rf part --- p.50Chapter 3.1 --- Power On --- p.51Chapter 3.2 --- Power Induction --- p.52Chapter 3.3 --- Limiter and Regulator --- p.54Chapter 3.4 --- Demodulation --- p.56Chapter 3.5 --- Modulation --- p.57Chapter 4. --- asynchronous circuit theory --- p.58Chapter 4.1 --- Potential Problem of Classical Asynchronous Pipeline --- p.58Chapter 4.2 --- The New Handshake Cell --- p.58Chapter 4.3 --- The Modified Asynchronous Pipeline Architecture --- p.60Chapter 4.4 --- Asynchronous Circuit Comparison --- p.65Chapter 5 --- implementation --- p.67Chapter 5.1 --- DES Implementation --- p.67Chapter 5.1.1 --- Power estimation of the asynchronous DES --- p.70Chapter 5.1.2 --- Modified Circuit --- p.73Type One --- p.73Type two --- p.76Chapter 5.1.3 --- Interface --- p.79Chapter 5.1.4 --- Shift Unit --- p.80Chapter 5.1.5 --- Multiplexer Unit --- p.82Chapter 5.1.6 --- Compression Unit --- p.83Chapter 5.1.7 --- Expansion Unit --- p.84Chapter 5.1.8 --- Xor Unit --- p.85Chapter 5.1.9 --- S_box Unit --- p.86Chapter 5.1.10 --- P-box unit --- p.88Chapter 5.1.11 --- Latch unit --- p.89Chapter 5.1.12 --- Transmission Unit --- p.90Chapter 5.2 --- Floor Plan Design --- p.90Chapter 6. --- result and discussion --- p.93Chapter 6.1 --- Simulation Result --- p.93Chapter 6.2 --- Measurement --- p.97Chapter 6.3 --- Comparison --- p.101Chapter 6.4 --- Conclusion --- p.101Chapter 7. --- reference --- p.104Chapter 8. --- appendix --- p.110Chapter 8.1 --- RF Part Implementation --- p.110Chapter 8.1.1 --- Full wave rectifying circuit --- p.110Chapter 8.1.2 --- "Limiting Circuit," --- p.111Chapter 8.1.3 --- Regulator circuit --- p.113Chapter 8.1.4 --- Demodulation circuit --- p.113Chapter 8.1.5 --- Simulation of the RF part --- p.115Chapter 8.2 --- New Technology for Designing a RF Interface --- p.117Chapter 8.2 --- Block Diagrams --- p.11