Bitcoin was not forged in a vacuum. These works serve to contextualize Bitcoin into the broader story of cryptography and freedom.

Extending SAT Solvers to Cryptographic Problems

2009 | Mate Soos, Karsten Nohl, Claude Castelluccia – University of Virginia

Cryptography ensures the confidentiality and authenticity of information but often relies on unproven assumptions. SAT solvers are a powerful tool to test the hardness of certain problems and have successfully been used to test hardness assumptions. This paper extends a SAT solver to efficiently work on cryptographic problems. The paper further illustrates how SAT solvers process cryptographic functions using automatically generated visualizations, introduces techniques for simplifying the solving process by modifying cipher representations, and demonstrates the feasibility of the approach by solving three stream ciphers.

To optimize a SAT solver for cryptographic problems, we extended the solver’s input language to support the XOR operation that is common in cryptography. To better understand the inner workings of the adapted solver and to identify bottlenecks, we visualize its execution. Finally, to improve the solving time significantly, we remove these bottlenecks by altering the function representation and by pre-parsing the resulting system of equations.

The main contribution of this paper is a new approach to solving cryptographic problems by adapting both the problem description and the solver synchronously instead of tweaking just one of them. Using these techniques, we were able to solve a well-researched stream cipher 26 times faster than was previously possible.


On the Origins of Money

17 November 2009 | Carl Menger

Written in the same year that he testified before the Currency Commission in Austria-Hungary, and published in English in 1892, Carl Menger explains that it is not government edicts that create money but instead the marketplace. Individuals decide what the most marketable good is for use as a medium of exchange. “Man himself is the beginning and the end of every economy,” Menger wrote, and so it is with deciding what is to be traded as money.


The Ethics of Money Production

22 October 2008 | Jörg Guido Hülsmann

This pioneering work by Jörg Guido Hülsmann, professor of economics at the University of Angers in France and the author of Mises: The Last Knight of Liberalism, is the first full study of a critically important issue today: the ethics of money production.

By “money production,” the author is speaking not in the colloquial sense of the phrase “making money,” but rather the actual production of money as a commodity in the whole economic life. The choice of the money we use in exchange is not something that needs to be established and fixed by government.

In fact, his thesis is that a government monopoly on money production and management has no ethical or economic grounding at all. Legal tender laws, bailout guarantees, tax-backed deposit insurance, and the entire apparatus that sustains national monetary systems, has been wholly unjustified. Money, he argues, should be a privately produced good like any other, such as clothing or food.


Applications of SAT Solvers to Cryptanalysis of Hash Functions

August 2006 | Ilya Mironov, Lintao Zhang

Several standard cryptographic hash functions were broken in 2005. Some essential building blocks of these attacks lend themselves well to automation by encoding them as CNF formulas, which are within reach of modern SAT solvers. In this paper we demonstrate effectiveness of this approach. In particular, we are able to generate full collisions for MD4 and MD5 given only the differential path and applying a (minimally modified) off-the-shelf SAT solver. To the best of our knowledge, this is the first example of a SAT-solver-aided cryptanalysis of a non-trivial cryptographic primitive. We expect SAT solvers to find new applications as a validation and testing tool of practicing cryptanalysts.


The Case for Privacy

2005 | David D. Friedman


Scarce Objects

2004 | Nick Szabo


Improving Time Stamping Schemes: A Distributed Point of View

2002 | Alban Gabillon, Kaouther Blibech, Pierre Liardet, and Alexis Bonnecaze


A Formal Language for Analyzing Contracts

2002 | Nick Szabo


The Sybil Attack

2002 | John R. Douceur


Using Walk-SAT and Rel-SAT for Cryptographic Key Search

1999 | Fabio Massacci, Published in: IJCAI’99 Proceedings of the 16th international joint conference on Artifical intelligence – Volume 1, Pages 290-295

Computer security depends heavily on the strength of cryptographic algorithms. Thus, cryptographic key search is often THE search problem for many governments and corporations.

In the recent years, AI search techniques have achieved notable successes in solving “real world” problems. Following a recent result which showed that the properties of the U.S. Data Encryption Standard can be encoded in propositional logic, this paper advocates the use of cryptographic key search as a benchmark for propositional reasoning and search. Benchmarks based on the encoding of cryptographic algorithms optimally share the features of “real world” and random problems.

In this paper, two state-of-the-art AI search algorithms, Walk-SAT by Kautz & Selman and Rel-SAT by Bayardo & Schrag, have been tested on the encoding of the Data Encryption Standard, to see whether they are up the task, and we discuss what lesson can be learned from the analysis on this benchmark to improve SAT solvers.

New challenges in this field conclude the paper.


Confidential Auditing

1998 | Nick Szabo


The Geodesic Market

April 1998 through December 1999 | Robert Hettinga


Formalizing and Securing Relationships on Public Networks

1997 | Nick Szabo


The Idea of Smart Contracts

1997 | Nick Szabo


Negative Reputation

1996 | Nick Szabo


Money is Memory

October 1996 | Federal Reserve Bank of Minneapolis – Narayana R. Kocherlakota

This paper examines the sts of feasible allocations in a large class of economic environments in which commitment is impossible. The main proposition proves that any allocation that is feasible in an anvironment, the converse may or may not be true. Hence, from a technological point of view, money is equivalent to a primative form of memory.


A Declaration of the Independence of Cyberspace

8 February 1996 | John Perry Barlow


Smart Contracts Glossary

1995 | Nick Szabo


For-Pay Remailers

28 October 1994 | Hal Finney


The Cyphernomicon

10 September 1994 | Timothy C. May

In a FAQ format, the document outlines some of the ideas behind, and the effects of, crypto-anarchism.


Cyberspace, Crypto Anarchy, and Pushing Limits

3 April 1994 | Timothy C. May

This messages touches on two topics of recent interest (to some) here:

– Setting up payment systems for message transmission, to handle the issues of “mailbombing” and “flooding” in a more natural way (locality of reference, user of a service pays, avoidance of the “Morris Worm” explosion effects which could’ve happened with Detweiler bombed us, as Hal noted).
– The general issue of “Cyberspace.” This lies at the root of some recent disagreements here, and is worthy of more discussion. Crypto will make this a very real cusp issue in the next several years.


PGP Web of Trust Misconceptions

30 March 1994 | Hal Finney


Politics vs Technology

2 January 1994 | Hal Finney


The Cypherpunk Manifesto

9 March 1993 | Eric Hughes

A cypherpunk is any activist advocating widespread use of strong cryptography and privacy-enhancing technologies as a route to social and political change.


The Crypto Anarchist Manifesto

22 Nov 1992 | Timothy C. May

Crypto-anarchism (or crypto-anarchy) is a form of anarchy accomplished through computer technology.[1] Crypto-anarchists employ cryptographic software to evade persecution and harassment while sending and receiving information over computer networks, in an effort to protect their privacy, their political freedom, and their economic freedom.


The Machinery of Freedom (2nd Edition)

1989 | David D. Friedman


The Mystery of Banking

1983 | Murray N. Rothbard

The key to the book is that, following his mentor Ludwig von Mises, he integrates monetary theory with the basic principles of value theory that apply to all goods and services. He begins with a discussion of supply and demand. Once you understand how prices are determined in a free market, you are in a position to understand how the same principles apply to the demand and supply of money.


Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups

1982 | David Chaum

A number of organizations who do not trust one another can build and maintain a highly-secured computer system that they can all trust (if they can agree on a workable design). A variety of examples from both the public and
private sector illustrate the need for these systems. Cryptographic techniques make such systems practical, by allowing stored and communicated data to be protected while only a small mechanism, called a vault, need be physically secured. Once a vault has been inspected and sealed, any attempt to open it will cause it to destroy its own information content, rendering the attack useless. A decision by a group of trustees can allow such a vault-or even a physically destroyed vault -to be re-established safely.


Secrecy, Authentication, and Public Key Systems

June 1979 | Ralph C. Merkle


New Directions in Cryptography

November 1976 | Whitfield Diffie and Martin E. Hellman

Two kinds of contemporary developments in cryptography are examined. Widening applications of teleprocessing have given rise to a need for new types of cryptographic systems, which minimize the need for secure key distribution channels and supply the equivalent of a written signature. This paper suggests ways to solve these currently open problems. It also discusses how the theories of communication and computation are beginning to provide the tools to solve cryptographic problems of long standing.


What Has Government Done to Our Money?

15 June 1963 | Murray N. Rothbard

Rothbard boils down the Austrian theory to its essentials. The book also made huge theoretical advances. Rothbard was the first to prove that the government, and only the government, can destroy money on a mass scale, and he showed exactly how they go about this dirty deed. Rothbard shows precisely how banks create money out of thin air and how the central bank, backed by government power, allows them to get away with it. He shows how exchange rates and interest rates would work in a true free market. When it comes to describing the end of the gold standard, he is not content to describe the big trends. He names names and ferrets out all the interest groups involved.


Human Action: A Treatise on Economics

14 September 1949 | Ludwig von Mises

The masterpiece first appeared in German in 1940 and then disappeared, only to reappear in English in 1949. It was a sensation, the largest and most scientific defense of human freedom ever published. As is well known, Mises’s book is the best defense of capitalism ever written. It covers basic economics through the most advanced material. Reading this book is the best way you could ever dream up to learn economics. Every attempt to study economics should include a thorough examination of this book.


Back to University Archives