| ICSA Guide to
Cryptography Randall Nichols $69.95 0-07-913759-8 |
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Cryptology is the study of creating codes and ciphers (cryptography) and decoding or deciphering codes and ciphers (cryptanalysis) when the system is not known. Cryptology would not be the science it is today without the contributions of different groups of people who have become part of its rich and fascinating history over the past several thousand years. David Kahn wrote the definitive history of cryptology in his book The Codebreakers. Dr. Bauer at University of Munich, in his thoroughly enjoyable book Decrypted Secrets - Methods and Maxims of Cryptology extended Kahns work to include European contributions. Nichols in his two volumes Classical Cryptography Course focused on the scientists and mathematicians involved in the science of cryptanalysis of codes, ciphers, and speech.
Mathematical disciplines have played an important part in the development and especially the current state-of-the-art efforts in cryptology. A list of the disciplines would include applied and theoretical statistics, number theory, group theory, combinatory logic, complexity theory, information theory, elliptical curves study and chaos theory. Cryptology is taught in major schools under the banner of applied mathematics and computer science. The computer scientist views cryptology as an important connection with respect to access to operating systems, databases, computer networks, and data transmission systems.
The list of contributors and their stories are exemplary--names such as Francois Viete; John Wallis of England; Rossignol of France; Auguste Kerckhoff of Holland; de Viarus, Valerio, Delastelle, Bazeries, General Givierge, all of France; Edgar Allen Poe, a rather misunderstood cryptographer and visionary; General Luigi Sacco in Italy, the American Master Cryptographer, who in 1920, introduced the Index of Coincidence and on whos brilliance the later day National Security Agency (NSA) placed its trust, William Frederick Friedman; Abraham Sinkov; Solomon Kullback; Lester S. Hill; Claude E. Shannon who gave us modern day information theory; Alan Turing in England; Hans Rohrbach from Germany; Marian Rejewski from Poland who originally broke ENIGMA ; Vannevar Bush ; Frank Lewis who defeated the Japanese Army codes in 1942-43; Maurits de Vries in the Netherlands; and Ernst S. Selmer in Norway.
Cryptographys influence on history is significant. For example, a small historical snapshot might include the following names:
Kerckhoff
Kerckhoff (AKA Jean-Guillaume-Hubert-Victor-Francois-Alexandre- Auguste Kerckhoff von Nieuwenhof) was not French or Dutch but Flemish. Kerckhoff was the first to separate the general system from the specific key. He perfected the theory of superimposition to solve polyalphabetic systems. He described the concepts of symmetry of position to glean more plain text from the cipher text. He invented the St-Cyr slide and named it after the French national military academy where he studied. "La Cryptographie militaire" gave the French a commanding lead in cryptography in World War I. He was the impetus for those that followed.
French Influences - Givierge, Valerio, de Viaris, Delastelle and Bazeries
General Givierge, a military commander, wrote an early and important textbook on cryptography called Course in Cryptography. Givierge published letter frequencies for French, German, English, Russian, Spanish, and Italian. They differ from the Master William F. Friedmans works. Friedman's works are more authoritative and based on significantly more modern plain text General Givierge borrowed from Paul Louis Eugene Valerio, a captain of Artillery who wrote in the Journal des Sciences militaires in 1892. Valerio published a book called "De la cryptographie" in 1895. The General also borrowed from de Viaris (aka Marquis Gaetan Henri Leon Viarizio di Lesegno) who is invented one of the first printing cipher devices, in 1874. The General may have included the work of the enigmatic Felix Marie Delastelle, who wrote Traite Elementaire de Cryptographie in 1902. Delastelle's most famous cipher is the bifid, which will be covered in a later section. Delastelle expanded Kerchoffs symmetry of position principles published in "La Cryptographie militarie" in 1883. Lastly, Etienne Bazeries influence on the General was important. Bazeries invented a cylinder device for polyalphabetic encipherment. De Viaris solved the Bazeries cylinder in 1893. Bazeries was miffed to say the least. In spite of this, his device was accepted for use by the U.S. Army as a field cipher device until 1922.
Rossignol
Rossignol served with a swashbuckling facility in the Court of Louis XIV. His cryptographic
successes gave him access to secrets of state and the court. The poet Boisrobert (who originated the idea of "Academie Francaise") wrote the first poem ever written to a cryptologist entitled "Epistres en Vers." He was the court cryptologist of France in the time when Moliere was her dramatist, Pascal her philosopher, La Fontaine her fabulist and the supreme autocrat of the world her monarch.
Rossignol's technical improvements to the nomenclator (a two-part code) systems of the time were quite important. When Rossignol began his career, nomenclators were one-part, listing both the plain and the code elements in alphabetical order or numerical order if the code was numerical. Plain and code paralleled each other. This arrangement existed since the beginning of the Renaissance. Rossignol destroyed the parallel arrangements and mixed the code elements relative to the plain. Two lists were required, one in which the plain elements were in alphabetical order and the code elements were randomized. The second facilitated decoding in which the code elements were alphabetized and the plain equivalents were disarranged. The two tables were called 'tables a chiffrer' and 'tables a dechiffrer'. The two part codes are similar to a bilingual dictionary. The two-part construction spread rapidly to other countries and the nomenclator systems grew in numbers and size.
His son Bonaventure and his grandson Antoine-Bonaventure both carried on the tradition started by their father. Both were raised from King's counselor to president of the Chamber of Accounts. The Cabinet Noir, founded under Louvois, Frances Minister of War, at the urging of Antoine Rossignol, took extraordinary precautions by switching systems, introducing eighteen new nomenclator series. It was the start of Frances ironclad control over the cipher business. It still has a tight access policy today. The Vienna Black Chamber--the Geheime Kabinets--Kanzlei regularly read French ciphers up to the cabinet level.
Wallis
England had its Black Chamber. John Wallis who was Rossignol's contemporary, was first a mathematician, giving us the germ of the binomial theorem, the symbol and concept of infinity, a calculation of pi by interpolation and the beginnings of the calculus for Newton to do his thing with. John Wallis' solution of Louis XIV of France letter of 9 June 1693 put his name in the record books.
Wallis and Rossignol careers parallel each other. Both made their start on their countrys civil war ciphers in their twenties. Both had a mathematical bent. Both were self-taught. Both lived into their eighties. Both owed their worldly success to cryptanalysis. Both became their countries' Fathers of Cryptology in both the literal and figurative sense. But they were different too. Rossignol worked at court while Wallis worked at Oxford. Rossignol introduced new systems for the French and supervised their use. Wallis apparently prescribed only one English cipher and that was done informally.
It is unlikely that these cryptologic experts ever clashed cryptologically despite the contentious natures of both countries.
General Luigi Sacco
One of Italy's most brilliant cryptographers, he detailed solutions of various transposition, monoalphabetic and polyalphabetic systems. His appendix details the equations used for such interesting problems as de Viaris polyalphabetic substitution, Kerckhoff's' ciphers and the Hill algebraic problem.
Changing Directions
Cryptology has flourished in secrecy itself--some might say obscurity. The available classic literature is hard to collect.
Professional cryptographers in the military and diplomatic services hold their cards tight to the vest of materials cryptographic. As a result, freely available literature never fully reflected the state-of-the-art--a condition that is bending a little in modern day politics. The United States under its Freedom of Information Act (FOI) has released a generous amount of information to satiate the public media. This is especially true when dealing with World War II communications. Up until the 1990s and only after the political disintegration of the "Old Soviet Union" did we find that the Soviets were very adept in the cryptography business. The French, who have not learned to cooperate with anyone, including the French, have the most oppressive laws regarding cryptography import/export/use. The Internet is quickly dissipating their position. The Germans and English have unique "Secrets Acts" but are working with the International community to improve security and maintain privacy interests for their countries.
The intelligence services do not usually reveal even the names of their leading cryptographers. Some have become too famous to hide. General Sir Stewart Graham Menzies (1890-1968) chief of M.I.6, the British Secret Intelligence Service was only known as "C". He was in charge of nearly 8,000 Passport Control Officers as well as the cryptanalytic unit at Bletchley Park (BP). His counterpart was Ernst C. Fetterlein (d. 1944).
He was the head of the Russian cryptanalytic Bureau and served the Government Code and Cipher School (GC&C) of the British Foreign Office.
The government and specifically the military consider cryptography and cryptosystems in general as weapons for defense and attack. The International Traffic in Arms Regulations (ITAR) and most recently the Bureau of Export (BXA) under the aegis of the Commerce Department has rules governing the release of "strong" cryptography to foreign interests without a license, which requires sub Rosa approval from the NSA or NIST. The government has approved millions of dollars of research to improve cryptosystems. Kahn and Nichols detail many stories where the battle turned because a better cryptographic system was in place. All the major powers in the Second World War had success in solving enemy cryptographic systems.
On the other sides are two counter forces, the commercial interests that want to bring products to market quickly and effectively to compete with foreign products that are not restricted as in the US, and the privacy interests of civil rights groups. The politics in 1997-1998 are fierce to say the least. The Internet is dissolving all the territorial responses to the issues. Phillip Zimmerman became a modern folk hero when he released PGP to the public over the Internet. PGP is akin to a tinker toy set with the right ingredients for encipherment, key exchange, trust levels and popular appeal. Early versions of PGP found their way around the globe and became distributed well before some of the contractual arrangements could protect the authors intellectual property and to the chagrin of the US Government. But, the most recent PGP version includes key recovery, a definite concession to the US government whims.
Side by side with state cryptology in diplomatic and military services have stood the amateurs. Since 1929, the American Cryptogram Association (ACA) has been the leader in recreational cryptography. Their free courses have included students from every intelligence and military discipline, talented amateurs from educational halls, and commercial players from the computer and information industries. From the revelations of historic events by Etienne Bazeries (1846-1931) to the amusements of Wheatstone and Lord Playfair to the vision of Edgar Allen Poe, a talented cryptographer whos works affected literature and science, to drug-runners stopped by the U.S. Coast Guard with the help of Elizabeth F. Friedman (1892-1980), to the popular mythology around President Kennedy, who used a Playfair cipher to send a message to his base after he was shipwrecked when his PT109 was cut in half to President Eisenhower who used a clever cipher system based on golf words, to Bush who built up the HUMINT Intelligence services to a shining level only to have it gutted by President Clinton, to the love notes my ten year old Diana sends me by fax using the telephone code. Cryptology shows a rich tapestry interwoven with history. Cryptologys many personalities make its history a particular pleasurable field--and for me a passion as well as a vocation.
Commercial interests take cryptography as serious as government. The International Computer Security Association (ICSA) pioneered the consortium model for certification of cryptography based products. The Cryptography Products Consortium (CPC), was formed to encourage the use of cryptography as an enabling technology and to educate the user community on the benefits and proper application of cryptography. There are thirty-nine members in the US consortium and nine more in the European group. The CPC IPSEC subgroup includes the entire automotive and trucking industry and has set the cryptographic standards on VPN (virtual private networks) for the world. The Internet Service Providers Security Consortium (ISPSEC) is dedicated to implementing global measures to improve security on the Internet. The seventeen "backbone" businesses use cryptography to protect one billion dollars worth of business in 1997. The implementation of strong cryptography is prima facia to this effort.
The increased need for information security has given cryptology a hitherto unrecognized importance. Private commercial applications of cryptography have come to the forefront and lead to some exciting new technologies. In particular the asymmetric public keys first proposed by Whitfield Diffie and Martin Hellman in 1976 have revolutionized the commercial cryptography market. Computer programs that have not had adequate copyright protection now use cryptography to preclude theft or unauthorized use. E-mail and E-commerce both use cryptography to authenticate business relationships. The Auto Industry Group (AIG) in conjunction with ICSA set the global security standards for Virtual Private Networks (VPN) and IP security (IPSEC) for auto/truck dealerships and Tier I suppliers.
We no longer have Morse code. We have satellites and optical fiber networks. Our code books are kept in laptops not jumpsuits. "Breaks" or "cracks" are now made using cooperative computer horsepower with thousands of stations in situ. Exploring an entire keyspace has little excitement and even less practicality. Tactically such "hits" are high show, low probability, and low functionality considering the counter-interception capabilities, random number generation abilities, the useful key life cycles and sizes, and the array of defensive algorithms offered, modern cryptographic products are up to the challenge of practical viability.
Cryptology for the "public" raises contradictions, hysterical claims and conflict of interests between numerous scientists, public, privacy, legal, businesses, and government. Mutual cooperation has become the workable solution to many of the questions of the day--so that will be our tone for this book.
Wrap-Up
Cryptographys history, people and development are intricately woven into societys fabric. We will first look at the basic principles of cryptography, then show how security of the classic systems was improved through complexity and cleverness and then move into the mechanization of cryptosystems. We will end our classical look at cryptography with a study of data encryption algorithm (DEA) which evolved into the data encryption standard (DES). DES is still popular today even though official moves to replace it with an Advanced Encryption System (AES) is moving rapidly forward. DES marks the turning point from classical cryptography to modern and public key cryptosystems.
Chapter: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 9 | 10 |
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