Cryptography Uses Photon Streams

The quirky world of quantum physics, where mathematical elements can hold multiple values and objects can be in several places at once, is heading toward commercial products.

A start-up company, MagiQ Technologies, plans to announce today a cryptogaphy — or code — system that uses a technology called quantum key distribution to thwart eavesdropping on a fiber optic communication channel. The company, based in New York, says it has a working model of its system and will have a commercial version available in the second half of next year.

With the system, keys to the code are transmitted as a stream of photons, sent over a fiber optic cable. Because of the properties of quantum physics, the mere act of observing the transmission would alter the photons, rendering their information useless to any eavesdroppers.

A limit of the system is that it would not work on the Internet, only over dedicated fiber cables in which the photon transmission can be carefully controlled. But outside researchers say that quantum cryptography does make possible electronic conversations that would be immune to eavesdropping.

”MagiQ seems to be ahead of the research community in terms of making this affordable and practical,” said Dr. Burton S. Kaliski Jr., the chief scientist of RSA Laboratories, one of the leading developers of conventional cryptographic systems.

Research in quantum cryptography goes back into the 1980’s. But MagiQ (pronounced as magic) and a Swiss competitor, ID Quantique, are the first to attempt to develop commercial systems based on the technology. ID Quantique’s system has not yet reached the market.

MagiQ was founded in 1999 by Robert Gelfond, a former securities trading executive for D. E. Shaw & Company who was also a first-round investor in Amazon.

The company has raised $6.9 million from investors who include Amazon’s founder, Jeff Bezos; Walter Riley, the chairman of Guaranteed Overnight Delivery; and Neal Goldman, the president of Goldman Capital Management.

Industry analysts say that military applications would probably be the primary use for quantum cryptography. ”The Defense Department is going to care, and that’s big money for a small start-up to survive on,” said Laura Koetzle, a computer security analyst at Forrester Research.

MagiQ also plans to explore other commercial applications from quantum physics, including quantum computing. Some scientists predict that computers based on quantum principle are possible and will be able to perform specialized tasks far more quickly than computers can.

Chart: ”Turning Photons Into Computer Code” A photon the quantum unit of light can be oriented in one of four possible positions. These positions, called the photon’s polarization, can be used to convey information, much like a string of 1’s and 0’s in computer code. HOW IT WORKS The polarizations can be vertical, horizontal or diagonal. Two of the polarizations are designated as 1’s and the others as 0’s. Photon detectors try to read photons either in a horizontal or vertical polarization or in a diagonal polarization. If the detectors choose the right orientation, they are able to read the number.


Basic Concepts & History of Cryptography

* The oldest means of sending secret messages is to simply conceal them by one trick or another. The ancient Greek historian Herodotus wrote that when the Persian Emperor Xerxes moved to attack Greece in 480 BC, the Greeks were warned by an Greek named Demaratus who was living in exile in Persia. In those days, wooden tablets covered with wax were used for writing. Demaratus wrote a message on the wooden tablet itself and then covered it with wax, allowing the vital information to be smuggled out of the country.


The science of sending concealed messages is known as “steganography”, Greek for “concealed writing”. Steganography has a long history, leading to inventions such as invisible ink and “microdots”, or highly miniaturized microfilm images that could be hidden almost anywhere. Microdots are a common feature in old spy movies and TV shows. However, steganography is not very secure by itself. If someone finds the hidden message, all its secrets are revealed. That led to the idea of manipulating the message so that it could not be read even if it were intercepted, and the result was “cryptography”, Greek for “hidden writing”.


Cryptography takes two forms: “codes” and “ciphers”. The distinction between codes and ciphers is commonly misunderstood. A “code” is essentially a secret language invented to conceal the meaning of a message. The simplest form of a code is the “jargon code”, in which a particular arbitrary phrase, for an arbitrary example:


 The nightingale sings at dawn. 

— corresponds to a particular predefined message that may not, in fact shouldn’t have, anything to do with the jargon code phrase. The actual meaning of this might be:

   The supply drop will take place at 0100 hours tomorrow.

Jargon codes have been used for a long time, most significantly in World War II, when they were used to send commands over broadcast radio to resistance fighters. However, from a cryptographic point of view they’re not very interesting. A proper code would run something like this:


This uses “codewords” to report that a friendly military force codenamed BOXER SEVEN is now hunting an enemy force codenamed TIGER5 at a location codenamed RED CORAL. This particular code is weak in that the “SEEK” and “AT” words provide information to a codebreaker on the structure of the message. In practice, traditional military codes are often defined using “codenumbers” instead of codewords, listed in a codebook that provides a dictionary of code numbers and their equivalent words. For example, this message might be coded as:

   85772 24799 10090 59980 12487

Codewords and codenumbers are referred to collectively as “codegroups”. The words they represent are referred to as “plaintext” or, more infrequently, “cleartext”, “plaincode”, “placode”, or “plaindata”.

Codes are unsurprisingly defined by “codebooks”, which are dictionaries of codegroups listed with their corresponding their plaintext. Codes originally had the codegroups in the same order as their plaintext. For example, in a code based on codenumbers, a word starting with “a” would have a low-value codenumber, while one starting with “z” would have a high-value codenumber. This meant that the same codebook could be used to “encode” a plaintext message into a coded message or “codetext“, and “decode” a codetext back into plaintext message.


However, such “one-part” codes had a certain predictability that made it easier for outsiders to figure out the pattern and “crack” or “break” the message, revealing its secrets. In order to make life more difficult for codebreakers, codemakers then designed codes where there was no predictable relationship between the order of the codegroups and the order of the matching plaintext. This meant that two codebooks were required, one to look up plaintext to find codegroups for encoding, the other to look up codegroups to find plaintext for decoding. This was in much the same way that a student of a foreign language, say French, needs an English-French and a French-English dictionary to translate back and forth between the two languages. Such “two-part” codes required more effort to implement and use, but they were harder to crack.


* In contrast to a code, a “cipher” conceals a plaintext message by replacing or scrambling its letters. This process is known as “enciphering” and results in a “ciphertext” message. Converting a ciphertext message back to a plaintext message is known as “deciphering”. Coded messages are often enciphered to improve their security, a process known as “superencipherment”.


There are two classes of ciphers. A “substitution cipher” changes the letters in a message to another set of letters, or “cipher alphabet”, while a “transposition cipher” shuffles the letters around. In some usages, the term “cipher” always means “substitution cipher”, while “transpositions” are not referred to as ciphers at all. In this document, the term “cipher” will mean both substitution ciphers and transposition ciphers. It is useful to refer to them together, since the two approaches are often combined in the same cipher scheme. However, transposition ciphers will be referred to in specific as “transpositions” for simplicity.


“Encryption” covers both encoding and enciphering, while “decryption” covers both decoding and deciphering. This also implies the term “cryptotext” to cover both codetext and ciphertext, though the term “encicode” is sometimes seen instead. The science of creating codes and ciphers is known, as mentioned, as “cryptography”, while the science of breaking them is known as “cryptanalysis”. Together, the two fields make up the science of “cryptology”.




An international team of computer scientists has cracked a manuscript detailing rituals of an 18th-century German secret society.


The text, known as the Copiale Cipher, is a 105-page book that was written in a combination of elaborate symbols and Roman letters. Previous attempts to decode it had failed, and it was clear that the cipher being used was more sophisticated than most. It is located in the former East Germany and was signed by a “Philipp” in 1866.


Kevin Knight, a computer scientist at the Information Sciences Institute at the University of Southern California, collaborated with two colleagues, Beáta Megyesi and Christiane Schaefer of Uppsala University in Sweden. They found that the text was in a sophisticated substitution cipher, which means that the letters one would expect were replaced with symbols.

Such ciphers are common in children’s games –- you might remember the “pigpen cipher” or shifting letters (making an “A” into a “C,” a “B” into a “D” and so on) from grade school. The Copiale manuscript was a step above that. Knight and his team originally thought –- as had many others –- that the visible Roman letters in the text were the coded message. But when they tried replacing those letters with others, all they got was nonsense.

That meant the symbols, or at least some of them, had to be what they were looking for. They tried the same thing on the unknown symbols. Again, they got nonsense, but the nonsense seemed to point to German as the original language.

Knight and his team assumed they were starting with German, as the book is from Germany and “Philipp” is a German spelling. They then looked at the frequency of different symbols and where they occurred together. This technique is centuries old and depends on the fact that different languages have combinations of letters that are allowed (or not). For example, in English, “q” is followed by a “u” in all but a few very rare words (and those are all foreign borrowings). That gave the linguists a few letters, which in turn allowed them to pick out more. Eventually they were able to transcribe the whole text.

The team has only translated the first 16 pages, but what the Copiale cipher revealed was a set of rules and initiation rites for a secret society. Such societies were more common in the 18th and 19th centuries, both as political and social organizations. (Yale’s Skull and Bones society was one of these).

The technique used in the Copiale manuscript, however, has more serious uses than plumbing the secrets of a clandestine society that has long since disbanded. Knight notes that many of his algorithms can be used in machine translation (and often are) and can be applied to other unknown texts and languages

Knight also said he has been very interested in one of the most famous coded texts: the Voynich manuscript, which has also stumped cryptographers and linguists for nearly a century. The Voynich is similar to the Copiale in that it is clearly in a coded text, but nobody is sure what the original language was or about the nature of the cipher.
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Fast Ride through Cryptography

Cryptography was used extensively during World War II, with a plethora of code and cipher systems fielded by the nations involved. In addition, the theoretical and practical aspects of cryptanalysis, or codebreaking, was much advanced.

Probably the most important cryptographic event of the war was the successful decryption by the Allies of the German “Enigma” Cipher. The first complete break into Enigma was accomplished by Poland around 1932; the techniques and insights used were passed to the French and British Allies just before the outbreak of the War in 1939. They were substantially improved by British efforts at the Bletchley Park research station during the War. Decryption of the Enigma Cipher allowed the Allies to read important parts of German radio traffic on important networks and was an invaluable source of military intelligence throughout the War. Intelligence from this source (and other high level sources, including the Fish cyphers) was eventually called Ultra.

A similar break into an important Japanese cypher (PURPLE) by the US Army Signals Intelligence Service started before the US entered the War. Product from this source was called MAGIC. It was the highest security Japanese diplomatic cypher.

Note worthy points back in history of code & ciphers :

Enigma : An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I.

Bergofsky ‘s Principle : the idea that if a computer tried enough keys, it is mathematically guaranteed to find the “right” one.

Bigglemans Safe: a hypothetical crypotgraphy scenerio in which a safe builder wrote blueprints for an unbreakable safe. He wanted to keep the blueprints a secret, so he built the safe and locked the blueprints inside.

ENIGMA: Continue reading