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In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
The Zendian problem was an exercise in communication intelligence operations (mainly traffic analysis and cryptanalysis) devised by Lambros D. Callimahos as part of an advanced course, CA-400, that Callimahos taught to National Security Agency cryptanalysts starting in the 1950s.
The scenario involves 375 radio messages said to have been intercepted on December 23 by the US Army contingent of a United Nations force landed on the fictional island of Zendia in the Pacific Ocean.
A typical intercept looks like this:
XYR DE OWN 4235KCS 230620T USM-99/00091 9516 8123 0605 7932 8423 5095 8444 6831 JAAAJ EUEBD OETDN GXAWR SUTEU EIWEN YUENN ODEUH RROMM EELGE AEGID TESRR RASEB ENORS RNOMM EAYTU NEONT ESFRS NTCRO QCEET OCORE IITLP OHSRG SSELY TCCSV SOTIU GNTIV EVOMN TMPAA CIRCS ENREN OTSOI ENREI EKEIO PFRNT CDOGE NYFPE TESNI EACEA ISTEM SOFEA TROSE EQOAO OSCER HTTAA LUOUY LSAIE TSERR ESEPA PHVDN HNNTI IARTX LASLD URATT OPPLO AITMW OTIAS TNHIR DCOUT NMFCA SREEE USSDS DHOAH REEXI PROUT NTTHD JAAAJ EUEBD
For each message, the first line is provided by the intercept operator, giving call signs, frequency, time, and reference number. The rest of the message is a transcript of the Morse code transmission.
At the beginning of the intercepted message there is a header which consists of 8 four-digit groups. Initially, the meaning of the numeric header is not known; the meanings of various components of this header (such as a serial number assigned by the transmitting organization's message center) can be worked out through traffic analysis.
The rest of the message consists of "indicators" and ciphertext; the first group is evidently a "discriminant" indicating the cryptosystem used, and (depending on the cryptosystem) some or all of the second group may contain a message-specific keying element such as initial rotor settings. The first two groups are repeated at the end of the message, which allows correction of garbled indicators. The remaining characters are encrypted text. Since the transmissions always use complete groups, "nulls" may have been used to pad out the text.
Cryptosystems employed include transposition, dinome, and rotor-based ciphers and a one-part code. While these can be successfully tackled without use of a computer, solution is not easy. The practical exercise reinforces many basic principles, including ways to exploit having a collection of message traffic.
A certain amount of Plaintext inter-operator "chatter" is also provided, and may help with the analysis.
Headers and discriminants are also given for intercepts from the next three days; these may be used for traffic analysis and in determining daily operating procedures.
The Zendian problem has been declassified and is available either as part of Military Cryptanalytics[1] or as a book in itself.[2] Both were published as reprints by Aegean Park Press, Walnut Creek, CA, USA. There are a few small differences in the ciphertext between these sources, with neither being entirely error-free; indeed, some errors were intentional, and dealing with them is part of the learning process.
A February 1958 NSA-hosted scan of Military Cryptanalytics, Part II, Interim Edition (Third Section), containing the Zendian problem as Appendix 8, is freely available online.[3]
Karl Heinz-Everts' Web site provides a link to a downloadable archive[4] of the "intercepts." (The site also provides analysis and partial solutions, which should not be viewed by anyone wishing to learn from working on this exercise.)
Cryptanalists who successfully finished CA-400 became members of the Dundee Society. This society was founded by Lambros D. Callimahos[5] and was so named after the empty Dundee marmalade jar on his desk, as he couldn't disclose the society's real purpose.
A large print showing the fictional nation of Zendia hangs on the wall of the library at the National Cryptologic Museum, which is operated by the NSA. Copies of this map, shrunken to such a degree that most feature labels are illegible, appear in the previously cited books.
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The Zendian problem was an exercise in communication intelligence operations (mainly traffic analysis and cryptanalysis) devised by Lambros D. Callimahos as part of an advanced course, CA-400, that Callimahos taught to National Security Agency cryptanalysts starting in the 1950s.
The Dundee Society was a society of graduates of CA-400, a National Security Agency course in cryptology devised by Lambros D. Callimahos, which included the Zendian Problem (a practical exercise in traffic analysis and cryptanalysis). The class was held once a year, and new members were inducted into the Society upon completion of the class. The Society was founded in the mid-1950s and continued after Callimahos retired from the NSA in 1976. The last CA-400 class was held at NSA in 1979, formally closing the society's membership rolls. The society took its name from an empty jar of Dundee Marmalade that Callimahos kept on his desk for use as a pencil caddy. Callimahos came up with the society's name while trying to schedule a luncheon for former CA-400 students at the Ft. Meade Officers' Club. Being unable to use either the course name or the underlying government agency's name for security reasons, he spotted the ceramic Dundee jar and decided to use "The Dundee Society" as the cover name for the luncheon reservation. CA-400 students were presented with ceramic Dundee Marmalade jars at the close of the course as part of the induction ceremony into the Dundee Society. When Dundee switched from ceramic to glass jars, Callimahos would still present graduates with ceramic Dundee jars, but the jars were then collected back up for use in the next year's induction ceremony. Members were "encouraged" to seek out Dundee jars for their collections if they wished to have a permanent token of induction.
Cryptanalysis (from Greek kryptós 'hidden' and analýein 'to analyze') refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown. In addition to mathematical analysis of cryptographic algorithms, cryptanalysis includes the study of side-channel attacks that do not target weaknesses in the cryptographic algorithms themselves, but instead exploit weaknesses in their implementation. Even though the goal has been the same, the methods and techniques of cryptanalysis have changed drastically through the history of cryptography, adapting to increasing cryptographic complexity, ranging from the pen-and-paper methods of the past, through machines like the British Bombes and Colossus computers at Bletchley Park in World War II, to the mathematically advanced computerized schemes of the present. Methods for breaking modern cryptosystems often involve solving carefully constructed problems in pure mathematics, the best-known being integer factorization.
Fort George G. Meade is a United States Army installation located in Maryland, that includes the Defense Information School, the Defense Media Activity, the United States Army Field Band, and the headquarters of United States Cyber Command, the National Security Agency, the Defense Courier Service, Defense Information Systems Agency headquarters, and the U.S. Navy's Cryptologic Warfare Group Six. It is named for George G. Meade, a Union general from the American Civil War, who served as commander of the Army of the Potomac. The fort's smaller census-designated place includes support facilities such as schools, housing, and the offices of the Military Intelligence Civilian Excepted Career Program (MICECP).
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →The Greenwood District.
