20 Years of Cryptologic Challenges

This year will mark the 21st anniversary of our Enigma simulator and the 20th year of cryptologic challenges. It all started in early 2006 with the Enigma Challenge to decrypt ten messages. Although the challenge was a one-time event, the feedback encouraged us to continue the challenge. The original 2006 results are included in the all-time Table of Honor of the currently running challenge.

The Enigma machine,  Crypto Box and TSEC/KL-7 ADONIS

In the following years, we introduced four more challenges, each with its own Table of Honor that lists all participants. The crypto machine simulations in the Enigma Challenge and Operation Tinker Bell work exactly like the real machines, making for authentic experience.

Some challenge statistics (updated 20 April 2026)

Enigma Challenge (est. 2006)

Currently, 366 participants from 46 countries solved 2,471 messages. This challenge is quite accessible and no expert knowledge on cryptologic techniques is required. This challenge serves as an introduction to codebreaking. Most participants get quite far with logical thinking, patience and some perseverance, with 55% of them solving eight to ten messages. Visit in English or Nederlands.

Crypto Box Challenge (est. 2007)

This transposition cipher is more difficult and 89 participants from 26 countries submitted 162 solutions. The first Crypto Box is not that difficult, but complexity increases rapidly. To this day, only 13% solved the three boxes and 87% solved one or two boxes, which is quite meritorious, given the difficulty level. Some cryptanalytic knowledge is useful but hard work also pays off. Visit in English or Nederlands.

Operation Tinker Bell (est. 2013)

This is an accessible cryptologic spy adventure set in an authentic Cold War atmosphere, focusing on secure communications between intelligence agencies and their agents and operatives in the field. No cryptologic skills are required. All authentic crypto tools, keys, and instructions are provided to solve the case. Those who complete the mission have their names engraved on the Wall of Honor. Currently, the operation has been completed by 33 participants who deciphered a total of 1,716 messages. Visit only in English. 

Elite Box Challenge (est. 2022)

The Elite Box is the Crypto Box on steroids. To this day, only one person managed to solve two out of the three boxes, and four participants solved one box. The first box already starts with a higher number of steps, there's one box with an unknown number of steps, and one box has an unknown type of fractionated characters, requiring more than simply shifting rows and columns. Cryptanalytic techniques are required to solve this one. Visit in English or Nederlands.

The Crow's Cryptogram (est. 2010)

Although already published in 2010, there's a good reason why the Crow's Cryptogram is the last one on our statistics list. Only encrypted with a pencil-and-paper system, this one comes with a single hint, and has 600 digits in 120 five-digit groups. The bleak statistics: only one person ever solved this cryptogram. Expertise in cryptanalytic techniques is required. Visit in English or Nederlands.

If you're in for a cryptologic adventure, enjoy the challenges!

Cipher Machines and Cryptology Moved!

Our website Cipher Machines and cryptology moved to a new location with new domain name! Visit the website at www.ciphermachinesandcryptology.com.

Despite the odd users-page URL, the old website still managed to attract 4.374.600 visits from across the world. I never expected this for an "obscure" subject as cryptography, hence the simple users storage server. The provider however recently decided to terminate the users web spaces, and we had to find another server and domain, but that's all past history now.

The new website has its own dedicated place on the www, but there's more. The website now supports https, making your visit secure and anonymous, as your connection is encrypted. Quite normal today, but https wasn't that common for non-commercial websites in 2004.

 

Finally moved to www.ciphermachinesandcryptology.com

The move also involved adjusting numerous links. The website runs smoothly, but given the many changed internal links, you might need a hard refresh of the moody webpage to clear obsolete links. And if you ever lose our address, simply remember the good old Cipher Machines and Cryptology, with dot com... or simply visit this blog again ;-]

If you saved the old link in your bookmarkes or favorites, or published the link on a webpage or blog, make sure to change the old URL into the new www.ciphermachinesandcryptology.com. Much appreciated, as it can take weeks or even months before Google indexes a moved website completely, despite registering in their Search Console. Spread the news of the move!

If you ever wondered what a domain name actually is, and who is running the DNS or Domain Name System, then check this video from The Guardian. Well, thank you guys for keeping my new domain name safe. See also this post from The Guardian.

Who holds the seven keys to the internet?

The Atomic Age - Black on White

Following up on my Camp Century post about the use of a small nuclear power reactor in Greenland, I would like to recommend two fascinating websites about atomic energy and nuclear weapons.

Mark's weblog Atomic Skies covers a wide range of applications of atomic energy. He presents both technical and historical facts, based on publicly available papers. Some of the installations, devices and ideas, conceived in the early years of atomic energy, were pretty amazing. This mysterious energy inside that tiny atom produced both some of the weirdest and some of the most brilliant inventions, from nuclear air planes to today's pretty secure nuclear reactors.

Alex Wellerstein is an historian of science at the American Institute of Physics. Alex is the author of the Nuclear Secrecy Blog and historical documents are his natural biotope. His work covers the complete nuclear era but focuses mainly on the development of the atom bomb during WW2 and the early Cold War years. He explains in an excellent way the military, technical, as well as the historical aspects of the bomb and the men who developed it.

Together, Atomic Skies and  Nuclear Secrecy Blog are good for countless hours of fascinating reading. Highly recommended

BREAK THE CODE!

A new codebreaking contest, called BREAK THE CODE!, is now on-line. The challenge is organised by the Polish state institutes Wielkopolska Region and the Office for War Veterans. The game starts on December 10, 2011, but the 3-person teams can already register to take part at this challenge.

The challenge is created to commemorate the Polish achievements in breaking the German Enigma cipher machine prior to the Second World War. The two best teams will play the finals in Poland. The trip is part of the prize, apart from electronic equipment. Only European citizens (Poland excluded) can compete for the prizes. Non-Europeans are also invited to enter the contest and will be included in the over-all game classification.

The information about how the game works and how to register is already available on the website. For each stage in the contest, a lecture, related to cryptography, will be published on the website. The first lecture, to make the teams familiar with codebreaking and the contest, is already available from the game control panel. For more information on this great initiative, please visit their website codebreakers.eu.

If you think you're up to the job, don't hesitate! Put together a team of three and register before December, 10, when the challenge starts.

Christos Military and Intelligence Corner

Christos military and intelligence corner

There are not too many websites or blogs about Signals Intelligence during the Second World War, especially not the kind that focuses on specific parts of the war over radio waves. Last July, Christos started a new blog that mainly covers the German intelligence efforts. He already provided some most interesting information about the German interception and cryptanalysis of enemy codes and ciphers.

There's little known about  the German work on SIGINT (Signals Intelligence) because much of this information, and many of the German military who worked in that field, were picked up at the end of the war. The British-American TICOM project  (Target Intelligence Committee) was especially focused on gathering important cryptologic information, and to prevent it from falling into the hands of the Soviets. Unfortunately for historians, they did a good job in hiding that information from the public, but more and more information is gradually released into the public.

Christos' weblog articles fill up a gap in the blogosphere and I hope he keeps on writing and providing valuable links to documents and web pages on German cryptologic work during WW2. It is important that the story of the war is based on information of both sides, and the German intelligence work and cryptologic successes should receive their place in that history. We now know that, although the implementation of German cryptologic systems was often weak, they did develop magnificent crypto equipment, had some fine cryptologists and excelled in the field of radio technology and interception.

Do visit Christos's Military and Intelligence Corner to discover that other view on WW2 Signals Intelligence.

If you're interested in German SIGINT, you might start off by reading European Axis Signal Intelligence in World War II, published last year by NSA on their Declassification and Transparency project. These documents give an excellent view on the organisational structure and results of Germany's wartime intelligence.

German signals intelligence has always been underestimated or portrayed as inferior. This was not only the case during WW2 but also during the Cold War. The misconception that East German intelligence relied mostly on Human Intelligence was an expensive one, as you can read on my blog about Stasi SIGINT operations.

Peace Ambassador in the Cold War

Samantha Smith

The story of Samantha Reed Smith is both amazing and tragic. She became a symbol of hope and friendship during the Cold War era and she managed to obtain an answer about the nuclear threat, straight from her source inside the Kremlin.

At the time, few realised that what she learned from her source were the real Soviet strategic intentions, recently backed by declassified interviews with Soviet policy makers and high ranked Soviet military. An achievement even the CIA could not match. The amazing thing about her is that she was only 10 years old and her source was none other than Soviet leader Yuri Andropov.

Letter to the Soviet Leader

The early 1980's brought a new rise in tensions between the Soviet Union and the United States. After years of so-called détente, a new build-up of strategic nuclear weapons started in both East and West. In November 1982, ten year old American Samantha Smith took the bold decision to write a letter to the newly appointed Soviet leader Yuri Andropov. Driven by the fear for a global war, she wanted to ask him whether he had peaceful intentions or that he wanted war, as some media wrote. Here's her actual letter to the Soviet Leader:

"Dear Mr. Andropov,

My name is Samantha Smith. I am ten years old. Congratulations on your new job. I have been worrying about Russia and the United States getting into a nuclear war. Are you going to vote to have a war or not? If you aren't please tell me how you are going to help to not have a war. This question you do not have to answer, but I would like to know why you want to conquer the world or at least our country. God made the world for us to live together in peace and not to fight.

Sincerely,

Samantha Smith "

The Soviet newspaper Pravda published her letter but she did not receive any reply. Therefore, she wrote to Soviet Ambassador to the United States Anatoly Dobrynin, asking him whether Andropov would answer or not, and he did!

Samantha with Andropov's letter

On April 26, 1983, she received a response from President Yuri Andropov himself, and he explained her that the people of the Soviet Union wanted to live in peace and would never ever be the first to use nuclear weapons or start a new World War.

He also invited her to visit the USSR, meet children of her own age and visit an international children's camp. She attracted massive media attention in the USSR and the US, and she became known as America's youngest ambassador.

Touring in Russia

Samantha at the Artek Pioneer camp

On July 7, 1983, Samantha flew to Moscow with her parents. During the two week trip, she visited Moscow, Leningrad and the Artek Young Pioneer camp on the Black Sea. She was struck by the friendliness of the people and told on a Moscow press conference that the Russians were "just like us".

Five months later, she visited Japan as child goodwill ambassador. Others followed in her footsteps, including eleven year old Katya Lycheva from the Soviet Union, who visited the United States. Samantha also became a media celebrity, hosted a special on Disney Channel, wrote the book "Journey to the Soviet Union", interviewed politicians and co-starred with Robert Wagner in the television series "Lime Street".

Her innocently naive, yet noble initiative resulted in a written statement from Soviet leader Andropov that the Soviet Union would never start a nuclear war. It might sound naive but, as the records have shown, he told the truth. Her noble intentions to bring people together should be an example to all of us, never to be forgotten.

Two years later, on August 25, 1985, tragedy struck when Samantha Smith and her father died in a plane crash. Their small Beechcraft 99 crashed just before landing, killing all six passengers and two crew on board.

Samantha's Legacy as Symbol of Hope

Commemorative stamp

She was mourned by millions of people at home and in the Soviet Union. Vladimir Kulagin from the Soviet Embassy, who attended the funeral, read a personal message of condolence from Mikhail Gorbachev, and President Reagan sent his condolences in writing to her mother.

The Soviet Union issued a commemorative stamp, built a monument in Moscow and even named an asteroid to her. Manchester, her hometown in Main, honored her with a statue and the first Monday in June of each year is officially named "Samantha Smith Day" in Maine. In 1985, Samantha's mother also founded the Samantha Smith Foundation, which fostered student exchanges between the US and USSR.

"When Samantha Smith was killed in a plane crash, millions of people all over the world grieved as if for their own child. For, in a way, she was a child of the world - a symbol of childhood itself, a guardian of our dreams and hopes for children everywhere" (from Citizen Diplomats: Pathfinders in Soviet American Relations)

The Samantha Smith website brings the story of this little girl that, in her own way, brought East and West a bit closer and sparked a glimmer of hope, something many diplomats and politicians could not achieve back then. On her website you find Andropov's letter, read about the foundation, view many images (use "next page" at the bottom of each page) and visit her Youtube channel with videos about her visit to the USSR and interviews. The U.S. Embassy in Russia also had a tribute page on Samantha.

Update: New podcast about Samantha Smith, including interview with childhood friends, her Russian buddy during het tour in the Soviet Union and actor Robert Wagner with whom she played in the TV series Lime Street.

Below the 60 Minutes special by WGAN/CBS, aired on July 27, 1983. From the SamanthaSmithInfo Youtube channel.

To Russia With Love

Enigma Patents

Enigma Rotor in Patent

The Crypto Museum website has published a large number of original patents, related to the German Enigma cipher machine. These documents, dated from 1918 to 1923, show the development of the Enigma machine and contains a large number of detailed technical drawings. Electrical circuits, different types of ciphering wheels and various mechanisms to advance them, printing systems and much more.

Some of the patents were filed by German engineer Arthur Scherbius, others by firms such as Gewerkschaft Securitas of Berlin and Chiffriermaschinen AG, both related to Scherbius. However, similar patents were filed by firms in the United States, the Netherlands, France and the United Kingdom, some of them related to Germany based companies.

All patents are available in pdf format on Paul Reuvers' and Marc Simons' Crypto Museum Enigma patents page. More patents are found on Arthur Bauer's Foundation for German Communication.

Crypto Museum

Paul Reuvers and Marc Simons finally found the time to merge all their wonderful information and photos of cipher machines into a beautiful website.

The Crypto Museum website is a refreshingly new site with lots of information on many cipher machines such as the well known German Enigma, various Hagelins, the Swiss Nema, the American M-209, KL-7 and SIGABA, but also less known machines. The Swedish Transvertex, the Gretacoder, several crypto devices from Philips, Siemens and many many more.

You can view hundreds of superb and very detailed photos they took of these marvels. But there's more! They also collected information and took photos of spy radio sets, burst encoders and several direction finders. Some of these are true Cold War jewels. The site is still under construction, although the collection is quite impressive already. A Kits section, News section and a Shop are in the pipe-line. Paul and Marc are by the way the developers of the Enigma E, the electronic kit that works exactly like the real thing.

Good information on old crypto machines is rare, and good websites on these machines are hardly available (Jerry Proc is one of the few). The Crypto Museum website is therefore a unique initiative with an unmatched collection of high quality images. A true delight of the senses, molded into a well designed and synoptic website. I can only urge you to visit the Crypto Museum website. A must!

Their Crypto Index page, lists all available crypto equipment, but as I mentioned before, there's much more to discover. Now, go... go!

Paper Enigma Replika

Unless you're living on another planet, you probably have noticed there's a financial crisis. I can imagine that many people are dreaming of their own Enigma machine, but currently have more useful things to do with their money. The unfortunate among us could try out my freeware Enigma simulator, which looks and works like the real thing or Mike Koss' Paper Enigma. However, now there's also a paper Enigma that looks exactly like the real thing!

You can construct your own Enigma machine with only a color printer, scissors and a bit of glue. Go to the Paper Replika website download the pdf Enigma M4 Naval machine, print it out in color and put it together. That's it! You don't need stiff card paper, plain paper will do just fine. This is the perfect solution for those who always wanted an Enigma machine on their desk without paying their pants off.

It's very beautiful, with realistic colors and nice details like an opening lid, plugs, rotors that stick out, and even the typical M4 handles. With some patience and a sharp cutter, you'll be able to make a real beauty. If you donate $2.00 you can obtain a larger version without the website credits on the machine.

Siemens Hell-Feldfernschreiber

The german Hellschreiber

A most ingenious way to relay text from one point to another is the Hellschreiber, developed by Rudolf Hell in the 1920's. The Hellschreiber enables readable and error-free communication, even under poor conditions, over radio or land-lines.

Text characters are composed by a 7 x 14 matrix and sent as a serialized audio signal to the receiver. The Hell receiver prints out the characters on paper with a unique double winded spindle. It's a simple yet robust system that enables a speed of 150 characters per minute.

The ingenious of the Hell design is how it visually handles error correction and synchronisation problems. The special spindle prints the text twice on the paper ribbon in order to make it readable in all conditions, even when sender and receiver are not fully synchronised.

The Hellschreiber went into service in 1934 and its speed and reliability made it very popular with press agencies and very suitable for diplomatic and military communications. The German Wehrmacht, Luftwaffe and Kriegsmarine used the system from 1935 until 1945 for field operations.

Although this beautiful machine has become obsolete due to the introduction of Telex, Fax and e-mail, the device, and software versions of it, remains popular with radio amateurs. Frank Dörenberg created an excellent Hellschreiber page (Internet Archive version). He composed a detailed historical and technical description of the Hellschreiber. Make sure to visit the 'How it Works' section with its beautiful animated images that demonstrate perfectly how the machine works.

HASH THAT!

For all newbies in the world of cryptography or anyone who is wondering what cryptography can do for us, there's an interesting project called HashThat!, created by students and for students. It's a very beautiful and clear introduction in cryptography and a fun page to read and discover.

The Fundamentals section explains what crypto means, the crypto vocabulary, and the basics of cryptography. In the Down The Ages section you can learn about the history of cryptography through the ages and get familiar with some of the most famous cipher machines.

After reading the Relevance Today page you will understand how important crypto is to us in all day life. The Lighter Side and Interact sections are fun to read, listen and play, and there are interesting audio interviews with Phil Zimmermann and crypto history icon David Kahn. Make sure to explore the menus at the right of each page!

I can recommend a visit to the HashThat! website. Look and learn!

Site Review: Elonka Dunin

Elonka Dunn

Elonka Dunin is an American writer, cryptographer and game developer. She's a busy lady and was even invited to speak at FBI and NSA meetings and CIA headquarters about steganography and Al-Qaeda codes. 

In 2003, she organized a team that cracked the Cyrillic Projector, a sculpture by James Sanborn, containing an encrypted text. Another work of Sanborn is the Kryptos sculpture on the grounds of the CIA in Langley. Elonka co-founded the Kryptos Group about the breaking of Kryptos.

On her website you can find a most interesting page on the efforts on breaking Kryptos and her famous list of unsolved codes and ciphers. Still plenty of ciphers to be solved, so if you have the time, go ahead. She also published The Mammoth Book of Secret Code Puzzles. You can also find the transcript of the cracked Cyrillic Projector code on her site. If you're interested in cryptology and other mysterious stuff, I can recommend her weblog on memestreams.net.

Foundation for German Communication

The Foundation for German Communication and related Technology is a foundation that preserves the history of German technology, more in particular from before and during the Second World War.

It's a huge collection of original documents, plans and circuit diagrams about all sorts of technology, ranging from radio equipment, encryption devices, patents, measurements, radar and company history.

I was especially pleased to find detailed documents and images about the G-Schreiber T52d cipher machine, the Kurier system, which is a German type of burst encoder transmission system, and radio equipment from the Abwehr (German secret service). There's an extensive Handbooks section with a wealth of original documents. Don't forget to visit the Archive displays with lots of detailed images of all kinds of equipment.

The diversity on documents and artefacts is far too large to explain here.Visit the Foundation for German Communication website to discover it yourself !

NSArchive on SpyCast

I already wrote a site review on the National Security Archive last December. This month, Peter Earnest from the International Spy Museum interviewed Tom Blanton of the National Security Archive.

They talk about recently declassified documents about CIA activities in the Cold War, the assassination attempts at Fidel Castro and domestic wiretapping. Another interesting interview in the Spycast series.

you can listen to From the Secret Files of the CIA with Tom Blanton. More podcasts available at the SpyMuseum's Spycast.

Site Review: Computer History

While reading this blog in a wealth of fine colors on your 2 GHz computer with 1,000 Mb of memory and 300 Gigabyte hard disk you might wanna surf with your wireless optical mouse to the Computer History Museum.

The site contains lots of information on the development of computers. There's an interesting timeline where you find descriptions and photographs of computers, from the first models, operating with enormous banks of relays, to the latest technology. But there's more! You can search by category, read about companies, computer components, languages, games and the development of network communication. 

There's an on-line exhibition tour that covers the history of the groundbreaking PDP-1 and the museum’s recent restoration of a PDP-1 to working order. In the visible storage you find a wealth of photographs. Another great site is old-computers.com. This site has an enormous archive with nearly all computers, including their technical details.

You can browse through the archive by name, year or company. There's a nice history section, describing in detail the development of computers. Surfing through these pages I can't help feeling a bit nostalgic. Writing software for over 25 years myself, I remember the days of hex code programming, simple compilers and the art of squeezing programs into a 64 Kilobyte memory. It's been a quantum leap from the first computers to your high-tech laptop. But one thing never changed: it's all about 0 and 1.

SpyCast

International Spy Museum

Since recently the International Spy Museum offers a SpyCast. These podcasts are interviews with ex-spies, intelligence experts and espionage scholars, that you can download and play on your PC or MP3 player. The SpyCast is hosted by Peter Earnest, a former CIA operations officer, and gives you the change to hear intelligence stories right from the key players themselves.

I just listened to some interesting interviews, or SpyCasts as they are called. The first one was with Oleg Kalugin, former Major General of the Soviet KGB and now living in the US. He discusses the espionage conflict between Russia and Georgia about the four GRU officers, and he goes back into time to talk about the Cuban Missile Crisis in 1962. In the second interview with former CIA officer Bob Rayle and KGB General Oleg Kalugin they discuss on the poisoning of former KGB spy Alexander Litvinenko. Bob Rayle also tells the story on the extraordinary defection of Svetlana Alliluyeva, daughter of Josef Stalin, and how he escorted her out of India to flee the USSR.

These and more interviews or programs are available for download at the International Spy Museum Spycast page, or the SpyCast feed on FM Player. I can recommend a visit to the Spy Museum site with lots of inside information from the past, or you can even visit the museum which is located in Washington DC.

Site Review: National Security Archive

Visit the National Security Archive

Top secret projects, Intelligence Agencies or high level diplomatic arm wrestling are most appealing topics and we all have our opinion on what the spooks are doing behind our backs or try to find a more or less paranoia top secret government project behind a UFO spotting. One way to understand things that happen today is to look at the past, which can be found in the archives.

Although reading government archives will bring you only their side of the story it can help you to form your own idea of what happened. Unfortunately, too few people take the effort to dig their nose into the wealth of archives that are collecting dust. A great source is the National Security Archive from the George Washington University. Although you won't find here secret stuff about G.W. Bush or Rumsfeld you can read about the past, how things were handled back then, and project this to the present.

In the Documents Section you find the nuclear history, the Cuban missile crisis, nuclear first strike options, Vietnam, Latin America, government secrecy. Enough to keep you reading for months. You think you got the right to know something? The Freedom of Information Act (FOIA) is a federal law that establishes the public's right to obtain information from federal government agencies. In the News Section you can read the newest archive entries.

Site Review: Toby's Cryptopage

Torbjörn Andersson from Sweden has interesting information on cryptology at his website Toby's Cryptopage (archived). There's basic cryptography and cryptanalysis and some Swedish cipher codes. He also composed a great chapter on the Swedish cryptographer Boris Hagelin and his successful cryptomachines, which incudes some nice images.

A most interesting part is his From The Archives section (archived). Some years ago he was granted access to the archives of the Swedish signal intelligence organization FRA, Forsvarets Radioanstalt or National Defence Radio Establishment.

There are several interesting Second World War cipher codes presented from the Soviet Forces and also a few German codes. Amongst the Russian codes are Cheka and OGPU stations cipher keys, a few tank codes, Baltic Navy codes and NKVD codes. There's also a description of the Call sign encryption system of Soviet ground forces in WW2. Most interesting!

Site Review - Jerry Proc

Jerry Proc

Over the years, Jerry Proc created a wonderful on-line crypto collection. His site, called Crypto Machines, contains a large number of images and background information on numerous cipher machines.

It's a very complete collection, giving us a good view on the development of these machines, during the last century. From the Confederate Cipher Disk, Russia's Fialka, the Hagelin models, over WW2 machines such as the German Enigma and Sturgeon, or the American SIGABA, KL7 to the more recent electronic devices like STU III, SINCGARS or KG-235 Sectera Network encryptor. The KG, KY, BID and KW series. You name it, it's on his site.

Although Jerry claims not to be a crypto expert, his passion makes the website Crypto Machines a reference to cryptographic devices from across the world.

Site Review - John Savard

Some people seem to have lots of free time, or work hard, and like to share what they did with it. Those who don't swimm in free time and are interested in mathematics, computer or cryptology should visit John Savard's website. His Cryptographic Compendium.section has extensive information on classical cryptography, crypto machines and computer crypto algorithms. As a cryptomaniac, that's candy to me.

However, there's more.Visit John Savard's Quadibloc website and scroll on that page.to find a huge list of topis. If questions about computers and how they work, take a peek in his Computer sections, and his Mathematics pages are also worth a visit. Other subject are telescopes, optics, chess, large numbers, signal flags, etc etc. ..

This site reminds me at Greg Goebel's amazing Vector Site with his great DayVectors webblog on many different scientific topics. Also a must-see! I wich I had the time to creat such amoungts of information.