science

Kryha

Kryha is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Kryha rather than just read about it. In short: In the history of cryptography, the Kryha machine was a device for encryption and decryption, appearing in the early 1920s and used until the 1950s. The machine was the invention of Alexander von Kryha (born 31.10.1891 in Charkow, Russian Empire, committed suicide in Baden-Baden in 1955).

Key takeaways

Kryha belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kryha to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kryha from memory before moving on to harder problems.

Reference excerpt

In the history of cryptography, the Kryha machine was a device for encryption and decryption, appearing in the early 1920s and used until the 1950s. The machine was the invention of Alexander von Kryha (born 31.10.1891 in Charkow, Russian Empire, committed suicide in Baden-Baden in 1955). During the Second World War, Kryha worked as an officer for the German Wehrmacht. There were several versions; the standard Kryha machine weighed around five kilograms, and was totally mechanical. A scaled down pocket version was introduced later on, termed the "Lilliput" model. There was also a more bulky electrical version. The machine was used for a time by the German Diplomatic Corps, and was adopted by Marconi in England.

Operation

The machine consisted of two concentric rings each containing an alphabet. The inner alphabet was stepped a variable number of places by pushing a lever. In operation, the user would encrypt by finding the plaintext letter on one ring (usually the outer ring), and reading the corresponding letter on the other ring; this was then used as the ciphertext letter. When the lever was pressed, the inner ring would step, causing the relationship between the two alphabets to change. The stepping was irregular and governed by the use of a disk with a number of sectors, each containing a number of teeth.

Cryptanalysis

The security of the machine was evaluated by the mathematician Georg Hamel, who calculated the size of the key space. The US Army was also contacted to see if they would be interested in using the machine, and were persuaded to accept a challenge message to evaluate the security of the device. The challenge message, 1135 characters long, was solved by William Friedman, assisted by Solomon Kullback, Frank Rowlett and Abraham Sinkov, in 2 hours and 41 minutes.

References

Alexander von Kryha, "Coding machine", U.S. patent 1,744,347 Alan G. Konheim, Cryptanalysis of a Kryha Machine, EUROCRYPT 1982, pp49–64. Cipher A. Deavours and Louis Kruh, "Machine Cryptography and Modern Cryptanalysis", Artech House, 1985, chapter IV.

External links Media related to Kryha at Wikimedia Commons Jerry Proc's pages on the Kryha: Standard, Electrical and Lilliput. Standard Kryha: Machine cover open and Machine cover closed Nick Gessler's page on the Kryha: Photographs

Illustrations

Kryha: The inner ring stepped an irregular number of places with each lever press, changing the encryption in a complex manner. — The inner ring stepped an irregular number of places with each lever press, changing the encryption in a complex manner.

Worked examples

Example 1 — a first encounter with Kryha

Start with the simplest possible case. Write down what Kryha claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Kryha before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Kryha ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Kryha

In research: Kryha appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Kryha in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Kryha is common in secondary-school and first-year university syllabi. It links to neighbouring topics Encryption devices, so understanding it makes those chapters shorter.
In everyday life: Look for Kryha outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Kryha in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kryha means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Kryha out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kryha in simple terms?

Why does Kryha matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Kryha?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Kryha.