M-209
M-209
The M-209 was a cipher machine invented by Boris Hagelin or AB Cryptoteknik at the beginning of WWII. As a pin-and-lug cipher machine, it did not require electricity. During the war, German cryptanalysts called the machine "AM-1" for "American Machine #1".
In 1942, cryptanalysts from the US and UK had a debate over this machine. The British were concerned that the Italians would be able to read American Hagelin traffic, as they had been able to read Italian Hagelin traffic. However, the US chose to ignore this- citing that breaking the M-209 would be too difficult and time-consuming for the Axis powers. As it turned out, the Germans were able to read ~10% of American Hagelin traffic. This was 6% due to cryptanalysis and 4% due to captured keys. However, this decryption usually took 7-10 days- often rendering the message old and not useful.
Boris Hagelin
https://www.cryptomuseum.com/crypto/hagelin/m209/index.htm
Cryptomuseum
1940
Cryptomuseum
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Cryptomachine
M-94
M-94
The M-94 was a cipher device based off the polyalphabetic manual substitution cipher. It was created by US Army major Joseph Mauborgne in 1917 with inspiration from a similar device invented by Thomas Jefferson in 1795. In 1921, it was introduced to the Army.
This device consisted of 25 circular discs- each with a different mixed alphabet of 26 letters. Although the security of the pocket device wasn't impressive, companies like Doehler, Reeve, and Alcoa had produced 9,432 of these tools by 1943 for use in the US Army.
The growing obsolete nature of this cipher device would inspire the need for the M-209.
Joseph O. Mauborgne
https://www.campx.ca/crypto.html
Cryptographic Artifacts
1917-1943
Richard Brisson
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Cipher device
SIGABA
SIGABA
SIGABA was an electro-mechanical cipher machine created in the late 1930s by the US Army and Navy. It was considered an impressive cryptomachine in that time period to the degree that it was used throughout WWII and into the 1950s.
By the end of WWII, over 10,000 machines had been deployed. They were used notably by the US Navy in submarines and battleships. Although the number of machines was less than half the quantity of the Enigma machines used by the Germans, they still kept high-level communications secured. In fact, SIGABA has never been broken.
US Army and Navy
https://www.cryptomuseum.com/crypto/usa/sigaba/index.htm
Cryptomuseum
1930s-1950s
Cryptomuseum
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Cryptomachine
Frequency Analysis
Frequency Analysis
Frequency Analysis is a method of code breaking that works to decipher all substitution ciphers. This methods relies on the fact that some letters of the alphabet are used more than other letters of the alphabet. For example, 'E' is more commonly found than 'X'. In fact, 'E' is the most common letter of the English alphabet- appearing roughly 12% of the time in a given sample message compared to other letters.
The way that this analysis works is that by comparing the frequency of the alphabet applied to the ciphertext with the frequency of the plaintext alphabet, the analyst can began making estimations of what letter lines up with which. Once the analyst finds the key- the correct plaintext letter a ciphertext letter aligns with in the alphabet, they can shift the entire alphabet and be able to read the rest of the message.
Unknown
https://crypto.interactive-maths.com/frequency-analysis-breaking-the-code.html
Crypto Corner
Daniel Rodriguez-Clark
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Cipher
Atbash Cipher
Atbash Cipher
The Atbash Cipher is a monoalphabetic substitution cipher that is relatively simple and does not require a key. Instead of a key, the substitution simply relies on reversing the alphabet. Therefore, 'A' becomes 'Z', 'B' becomes 'Y', and so forth. This makes it a weak cipher in terms of how easy it is to decode. However, it does have one notable security measure- including numbers and punctuation on either side of the alphabet that also has to be reversed.
Israel (Hebrew origin)
https://crypto.interactive-maths.com/atbash-cipher.html
Crypto Corner
Daniel Rodriguez-Clark
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Hebrew, English
Hill Cipher
Hill Cipher
The Hill Cipher was developed in 1929 by Lester Hill. A digraph substitution cipher, it works using groups of letters to encrypt. However, it is different from other digraph substitution ciphers because it can work on different group sizes of letters- technically making it a polygraphic substitution cipher.
The Hill Cipher is also exceptional because it uses linear algebra, matrices, and arithmetic. This is a relatively significant amount of mathematics compared to other ciphers that can be used by hand and without a machine. For the example outlined in the images, the resulting ciphertext is: "APADJ TFTWLFJ".
Lester S. Hill
https://crypto.interactive-maths.com/hill-cipher.html
Crypto Corner
Daniel Rodriguez-Clark
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Cipher
Route Cipher
Route Cipher
A Route Cipher is a type of transposition cipher where you write the message into a grid box and read the letters in a certain route. This cipher was used by the Union forces during the Civil War. However, they took care to use it in a way that moved entire words around. In addition, sometimes the would encode a word or add null words to protect their message.
In order to create a route cipher, the dimensions of the put the plaintext in and decide what route you want it to follow. Once that is decided, the ciphertext becomes the letters in the order of the route. Therefore, decrypting a message requires the grid dimensions and route path as keys.
Unknown
https://crypto.interactive-maths.com/route-cipher.html
Crypto Corner
Daniel Rodriguez-Clark
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Cipher
Rail Fence Cipher
Rail Fence Cipher
The Rail Fence Cipher is form of transposition cipher that scrambles the letters. It does this by using a grid of x many rows, and the sender writes the plaintext in the grid in a vertical zig-zag pattern. The key for this cipher is the number of rows (x) that the sender decides to write the message across.
After writing the plaintext cross the grid, the ciphertext can be read off. This is done by reading each row across in descending order.
To decrypt, the letters just have to be arranged in the way they were put and read off in the zig-zag pattern. This makes it easy to decipher. Adding spaces between words into the grid can help, but only to a certain degree.
Unknown
https://crypto.interactive-maths.com/rail-fence-cipher.html
Crypto Corner
Daniel Rodriguez-Clark
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English
Cipher
Affine Cipher
Affine Cipher
The Affine Cipher is a form of substitution cipher that involves math. The shift of the alphabet- while transpositioning plaintext into ciphertext is determined by a mathematical equation. This equation is:
E(x) = (ax+b) mod m
E(x) = The number equaling the letter to be used in the cipher text
a, b = Any given number
x = the number correlating to the plaintext letter
mod m = A mathematical way (subtraction, division, etc.) to bring (ax+b) back within range of 26 for all answers.
To decrypt, the equation is c(x-b) mod m.
c = the modular multiplicative inverse of a
Unknown
https://crypto.interactive-maths.com/affine-cipher.html
Crypto Corner
Daniel Rodriguez-Clark
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English
Pigpen Cipher
Pigpen Cipher
The Pigpen Cipher is a form of substitution cipher that uses symbols, rather than other letters. Although its origin is unknown, this cipher was most famously used by the Freemasons in the 18th century- to the point that some know it as the Freemasons Cipher. However, it was also used during the Civil War. Imprisoned Union soldiers used it as a method of communication, while in Confederate camps.
The image for this entry shows the easiest way to remember what the symbols are for each letter. The symbol for each letter is the part of the grid/dot pattern that contains the letter. These symbols can be transposed directly without any rotation.
Unknown
https://crypto.interactive-maths.com/pigpen-cipher.html
Crypto Corner
Daniel Rodriguez-Clark
Cypher
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