As suggested by the title, it works by running DES three times with three different 56-bit keys. Key 1 encrypts the plaintext, key 2 decrypts the ciphertext, and key 3 encrypts the decrypted cipher text. The reason this is stronger than DES alone is due to the use of three keys.

However, it's vulnerable to known plaintext attacks and meet-in-the-middle attacks for having the same algorithm repeated a few times.]]>

3DES

Triple Data Encryption Standard

The Triple Data Encryption Standard was derived (3DES) was derived from DES, when DES began to falter as a secure form of encryption and before AES was developed.

As suggested by the title, it works by running DES three times with three different 56-bit keys. Key 1 encrypts the plaintext, key 2 decrypts the ciphertext, and key 3 encrypts the decrypted cipher text. The reason this is stronger than DES alone is due to the use of three keys.

However, it's vulnerable to known plaintext attacks and meet-in-the-middle attacks for having the same algorithm repeated a few times.

As suggested by the title, it works by running DES three times with three different 56-bit keys. Key 1 encrypts the plaintext, key 2 decrypts the ciphertext, and key 3 encrypts the decrypted cipher text. The reason this is stronger than DES alone is due to the use of three keys.

However, it's vulnerable to known plaintext attacks and meet-in-the-middle attacks for having the same algorithm repeated a few times.

National Institute of Standards and Technology

https://www.comparitech.com/blog/information-security/3des-encryption/

Comparitech

1999

Josh Lake

http://www.crypto-it.net/eng/attacks/meet-in-the-middle.html

Encryption

English

Encryption

Encryption

ADFGVX Cipher

ADFGVX Cipher

The ADFGVX cipher was developed by Colonel Fritz Nebel and introduced in March 1918. Germany used it as a field cipher during WWI. It was named the ADFGVX cipher for the letters used to create ciphertext, chosen for their distinctiveness in morse code. Its cryptanalysis requires two keys- a key matrix and a keyword. The key matrix is a 6x6 square with the letters A, D, F, G, V, and X above and to the side- populated with letters from the plaintext message and numbers 0-9. The first step of encoding is done through substitution- each letter of the plaintext is replaced by its two intersecting ADFGVX letters. The next step includes writing the enciphered text under the keyword in horizontal rows. A columnar transposition is then performed- the keyword is rearranged into alphabetical order and the vertical columns with each letter of the key word. The final ciphertext is formed by reading off the columns in vertical fashion. To decipher the ciphertext, you reverse the steps- using the same keyword and key matrix.

Fritz Nebel

http://practicalcryptography.com/ciphers/classical-era/adfgvx/

Practical Cryptography

1918

Practical Cryptography

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English

Cipher

Cipher

AES includes three block ciphers that identify the secret key lengths involved. In addition to the key lengths, these block ciphers differ with the number of rounds that plaintext is processed and transformed.

AES-128 | 128-bit key length | 10 rounds

AES-192 | 192-bit key length | 12 rounds

AES-256 | 256-bit key length | 14 rounds]]>

AES

Advanced Encryption Standard

The Advanced Encryption Standard (AES) is a symmetric block cipher that was began development in 1997 to replace the Data Encryption Standard. It chosen as the U.S. federal government standard encryption algorithm in 2002. In 2003, it became the standard for classified information.

AES includes three block ciphers that identify the secret key lengths involved. In addition to the key lengths, these block ciphers differ with the number of rounds that plaintext is processed and transformed.

AES-128 | 128-bit key length | 10 rounds

AES-192 | 192-bit key length | 12 rounds

AES-256 | 256-bit key length | 14 rounds

AES includes three block ciphers that identify the secret key lengths involved. In addition to the key lengths, these block ciphers differ with the number of rounds that plaintext is processed and transformed.

AES-128 | 128-bit key length | 10 rounds

AES-192 | 192-bit key length | 12 rounds

AES-256 | 256-bit key length | 14 rounds

The National Institute of Standards and Technology

https://searchsecurity.techtarget.com/definition/Advanced-Encryption-Standard

Searchsecurity.techtarget

2002

Corinne Bernstein, Michael Cobb, GEM100, Borys Pawliw

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English

Encryption

Encryption

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

]]>

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

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

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

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One method of deciphering a Caesar Cipher is by using a brute approach and noting the frequency of each letter used- then comparing those frequencies to a frequency distribution chart of the alphabet. For example, 'E' is the most freqently used letter in the alphabet. Theoretically, if 'G' is the most freqently used letter in the ciphertext, you may able to shift the alphabets so that 'E' aligns with 'G' to decipher the rest of the ciphertext.]]>

Caesar Cipher

Caesar Cipher

The Caesar Cipher is one of the oldest ciphers, used by Julius Caesar to communicate with his generals. It works by shifting the alphabet down by a fixed number, or key. Due to the simplicity, it can be broken if the crypanalyst knows that a simple substitution method has been used to get the ciphertext, or the Caesar Cipher itself.

One method of deciphering a Caesar Cipher is by using a brute approach and noting the frequency of each letter used- then comparing those frequencies to a frequency distribution chart of the alphabet. For example, 'E' is the most freqently used letter in the alphabet. Theoretically, if 'G' is the most freqently used letter in the ciphertext, you may able to shift the alphabets so that 'E' aligns with 'G' to decipher the rest of the ciphertext.

One method of deciphering a Caesar Cipher is by using a brute approach and noting the frequency of each letter used- then comparing those frequencies to a frequency distribution chart of the alphabet. For example, 'E' is the most freqently used letter in the alphabet. Theoretically, if 'G' is the most freqently used letter in the ciphertext, you may able to shift the alphabets so that 'E' aligns with 'G' to decipher the rest of the ciphertext.

Julius Caesar

https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/c/Caesar_cipher.htm

Cs.mcgill.ca

44 B.C.

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English

Cipher

Cipher

Confederate Cipher Disk

Confederate Cipher Disk

The Confederate Cipher Disk was used in The American Civil War by the Confederate Army. Created by Francis LaBarre and based on the VigenĂ¨re Cipher, it consisted of two brass discs with the alphabet on each. As a mechanical cipher tool, it allowed the Confederate Army secured communication.

Francis LaBarre

https://www.cryptomuseum.com/crypto/usa/ccd/index.htm

Cyptomuseum

1861- 1865

Cryptomuseum

https://crypto.omeka.net/admin/items/show/4

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English

Replica

Brass Disc

The reason DES was vulnerable to brute-force attacks is because decryption was simply the inverse of encryption and used a 64-bit key- reduced to a 54-bit key due to parity checks. Therefore, it only took 2^56 ( or 72,057,594,037,927,936) attempts to find the correct key used to encrypt a plaintext message. ]]>

DES

Data Encryption Standard

The Data Encryption Standard (DES) is an outdated form of encryption that became vulnerable to brute-force attacks, and was replaced by AES. Developed by IBM in the 1970s, it was used by the U.S. government as their official Federal Information Processing Standard and officially cycled out by 2005.

The reason DES was vulnerable to brute-force attacks is because decryption was simply the inverse of encryption and used a 64-bit key- reduced to a 54-bit key due to parity checks. Therefore, it only took 2^56 ( or 72,057,594,037,927,936) attempts to find the correct key used to encrypt a plaintext message.

The reason DES was vulnerable to brute-force attacks is because decryption was simply the inverse of encryption and used a 64-bit key- reduced to a 54-bit key due to parity checks. Therefore, it only took 2^56 ( or 72,057,594,037,927,936) attempts to find the correct key used to encrypt a plaintext message.

IBM

https://searchsecurity.techtarget.com/definition/Data-Encryption-Standard

Searchsecurity.techtarget

1970s

Michael Cobb, Laura Biasci, Lyne Granum, and Frank Rundatz

https://crypto.omeka.net/admin/items/show/id/13

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English

Encryption

Encryption

In 1939, Alan Turing broke the cipher and developed a method to detect the settings on the Enigma and let the Allied Forced decipher messages. This was significant as it resulted in the Allied Forces evading German U-Boats in the Battle of the Atlantic.]]>

Enigma

Enigma

The Enigma was an electromechanical cipher machine used by Germany in WWII. It came in the form of a typewriter and was adopted by the German Army, Air Force, and Navy to secure communications.

In 1939, Alan Turing broke the cipher and developed a method to detect the settings on the Enigma and let the Allied Forced decipher messages. This was significant as it resulted in the Allied Forces evading German U-Boats in the Battle of the Atlantic.

In 1939, Alan Turing broke the cipher and developed a method to detect the settings on the Enigma and let the Allied Forced decipher messages. This was significant as it resulted in the Allied Forces evading German U-Boats in the Battle of the Atlantic.

Chiffriermaschinen AG

https://www.cryptomuseum.com/crypto/enigma/index.htm

Cryptomuseum

WWII

Cryptomuseum

https://www.cia.gov/news-information/featured-story-archive/2015-featured-story-archive/the-enigma-of-alan-turing.html

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English

Typewriter

Fialka

Fialka

Fialka was known as a more complex version of the Enigma, created by Russian military for communicating within the Soviet Union and Warsaw pact in the 1960s- early 1970s. Compared to the Enigma's three rotors, Fialka had ten rotors- giving way to approximately 8.6e50 configurations. When a Fialka machine was captured in 1967, the NSA built a computer to decrypt messages.

Russia

https://derekbruff.org/blogs/fywscrypto/historical-crypto/fialka-the-bigger-better-russian-enigma/

Derekbruff

1960s-early 1970s

Matthew Gu

https://crypto.omeka.net/items/show/5

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Russian

Cipher machine

Cipher machine