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Introduction to Cryptography C839 WGU – Complete Study Guide
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Introduction to Cryptography C839 WGU – Complete Study Guide
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Introduction to Cryptography C839 WGU – CompleteStudy Guide
Initializing Vector (Symmetric Algorithm Methods) Right Ans - -Used with:
-Nonce-Generated Initializing Vector
-Counter Initializing Vector
-Fixed Initializing Vector
-Random Initializing Vector
- FIPS Standard:
- FIPS 180-2: Secure Hash Algorithm (SAH-1)
Counter Right Ans -
Cryptography Right Ans - -Is the study of secure communication
mechanisms and methods
-Provides ways to encode a message so that it cannot be read by outsiders
Mono-Alphabet Substitution ciphers examples Right Ans - -AtBash
-Ceaser
-ROT13
-Scytale
Mono-Alphabet Substitution ciphers definition Right Ans - -Single Alphabet
-Preserve the underlying letter and word frequency and are vulnerable to
cryptoanalysis as a result
-Frequency analysis can be used to break Mono-Alphabet substitution
Atbash Cipher Right Ans - -Reverses the alphabet
- A becomes Z, B becomes Y ...
- Mono-Alphabet Substitution Cipher
-Used by ancient Hebrew scholars
,Ceasar Cipher Right Ans - -Choose some number by which to shift each
letter of the message
- right is "+" and left is "-"
- "2" and "1", A becomes C and C becomes B
- Mono-Alphabet Substitution Cipher
ROT-13 Right Ans - -Rotate all charachters 13 letters through the alphabet
- A becomes N, B becomes O ...
- Mono-Alphabet Substitution Cipher
Scytale Cipher Right Ans - -A simple transposition cipher
-system that employs a rod of a certain thickness around which was wrapped
a long, thin strip of parchment.
-Uses a rod of certain length to create and encrypt a message
-The same rod must be used to read and decrypt the message by the recipient
Multi-Alphabet Substitution Ciphers examples Right Ans - -The cipher disk
-The Vigenere cipher
-The Playfair Cipher
-The ADFGVX Ciper
-The Enigma Machine
Multi-Alphabet Substitution Ciphers definition Right Ans - -Adds
complexity by adding alphabets to be used for the substitution rounds
-Example:
-We are using three alphabets to do the shifting
-Each represented by a "+" or a "-" value
-When we run out of of alfahabets, we start over again with the first one,
effectivly "round robing"
,-This is dont through the text until it is all shifted
- " A DOG" (+1, -2, +1)
- "B BPH"
The Cipher Disk Right Ans - -Cryptographic device that uses two concentric
disks, each with an alphabet around the periphery.
-A physical device used to encrypt
-Invented by Leon Albert in 1466
-The cipher disk was poly-alphabetic
-Each time you turned the disk, you used a different cipher
-Multi-Alphabet Substitution Cipher
The Vigenere Cipher Right Ans - -Invented in 1553 by Giovan Battista
Bellaso
- It is named for Blasie de Vigenere who deveopled a stronger version cipher
-It is a method of encrypting by using a series of interwoven Caesar ciphers
based on the letters of a keyword
-Poly-alphabetic cipher system
-Friedrich Kasiski published the first successful attack against it in 1863
The Playfair Cipher Right Ans - -Invented by Charles Wheatstone in 1854
-Uses a 5 x 5 table containing a keyword or key phrase
-To generate the key table, one would first fill in the spaces in the table with
the letters of the keyword
-dropping duplicate letters
-Then fill in the remaining spaces with the rest of the letters of the alphabet in
order
, -The technique encrypts pairs of letters
-digraphs
-Instead of single letters as in the simple substitution cipher
-Playfair is significantly harder to break since the frequency analysis used for
simple substitution ciphers does not work with it
-Any sequence of 25 letters can be used as a key as long as it does not have
repeat letters in it
The ADFGVX Cipher Right Ans - - The first cipher used by German Army
during World War I
-Invented by Colonel Fritz Nebel in 1918
-A transposition cipher
-Used a polybius square with a single columnar transposition used to encode a
36 letter alphabet
-The key for this algorithm is a 6 x 6 square made up by the letters ADFSVX
-ADFGVX forms the otter row and column
-The rest of the table is comprised of the letters of the alphabet and the
numbers 0-9 distributed randomly in the square
-Each plain text character becomes two encrypted characters
The ENIGMA Machine Right Ans - -A multi-alphabet substitution cipher
using machinery to accomplish the encryption
-In World War II
-Germans used this as an electro-mechanical rotor-based cipher system
Symmetric Encryption (mathematically) Right Ans - - C = E(k,p)
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