Western Governors University D 333
WGU D334 Introduction to
Cryptography Exam – Comprehensive
Practice Questions & Exam
Preparation
XOR the following 1100010101101101
0101110101010111
1001100000111010
asymmetric key-based encryption RSA
-typical methods DSA
El Gamal
Symmetric key-based encryption RC2- 40 bit key size 64 bit block
-Typical Methods RC4- (Stream Cipher)- Used in SSL and WEP
RC5- (Variable Key size, 32, 64, or 128 bit
block size) AES- (128, 192 or 256 bit key size,
128 bit block size) DES- (56 bit key size. 64 bit
Block size)
3DES- (112 bit key size, 64 bit block size)
,Block Encryption RC2(40 bit key size)
RC5(Variable block
size) IDEA
DES
3DES
AES
(Rijndael)
Blowfish
twofish
stream encryption RC4
Chacha
Rainbow Attack The method of knowing the mapping between the
hashed values and the original data
Dictionary-type attack a brute force analysis
∉ does not belong to
when an object is not in a set
∈ Belongs to
when an object is within a set
⊆ subset
subset has fewer elements or equal to the set
A∪B union (objects that belong to set A or set B)
| such that
A∩B Intersection: in both A and B
Enigma Machine -Cypher 10 Used a polyalphabetic substitution cipher, which did
not repeat within a reasonable time period, along
with a secret
key. For the cracking of the Enigma cipher, the
challenge was thus to determine both the algorithm
used and the key.
Enigma's main weakness, though, was that none of the
plain text letters could be ciphered as itself.
Four-square cipher9 Uses four 5 × 5 matrices arranged in a square, are where
each matrix contains 25 letters for encoding and
decoding
operations.
One-time pad cypher8 Cypher Code mapping that is only used once.
Advantage: it is essentially unbreakable.
Disadvantage: it takes lots of work as you would have
to generate the pad to be used, each time.
, Vigenere Cipher 7 Polyalphabetic cipher that involves using a different
mapping, based on a keyword, for each character of
the cipher. An advantage of this type of cipher is that
the same plaintext
character is likely to be coded to different mappings,
depending on the position of the keyword, making
guessing more difficult.
Ceasar Cipher6 Mono-alphabetic substitution cipher known as "shift"
cipher.
Involves plaintext being replaced by a letter some
fixed
number of positions down the alphabet. i.e., a
Caesar Cipher using a shift of +3 would mean a
plaintext letter A would result in a ciphertext letter D
(a shift of three positions to the right in the alphabet)
Morse Code cipher 5 Encoding method, rather than a cipher, that works by
translating characters into sequences of dots (.) and
dashes (-)
Playfair Cipher 4 5 × 5 matrix containing the alphabet less the letter J.
Cipher/decipher process consists of a set of rules
outlining use of column and row combinations.
BIFID Cipher 3 Makes use of a grid and which maps the letters into
numeric values.
Rail Code Cipher 2 Employs a method to scramble text by writing it in a
sequence across a number of rails.
Pig Pen Cipher 1 Mono- alphabetic substitution cipher that makes use of
mapping plaintext characters to graphical
characters rather than to alphabetic ones. i.e.
A=(pick a symbol), vs A=(pick a
letter). Disadvantage: once the mapping is known, it is
difficult to keep the message secret.
Encryption in simplest terms is changing plaintext into ciphertext
Decryption The process of converting a ciphertext into plaintext.
AESCrypt Encrypt individual files and encrypt full disks with
options such as Bitlocker and FileVault
Mono-alphabetic c code or substitution is where a single mapping from
our alphabet to a cipher alphabet is created. Many
early
cryptosystems used this.
Polyalphabetic refers to the mapping of our alphabet to a number
of cipher alphabets. This approach added a bit of
complexity to early cryptosystems.
One-time pad is considered to be unbreakable since it only uses
its cipher code once.
Pseudo-Random Number Generators This method repeats the random numbers after a
WGU D334 Introduction to
Cryptography Exam – Comprehensive
Practice Questions & Exam
Preparation
XOR the following 1100010101101101
0101110101010111
1001100000111010
asymmetric key-based encryption RSA
-typical methods DSA
El Gamal
Symmetric key-based encryption RC2- 40 bit key size 64 bit block
-Typical Methods RC4- (Stream Cipher)- Used in SSL and WEP
RC5- (Variable Key size, 32, 64, or 128 bit
block size) AES- (128, 192 or 256 bit key size,
128 bit block size) DES- (56 bit key size. 64 bit
Block size)
3DES- (112 bit key size, 64 bit block size)
,Block Encryption RC2(40 bit key size)
RC5(Variable block
size) IDEA
DES
3DES
AES
(Rijndael)
Blowfish
twofish
stream encryption RC4
Chacha
Rainbow Attack The method of knowing the mapping between the
hashed values and the original data
Dictionary-type attack a brute force analysis
∉ does not belong to
when an object is not in a set
∈ Belongs to
when an object is within a set
⊆ subset
subset has fewer elements or equal to the set
A∪B union (objects that belong to set A or set B)
| such that
A∩B Intersection: in both A and B
Enigma Machine -Cypher 10 Used a polyalphabetic substitution cipher, which did
not repeat within a reasonable time period, along
with a secret
key. For the cracking of the Enigma cipher, the
challenge was thus to determine both the algorithm
used and the key.
Enigma's main weakness, though, was that none of the
plain text letters could be ciphered as itself.
Four-square cipher9 Uses four 5 × 5 matrices arranged in a square, are where
each matrix contains 25 letters for encoding and
decoding
operations.
One-time pad cypher8 Cypher Code mapping that is only used once.
Advantage: it is essentially unbreakable.
Disadvantage: it takes lots of work as you would have
to generate the pad to be used, each time.
, Vigenere Cipher 7 Polyalphabetic cipher that involves using a different
mapping, based on a keyword, for each character of
the cipher. An advantage of this type of cipher is that
the same plaintext
character is likely to be coded to different mappings,
depending on the position of the keyword, making
guessing more difficult.
Ceasar Cipher6 Mono-alphabetic substitution cipher known as "shift"
cipher.
Involves plaintext being replaced by a letter some
fixed
number of positions down the alphabet. i.e., a
Caesar Cipher using a shift of +3 would mean a
plaintext letter A would result in a ciphertext letter D
(a shift of three positions to the right in the alphabet)
Morse Code cipher 5 Encoding method, rather than a cipher, that works by
translating characters into sequences of dots (.) and
dashes (-)
Playfair Cipher 4 5 × 5 matrix containing the alphabet less the letter J.
Cipher/decipher process consists of a set of rules
outlining use of column and row combinations.
BIFID Cipher 3 Makes use of a grid and which maps the letters into
numeric values.
Rail Code Cipher 2 Employs a method to scramble text by writing it in a
sequence across a number of rails.
Pig Pen Cipher 1 Mono- alphabetic substitution cipher that makes use of
mapping plaintext characters to graphical
characters rather than to alphabetic ones. i.e.
A=(pick a symbol), vs A=(pick a
letter). Disadvantage: once the mapping is known, it is
difficult to keep the message secret.
Encryption in simplest terms is changing plaintext into ciphertext
Decryption The process of converting a ciphertext into plaintext.
AESCrypt Encrypt individual files and encrypt full disks with
options such as Bitlocker and FileVault
Mono-alphabetic c code or substitution is where a single mapping from
our alphabet to a cipher alphabet is created. Many
early
cryptosystems used this.
Polyalphabetic refers to the mapping of our alphabet to a number
of cipher alphabets. This approach added a bit of
complexity to early cryptosystems.
One-time pad is considered to be unbreakable since it only uses
its cipher code once.
Pseudo-Random Number Generators This method repeats the random numbers after a
