Introduction to Cryptography - D334 Exam
Questions With Correct Answers
XOR the following
| | |
0101110101010111
1001100000111010
------------------ - CORRECT ANSWER✔✔-1100010101101101
| | |
asymmetric key-based encryption | |
-typical methods - CORRECT ANSWER✔✔-RSA
| | | |
DSA
El Gamal
|
Symmetric key-based encryption | |
-Typical Methods - CORRECT ANSWER✔✔-RC2- 40 bit key size 64 bit block
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RC4- (Stream Cipher)- Used in SSL and WEP
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RC5- (Variable Key size, 32, 64, or 128 bit block size)
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AES- (128, 192 or 256 bit key size, 128 bit block size)
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DES- (56 bit key size. 64 bit Block size)
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3DES- (112 bit key size, 64 bit block size)
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Block Encryption - CORRECT ANSWER✔✔-RC2(40 bit key size)
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,RC5(Variable block size) | |
IDEA
DES
3DES
AES (Rijndael)
|
Blowfish
twofish
stream encryption - CORRECT ANSWER✔✔-RC4
| | | |
Chacha
Rainbow Attack - CORRECT ANSWER✔✔-The method of knowing the mapping
| | | | | | | | | |
between the hashed values and the original data
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Dictionary-type attack - CORRECT ANSWER✔✔-a brute force analysis
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∉ - CORRECT ANSWER✔✔-does not belong to
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when an object is not in a set
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∈ - CORRECT ANSWER✔✔-Belongs to
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when an object is within a set
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⊆ - CORRECT ANSWER✔✔-subset
| | |
subset has fewer elements or equal to the set
| | | | | | | |
,A ∪ B - CORRECT ANSWER✔✔-union (objects that belong to set A or set B)
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| - CORRECT ANSWER✔✔-such that
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A ∩ B - CORRECT ANSWER✔✔-Intersection: in both A and B
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Enigma Machine -Cypher 10 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-Encoding method, rather than a
| | | | | | | | | | |
cipher, that works by translating characters into sequences of dots (.) and dashes
| | | | | | | | | | | | |
(-)
Playfair Cipher 4 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-Makes use of a grid and which maps the
| | | | | | | | | | | | | |
letters into numeric values.| | |
Rail Code Cipher 2 - CORRECT ANSWER✔✔-Employs a method to scramble text
| | | | | | | | | | | |
by writing it in a sequence across a number of rails.
| | | | | | | | | |
Pig Pen Cipher 1 - CORRECT ANSWER✔✔-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.
| | | | | | | | | | | |
Questions With Correct Answers
XOR the following
| | |
0101110101010111
1001100000111010
------------------ - CORRECT ANSWER✔✔-1100010101101101
| | |
asymmetric key-based encryption | |
-typical methods - CORRECT ANSWER✔✔-RSA
| | | |
DSA
El Gamal
|
Symmetric key-based encryption | |
-Typical Methods - CORRECT ANSWER✔✔-RC2- 40 bit key size 64 bit block
| | | | | | | | | | |
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 - CORRECT ANSWER✔✔-RC2(40 bit key size)
| | | | | | | |
,RC5(Variable block size) | |
IDEA
DES
3DES
AES (Rijndael)
|
Blowfish
twofish
stream encryption - CORRECT ANSWER✔✔-RC4
| | | |
Chacha
Rainbow Attack - CORRECT ANSWER✔✔-The method of knowing the mapping
| | | | | | | | | |
between the hashed values and the original data
| | | | | | |
Dictionary-type attack - CORRECT ANSWER✔✔-a brute force analysis
| | | | | | |
∉ - CORRECT ANSWER✔✔-does not belong to
| | | | | |
when an object is not in a set
| | | | | | |
∈ - CORRECT ANSWER✔✔-Belongs to
| | | |
when an object is within a set
| | | | | |
⊆ - CORRECT ANSWER✔✔-subset
| | |
subset has fewer elements or equal to the set
| | | | | | | |
,A ∪ B - CORRECT ANSWER✔✔-union (objects that belong to set A or set B)
| | | | | | | | | | | | | |
| - CORRECT ANSWER✔✔-such that
| | | |
A ∩ B - CORRECT ANSWER✔✔-Intersection: in both A and B
| | | | | | | | | |
Enigma Machine -Cypher 10 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-Encoding method, rather than a
| | | | | | | | | | |
cipher, that works by translating characters into sequences of dots (.) and dashes
| | | | | | | | | | | | |
(-)
Playfair Cipher 4 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-Makes use of a grid and which maps the
| | | | | | | | | | | | | |
letters into numeric values.| | |
Rail Code Cipher 2 - CORRECT ANSWER✔✔-Employs a method to scramble text
| | | | | | | | | | | |
by writing it in a sequence across a number of rails.
| | | | | | | | | |
Pig Pen Cipher 1 - CORRECT ANSWER✔✔-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.
| | | | | | | | | | | |
