8/4/25, 1:03 AM Introduction to Cryptography - D334
Introduction to Cryptography - D334 COMPLETE
QUESTIONS AND CORRECT DETAILED ANSWERS
\VERIFIED SOLUTIONS \LATEST UPDATE 2025
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
Enigma Machine - challenge was thus to determine both the algorithm used and the key.
Cypher 10 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.
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
One-time pad cypher8 to be used, each time.
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
Vigenere Cipher 7 mappings, depending on the position of the keyword, making guessing
more difficult.
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
Ceasar Cipher6 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.
/ 1/38
,8/4/25, 1:03 AM Introduction to Cryptography - D334
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
Pig Pen Cipher 1 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.
XOR the following 1100010101101101
0101110101010111
1001100000111010
RSA
asymmetric key-based
encryption DSA
-typical methods El Gamal
RC2- 40 bit key size 64 bit block
RC4- (Stream Cipher)- Used in SSL and WEP
Symmetric key-based RC5- (Variable Key size, 32, 64, or
encryption 128 bit block size) AES- (128, 192
-Typical Methods
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)
RC2(40 bit key size)
RC5(Variable
block size) IDEA
DES
Block Encryption
3DES
AES
(Rijndael)
Blowfish
/ 2/38
,8/4/25, 1:03 AM Introduction to Cryptography - D334
twofish
RC4
stream encryption
Chacha
The method of knowing the mapping between the
Rainbow Attack
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
/ 3/38
, 8/4/25, 1:03 AM Introduction to Cryptography - D334
One-time pad is considered to be unbreakable since it only uses its cipher code
once.
This method repeats the random numbers after a given
Pseudo-Random Number
time (periodic). They are fast and are also deterministic
Generators (PRNGs)
and are useful in producing a repeatable set of random
numbers.
is cipher cracking methodology that involves
identifying patterns and variations in the probability of
Frequency Analysis
codes. i.e. a three-letter ciphered text combination
spotted at the beginning of a string too often could tip
us off that those three letters correlate the letters THE
in the English alphabet.
This method generates a true random number and uses some
form of random
True Random Number process. One approach is to monitor the movements of
Generators (TRNGs)
a mouse pointer on a screen or from the pauses
between keystrokes. Overall, the method is generally
slow,
especially if it involves human interaction, but is non-deterministic
and aperiodic.
/ 4/38
Introduction to Cryptography - D334 COMPLETE
QUESTIONS AND CORRECT DETAILED ANSWERS
\VERIFIED SOLUTIONS \LATEST UPDATE 2025
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
Enigma Machine - challenge was thus to determine both the algorithm used and the key.
Cypher 10 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.
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
One-time pad cypher8 to be used, each time.
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
Vigenere Cipher 7 mappings, depending on the position of the keyword, making guessing
more difficult.
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
Ceasar Cipher6 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.
/ 1/38
,8/4/25, 1:03 AM Introduction to Cryptography - D334
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
Pig Pen Cipher 1 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.
XOR the following 1100010101101101
0101110101010111
1001100000111010
RSA
asymmetric key-based
encryption DSA
-typical methods El Gamal
RC2- 40 bit key size 64 bit block
RC4- (Stream Cipher)- Used in SSL and WEP
Symmetric key-based RC5- (Variable Key size, 32, 64, or
encryption 128 bit block size) AES- (128, 192
-Typical Methods
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)
RC2(40 bit key size)
RC5(Variable
block size) IDEA
DES
Block Encryption
3DES
AES
(Rijndael)
Blowfish
/ 2/38
,8/4/25, 1:03 AM Introduction to Cryptography - D334
twofish
RC4
stream encryption
Chacha
The method of knowing the mapping between the
Rainbow Attack
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
/ 3/38
, 8/4/25, 1:03 AM Introduction to Cryptography - D334
One-time pad is considered to be unbreakable since it only uses its cipher code
once.
This method repeats the random numbers after a given
Pseudo-Random Number
time (periodic). They are fast and are also deterministic
Generators (PRNGs)
and are useful in producing a repeatable set of random
numbers.
is cipher cracking methodology that involves
identifying patterns and variations in the probability of
Frequency Analysis
codes. i.e. a three-letter ciphered text combination
spotted at the beginning of a string too often could tip
us off that those three letters correlate the letters THE
in the English alphabet.
This method generates a true random number and uses some
form of random
True Random Number process. One approach is to monitor the movements of
Generators (TRNGs)
a mouse pointer on a screen or from the pauses
between keystrokes. Overall, the method is generally
slow,
especially if it involves human interaction, but is non-deterministic
and aperiodic.
/ 4/38
