Introduction to Cryptography -
D334 with correct answers
2025/2026
XOR the following
0101110101010111
1001100000111010
------------------ - correct answers1100010101101101
asymmetric key-based encryption
-typical methods - correct answersRSA
DSA
El Gamal
Symmetric key-based encryption
-Typical Methods - correct answersRC2- 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 answersRC2(40 bit key size)
,RC5(Variable block size)
IDEA
DES
3DES
AES (Rijndael)
Blowfish
twofish
stream encryption - correct answersRC4
Chacha
Rainbow Attack - correct answersThe method of knowing the mapping between the hashed
values and the original data
Dictionary-type attack - correct answersa brute force analysis
∉ - correct answersdoes not belong to
when an object is not in a set
∈ - correct answersBelongs to
when an object is within a set
⊆ - correct answerssubset
subset has fewer elements or equal to the set
A ∪ B - correct answersunion (objects that belong to set A or set B)
,| - correct answerssuch that
A ∩ B - correct answersIntersection: in both A and B
Enigma Machine -Cypher 10 - correct answersUsed 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 answersUses 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 answersCypher 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 answersPolyalphabetic 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 answersMono-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 answersEncoding method, rather than a cipher, that works by
translating characters into sequences of dots (.) and dashes (-)
Playfair Cipher 4 - correct answers5 × 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 answersMakes use of a grid and which maps the letters into numeric
values.
Rail Code Cipher 2 - correct answersEmploys a method to scramble text by writing it in a
sequence across a number of rails.
Pig Pen Cipher 1 - correct answersMono- 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 - correct answersin simplest terms is changing plaintext into ciphertext
Decryption - correct answersThe process of converting a ciphertext into plaintext.
AESCrypt - correct answersEncrypt individual files and encrypt full disks with options such as
Bitlocker and FileVault
Mono-alphabetic - correct answersc code or substitution is where a single mapping from our
alphabet to a cipher alphabet is created. Many early cryptosystems used this.
Polyalphabetic - correct answersrefers to the mapping of our alphabet to a number of cipher
alphabets. This approach added a bit of complexity to early cryptosystems.
D334 with correct answers
2025/2026
XOR the following
0101110101010111
1001100000111010
------------------ - correct answers1100010101101101
asymmetric key-based encryption
-typical methods - correct answersRSA
DSA
El Gamal
Symmetric key-based encryption
-Typical Methods - correct answersRC2- 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 answersRC2(40 bit key size)
,RC5(Variable block size)
IDEA
DES
3DES
AES (Rijndael)
Blowfish
twofish
stream encryption - correct answersRC4
Chacha
Rainbow Attack - correct answersThe method of knowing the mapping between the hashed
values and the original data
Dictionary-type attack - correct answersa brute force analysis
∉ - correct answersdoes not belong to
when an object is not in a set
∈ - correct answersBelongs to
when an object is within a set
⊆ - correct answerssubset
subset has fewer elements or equal to the set
A ∪ B - correct answersunion (objects that belong to set A or set B)
,| - correct answerssuch that
A ∩ B - correct answersIntersection: in both A and B
Enigma Machine -Cypher 10 - correct answersUsed 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 answersUses 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 answersCypher 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 answersPolyalphabetic 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 answersMono-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 answersEncoding method, rather than a cipher, that works by
translating characters into sequences of dots (.) and dashes (-)
Playfair Cipher 4 - correct answers5 × 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 answersMakes use of a grid and which maps the letters into numeric
values.
Rail Code Cipher 2 - correct answersEmploys a method to scramble text by writing it in a
sequence across a number of rails.
Pig Pen Cipher 1 - correct answersMono- 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 - correct answersin simplest terms is changing plaintext into ciphertext
Decryption - correct answersThe process of converting a ciphertext into plaintext.
AESCrypt - correct answersEncrypt individual files and encrypt full disks with options such as
Bitlocker and FileVault
Mono-alphabetic - correct answersc code or substitution is where a single mapping from our
alphabet to a cipher alphabet is created. Many early cryptosystems used this.
Polyalphabetic - correct answersrefers to the mapping of our alphabet to a number of cipher
alphabets. This approach added a bit of complexity to early cryptosystems.
