CRYPTOGRAPHY FINAL STUDY GUIDE 2026
CORRECT SOLUTIONS GRADED A+
◍ asymmetric key-based encryption
-typical methods. Answer: RSA
DSA
El Gamal
◍ Symmetric key-based encryption
-Typical Methods. 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. Answer: RC2(40 bit key size)
RC5(Variable block size)
IDEA
DES
3DES
AES (Rijndael)
Blowfish
,twofish
◍ stream encryption. Answer: RC4
Chacha
◍ Rainbow Attack. Answer: The method of knowing the mapping
between the hashed values and the original data
◍ Dictionary-type attack. Answer: a brute force analysis
◍ ∉. Answer: does not belong to
when an object is not in a set
◍ ∈. Answer: Belongs to
when an object is within a set
◍ ⊆. Answer: subset
subset has fewer elements or equal to the set
◍ A ∪ B. Answer: union (objects that belong to set A or set B)
◍ |. Answer: such that
◍ A ∩ B. Answer: Intersection: in both A and B
,◍ Enigma Machine -Cypher 10. 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. 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. 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. 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. 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. Answer: Encoding method, rather than a
cipher, that works by translating characters into sequences of dots (.)
and dashes (-)
◍ Playfair Cipher 4. 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. Answer: Makes use of a grid and which maps the
letters into numeric values.
◍ Rail Code Cipher 2. Answer: Employs a method to scramble text
by writing it in a sequence across a number of rails.
◍ Pig Pen Cipher 1. 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.
◍ Encryption. Answer: in simplest terms is changing plaintext into
ciphertext
CORRECT SOLUTIONS GRADED A+
◍ asymmetric key-based encryption
-typical methods. Answer: RSA
DSA
El Gamal
◍ Symmetric key-based encryption
-Typical Methods. 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. Answer: RC2(40 bit key size)
RC5(Variable block size)
IDEA
DES
3DES
AES (Rijndael)
Blowfish
,twofish
◍ stream encryption. Answer: RC4
Chacha
◍ Rainbow Attack. Answer: The method of knowing the mapping
between the hashed values and the original data
◍ Dictionary-type attack. Answer: a brute force analysis
◍ ∉. Answer: does not belong to
when an object is not in a set
◍ ∈. Answer: Belongs to
when an object is within a set
◍ ⊆. Answer: subset
subset has fewer elements or equal to the set
◍ A ∪ B. Answer: union (objects that belong to set A or set B)
◍ |. Answer: such that
◍ A ∩ B. Answer: Intersection: in both A and B
,◍ Enigma Machine -Cypher 10. 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. 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. 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. 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. 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. Answer: Encoding method, rather than a
cipher, that works by translating characters into sequences of dots (.)
and dashes (-)
◍ Playfair Cipher 4. 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. Answer: Makes use of a grid and which maps the
letters into numeric values.
◍ Rail Code Cipher 2. Answer: Employs a method to scramble text
by writing it in a sequence across a number of rails.
◍ Pig Pen Cipher 1. 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.
◍ Encryption. Answer: in simplest terms is changing plaintext into
ciphertext
