D334 - Introduction to Cryptography
Exam Set Questions With Reviewed
Correct Detailed Answers
New Update!!
1. 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.
2. 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.
3. 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.
4. 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.
5. 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)
6. Morse Code cipher 5 - ANSWER Encoding method, rather than a cipher,
that works by translating characters into sequences of dots (.) and dashes (-
)
7. 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.
8. BIFID Cipher 3 - ANSWER Makes use of a grid and which maps the
letters into numeric values.
9. Rail Code Cipher 2 - ANSWER Employs a method to scramble text by
writing it in a sequence across a number of rails.
10. 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.
,11. Encryption - ANSWER in simplest terms is changing plaintext into
ciphertext
12. Decryption - ANSWER The process of converting a ciphertext into
plaintext.
13. AESCrypt - ANSWER Encrypt individual files and encrypt full disks with
options such as Bitlocker and FileVault
14. Mono-alphabetic - ANSWER c code or substitution is where a single
mapping from our alphabet to a cipher alphabet is created. Many early
cryptosystems used this.
15. Polyalphabetic - ANSWER refers to the mapping of our alphabet to a
number of cipher alphabets. This approach added a bit of complexity to
early cryptosystems.
16. One-time pad - ANSWER is considered to be unbreakable since it only
uses its cipher code once.
17. Pseudo-Random Number Generators (PRNGs) - ANSWER This method
repeats the random numbers after a given time (periodic). They are fast
and are also deterministic and are useful in producing a repeatable set of
random numbers.
, 18. Frequency Analysis - ANSWER is cipher cracking methodology that
involves identifying patterns and variations in the probability of 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.
19. True Random Number Generators (TRNGs) - ANSWER This method
generates a true random number and uses some form of random process.
One approach is to monitor the movements of 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.
20. Entropy - ANSWER measures level of unpredictability; in encryption
relates to the degree of uncertainty of the encryption process.
21. ASCII - ANSWER 8-bit values, up to 256 characters
22. UTF-16 - ANSWER 16- bit values, up to 65,536 characters
23. Hardware vs Software encryption - ANSWER Hardware encryption is
more efficient than software encryption.
24. Hardware Security Module (HSM) - ANSWER is a tamper-evident and
intrusion-resistant physical device that safeguards and manages
cryptographic keys and provides cryptographic processing.
Exam Set Questions With Reviewed
Correct Detailed Answers
New Update!!
1. 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.
2. 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.
3. 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.
4. 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.
5. 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)
6. Morse Code cipher 5 - ANSWER Encoding method, rather than a cipher,
that works by translating characters into sequences of dots (.) and dashes (-
)
7. 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.
8. BIFID Cipher 3 - ANSWER Makes use of a grid and which maps the
letters into numeric values.
9. Rail Code Cipher 2 - ANSWER Employs a method to scramble text by
writing it in a sequence across a number of rails.
10. 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.
,11. Encryption - ANSWER in simplest terms is changing plaintext into
ciphertext
12. Decryption - ANSWER The process of converting a ciphertext into
plaintext.
13. AESCrypt - ANSWER Encrypt individual files and encrypt full disks with
options such as Bitlocker and FileVault
14. Mono-alphabetic - ANSWER c code or substitution is where a single
mapping from our alphabet to a cipher alphabet is created. Many early
cryptosystems used this.
15. Polyalphabetic - ANSWER refers to the mapping of our alphabet to a
number of cipher alphabets. This approach added a bit of complexity to
early cryptosystems.
16. One-time pad - ANSWER is considered to be unbreakable since it only
uses its cipher code once.
17. Pseudo-Random Number Generators (PRNGs) - ANSWER This method
repeats the random numbers after a given time (periodic). They are fast
and are also deterministic and are useful in producing a repeatable set of
random numbers.
, 18. Frequency Analysis - ANSWER is cipher cracking methodology that
involves identifying patterns and variations in the probability of 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.
19. True Random Number Generators (TRNGs) - ANSWER This method
generates a true random number and uses some form of random process.
One approach is to monitor the movements of 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.
20. Entropy - ANSWER measures level of unpredictability; in encryption
relates to the degree of uncertainty of the encryption process.
21. ASCII - ANSWER 8-bit values, up to 256 characters
22. UTF-16 - ANSWER 16- bit values, up to 65,536 characters
23. Hardware vs Software encryption - ANSWER Hardware encryption is
more efficient than software encryption.
24. Hardware Security Module (HSM) - ANSWER is a tamper-evident and
intrusion-resistant physical device that safeguards and manages
cryptographic keys and provides cryptographic processing.
