encoding/stenography/RNG

Question 1

• periodic (repeatable sets)
• fast
• deterministic (predictable sets)

Answer 1

Pseudo-Random Number Generators (PRNGs)

Question 2

• aperiodic
• slow
• Non-deterministic

Answer 2

True Random Number Generators (TRNGs)

Question 3

8-bit values, up to 256 characters

Answer 3

ASCII

Question 4

16- bit values, up to 65,536 characters

Answer 4

UTF-16

Question 5

Secret Key encryption is needed for…

Answer 5

symmetric cryptography; makes use of a single secret key for both encryption and decryption.

Question 6

What specific algorithm is used in asymmetric cryptography overcome the weakness of symmetric cryptography through secret key encryption?

Answer 6

Diffie-Hellman is a widely used key exchange algorithm used to exchange the secret key in symmetric cryptography.

Question 7

Aescrypt

Answer 7

encrypts individual files

Question 8

Bitlocker

Answer 8

encrypts full disks

Question 9

FileVault

Answer 9

encrypts full disks

Question 10

Pseudo-Random Number Generators (PRNGs)

Answer 10

• periodic repeats the random numbers after a given time

* They are fast deterministic and are useful in producing a repeatable set of random numbers.

Question 11

True Random Number Generators (TRNGs)

Answer 11

•This method generates a true random number and uses some form of random
process.
•Overall, the method is generally slow, but is non-deterministic and aperiodic.

Question 12

• Poly-alphabetic cipher
• Like multiple Caesars
• based on a keyword
• difficult to guess

Answer 12

Vigenere

Question 13

• Encrypts two letters instead of one, this makes it more complex.
• 5x5 table
• based on a keyword and rule set
• Removes repeating letters

Answer 13

Playfair

Question 14

• Mono-alphabetic substitution cipher
• maps plaintext characters to symbols rather than to letters
• 2 square grids, 2 X-shaped grids, dots.
• Easy to remember

Answer 14

Pigpen

Question 15

• Makes use of a grid

* maps the letters into numeric values.

Answer 15

BIFID

Question 16

• Transposition cipher
• encrypts the message by altering each letter on a different row
• message must then be written down left to right and put into rows

Answer 16

Rail Fence (Zig-Zag)

Question 17

• mitigates frequency analysis
• mono-alphabetic
• mappings depend number of occurrences for a letter

Answer 17

homophonic substitution code

Question 18

• Can optionally use four 5x5 matrices arranged in square
• 25 letters
• bigrams.
• Maps to numbers

Answer 18

Four-square Cipher

extension of BIFID?

Question 19

• poly-alphabetic
• substitution cipher
• secret key
• letters could not be ciphered as itself.

Answer 19

Enigma Machine

Question 20

• substitution cipher
• maps letters to numbers
• Uses mod math algorithm

Answer 20

Affine Cipher

Question 21

• transposition cipher
• 36 letter alphabet
• Polybius square
• single columnar

Answer 21

ADFVGX Cipher

Question 22

• poly-Alphabet

* Turning produced different ciphertexts.

Answer 22

Cipher Disk

Question 23

Examples of poly-alphabetic ciphers

Answer 23

Vigenere
Cipher disk
Enigma machine