Crypto Study 1

Question 1

What function does this stand for ^?

Answer 1

The AND operation where both inputs have to be true for a true output value. Only an X and Y of 1 produce and output value of 1.

X=1 and Y=1

X+Y= 1

Question 2

What function does this symbol stand for? v

Answer 2

The OR operation. Only one value needs to be TRUE in order to produce a TRUE value.

e.g. 1 +0 = 1 but 0 = 0 = 0

Question 3

What function does this symbol represent? ~

Answer 3

The NOT operation. The NOT operation is the opposite of the function so a 1 with the NOT operation applied is 0 and vice versa.

Question 4

What function does this symbol represent? ⊕

Answer 4

The exclusive OR operation. If one value OR the other is TRUE then the result is TRUE. 1 + 1= 0 but 1 +0=1

Question 5

What is a NONCE?

Answer 5

A random number that acts as a placeholder variable in mathematical functions.

Question 6

Give an example of a NONCE.

Answer 6

An IV or initialization vector which is a random bit string that is the same length as the block size and is XORed with the message. They are used to create unique ciphertext everytime the the same message is encrypted using the SAME KEY.

Question 7

What is SPLIT KNOWLEDGE?

Answer 7

When information or privelige is split among different users so no one personn has the ability to compromise the security of an environment.

Question 8

What is a TRANSPOSITION CIPHER?

Answer 8

Rearrangement of letters

Question 9

What is a SUBSTITUTION CIPHER?

Answer 9

Uses an encryption algorithm to replace the letters of a message

Question 10

What other name is a ONE TIME PAD known as?

Answer 10

Vernam Cipher

Question 11

What are the requirements or rules for keeping a ONE TIME PAD secure?

Answer 11

1. Must be randomly generated.
2. Must be physically protected against disclosure
3. Can be used only ONCE
4. Key must be at least as long as the message

Question 12

What other name is a RUNNING KEY CIPHER known as?

Answer 12

A BOOK CIPHER​

Question 13

A Transpostion CIPHER is also known as a ________________ Cipher.

Answer 13

BLOCK

Question 14

A STREAM CIPHER works on a _____ at a time

Answer 14

BIT

Question 15

What causes CONFUSION in Cryptography?

Answer 15

When the relationship between the plaintext and the key is so complicated that moving the text around is not enough to decipher it

Question 16

What causes DIFFUSION in Cryptography?

Answer 16

When a change in the plain text causes multiple changes throughout the ciphertext.

Question 17

What are some of the issues with SYMMETRIC KEY Cryptography?

Answer 17

1. Key Distribution is problematic- must have a secure method to EXCHANGE keys
2. Does not provide non-repudiation
3. Not SCALABLE
4. Keys have to be regenerated often- if a person leaves every key must be regenerated

Question 18

How is SYMMETRIC KEY ENCRYPTION accomplished? (How many keys)

Answer 18

Each participant has ONE secret key that must be known to both parties. Two keys used.

Question 19

How is ASYMMETRIC KEY encryption accomplished?

Answer 19

Using a PUBLIC Key (known to all) and a PRIVATE KEY (Known only to one side).

Person encrypting uses the recipient’s PUBLIC KEY which is decrypted by the PRIVATE KEY of the recipinent.

Question 20

What is the formula to determine the number of SYMMETRIC KEYS required?

Answer 20

Number of Keys= n(n-1)/2