Crypto Study 3 Flashcards
What function does this stand for ^?
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.
What function does this symbol stand for? v
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
What function does this symbol represent? ~
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.
What function does this symbol represent? ⊕
The exclusive OR operation. If one value OR the other is TRUE then the result is TRUE. 1 + 1= 0 but 1 +0=1
What is a NONCE?
A random number that acts as a placeholder variable in mathematical functions.
Give an example of a NONCE.
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.
What is SPLIT KNOWLEDGE?
When information or privelige is split among different users so no one perosn has the ability to compromise the security of an environment.
What is a TRANSPOSITION CIPHER?
Rearrangement of letters
What is a SUBSTITUTION CIPHER?
Uses an encryption algorithm to replace the letters of a message
What other name is a ONE TIME PAD known as?
Vernam Cipher
What are the requirements or rules for keeping a ONE TIME PAD secure?
- Must be randomly generated.
- Must be physically protected against disclosure
- Can be used only ONCE
- Key must be at least as long as the message
What other name is a RUNNING KEY CIPHER known as?
A BOOK CIPHER
A Transpostion CI{HER is also known as a ________________ Cipher.
BLOCK
A STREAM CIPHER works on a _____ at a time
BIT
What causes CONFUSION in Cryptography?
When the relationship between the plaintext and the key is so complicated that moving the text around is not enough to decipher it
What causes DIFFUSION in Cryptography?
When a change in the plain text causes multiple changes in throughout the ciphertext.
What are some of the issues with SYMMETRIC KEY Cryptography?
- Key Distribution is problematic- must have a secure method to EXCHANGE keys
- Does not provide non-repudiation
- Not SCALABLE
- Keys have to be regenerated often- if a person leaves every key know (exchnaged) must be regenerated
How is SYMMETRIC KEY ENCRYPTION accomplished? (How many keys)
Each participant has ONE secret key that must be known to both parties. Two keys used.
How is ASYMMETRIC KEY encryption accomplished?
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.
What is the formula to determine the number of SYMMETRIC KEYS required?
Number of Keys= n(n-1)/2
