Chapter 6 Flashcards
(78 cards)
4 fundamental goals of cryptography
- confidentiality
- integrity
- authentication
- non-repudiation
which goal ensures data remains private?
Confidentiality
Integrity
Authentication
Non-repudiation
Confidentiality
which kind of cryptography uses a shared secret key?
Symmetric
which kind of cryptography uses a combiniation public and private key?
asymmetric
which goal ensures that data is not altered without authorization?
Confidentiality
Integrity
Authentication
Non-Repudiation
Integrity
what do encrypted message digests (digital signatures) enforce?
integrity
which goal verifies the claimed identity of system users?
Confidentiality
Integrity
Authentication
Non-Repudiation
Authentication
What does a challenge-response protocol prove?
Authentication
which goal assures that someone cannot claim they never did something?
Confidentiality
Integrity
Authentication
Non-Repudiation
Non-Repudiation
which cryptosystem ensures nonrepudiation?
asymmetric
what is key space?
the range of values that are valid for use as a key for an algorithm
2^n where n is the bit size of the key
algorithms are made known and public, allowing anyone to examine and test them to ensure that a cryptographic system is secure even if everything about they system except the key is known
Kerckhoff’s principle
which standard defines the hardware and software requirements for cryptographic modules used by the federal government?
FIPS - Federal Information Processing Standard
random number that acts as a placeholder variable
nonce
key escrow
a cryptographic key is stored with a third party (recovery agent) for safekeeping
work function
the amount of time it takes to brute-force an encryption system
how is a code different than a cipher
a cipher is a mathematical function that hides the true meaning of the original message. A code works on words or phrases and can be used to shorten phrases and is not necessarily meant to hide the meaning of the message.
Requirements for successful use of one-time pad
- key must be generated randomly
- key must be at least as long as the message
- pads must be protected against physical disclosure
- each pad must be used only one time
in this cipher, the encryption key is as long as the message and is chosen from a common book, newspaper, or magazine
running key cipher / book cipher
this cipher operates on chunks of a messages
block ciphers
this cipher operates on one character or bit of a message at a time
stream ciphers
key management best practices (3)
store keys securely
select keys using an approach that has as much randomness as possible
destroy keys when they are no longer needed
in what type of cryptography is the same key used to encrypt and decrypt the message?
symmetric
secret key
private key
“S”ymmetric = “S”ame key
4 problems of symmetric key cryptography
- key distribution - how do you share a key securely?
- does not implement non-repudiation
- not scalable - need to have a separate shared key for each person you talk to
- keys must be regenerated often
