CCNA Security Chapter 7 - 2014

1. The network administrator for an e-commerce website requires a service that prevents customers from claiming that legitimate orders are fake. What service provides this type of guarantee?
		authentication
		confidentiality
		integrity
	>>	nonrepudiation
2. How do modern cryptographers defend against brute-force attacks?
		Use statistical analysis to eliminate the most common encryption keys.
		Use an algorithm that requires the attacker to have both ciphertext and plaintext to conduct a successful attack.
	>>	Use a keyspace large enough that it takes too much money and too much time to conduct a successful attack.
		Use frequency analysis to ensure that the most popular letters used in the language are not used in the cipher message.
3. What is the basic method used by 3DES to encrypt plaintext?
		The data is encrypted three times with three different keys.
	>>	The data is encrypted, decrypted, and encrypted using three different keys.
		The data is divided into three blocks of equal length for encryption.
		The data is encrypted using a key length that is three times longer than the key used for DES.
4. A customer purchases an item from an e-commerce site. The e-commerce site must maintain proof that the data exchange took place between the site and the customer. Which feature of digital signatures is required?
		authenticity of digitally signed data
		integrity of digitally signed data
	>>	nonrepudiation of the transaction
		confidentiality of the public key
5. Why is RSA typically used to protect only small amounts of data?
		The keys must be a fixed length.
		The public keys must be kept secret.
	>>	The algorithms used to encrypt data are slow.
		The signature keys must be changed frequently.
6. An administrator requires a PKI that supports a longer lifetime for keys used for digital signing operations than for keys used for encrypting data. Which feature should the PKI support?
		certificate keys
		nonrepudiation keys
	>>	usage keys
		variable keys
7. Which three primary functions are required to secure communication across network links? (Choose three.)
		accounting
		anti-replay protection
	>>	authentication
		authorization
		confidentiality
	>>	integrity
8. Refer to the exhibit. Which type of cipher method is depicted?
		Caesar cipher
		stream cipher
		substitution cipher
	>>	transposition cipher
9. Which statement describes a cryptographic hash function?
	>>	A one-way cryptographic hash function is hard to invert.
		The output of a cryptographic hash function can be any length.
		The input of a cryptographic hash function has a fixed length.
		A cryptographic hash function is used to provide confidentiality.
10. Which statement is a feature of HMAC?
		HMAC is based on the RSA hash function.
		HMAC uses a secret key that is only known to the sender and defeats man-in-the-middle attacks.
	>>	HMAC uses a secret key as input to the hash function, adding authentication to integrity assurance.
		HMAC uses protocols such as SSL or TLS to provide session layer confidentiality.
11. Which encryption protocol provides network layer confidentiality?
	>>	IPsec protocol suite
		Keyed MD5
		Message Digest 5
		Secure Sockets Layer
		Secure Hash Algorithm 1
		Transport Layer Security
12. Refer to the exhibit. Which encryption algorithm is described in the exhibit?
	>>	3DES
		AES
		DES
		RC4
		SEAL
13. Which statement describes asymmetric encryption algorithms?
		They include DES, 3DES, and AES.
		They have key lengths ranging from 80 to 256 bits.
		They are also called shared-secret key algorithms.
	>>	They are relatively slow because they are based on difficult computational algorithms.
14. Which two statements correctly describe certificate classes used in the PKI? (Choose two.)
	>>	A class 0 certificate is for testing purposes.
		A class 0 certificate is more trusted than a class 1 certificate.
		The lower the class number, the more trusted the certificate.
		A class 5 certificate is for users with a focus on verification of email.
	>>	A class 4 certificate is for online business transactions between companies.
15. Two users must authenticate each other using digital certificates and a CA. Which option describes the CA authentication procedure?
		The CA is always required, even after user verification is complete.
	>>	The users must obtain the certificate of the CA and then their own certificate.
		After user verification is complete, the CA is no longer required, even if one of the involved certificates expires.
		CA certificates are retrieved out-of-band using the PSTN, and the authentication is done in-band over a network.
16. Which characteristic of security key management is responsible for making certain that weak cryptographic keys are not used?
	>>	verification
		exchange
		generation
		revocation and destruction
17. Which type of cryptographic key would be used when connecting to a secure website?
		DES key
		symmetric keys
		hash keys
	>>	digital signatures
18. Which algorithm is used to automatically generate a shared secret for two systems to use in establishing an IPsec VPN?
		ESP
		DES
		3DES
		AH
	>>	DH
		SSL
19. Which two non-secret numbers are initially agreed upon when the Diffie-Hellman algorithm is used? (Choose two.)
		elliptic curve invariant
	>>	generator
		pseudorandom nome
		binomial coefficient
	>>	prime modulus
		topological index
20. What does it mean when a hashing algorithm is collision resistant?
		Exclusive ORs are performed on input data and produce a digest.
		It is not feasible to compute the hash given the input data.
		It uses a two-way function that computes a hash from the input and output data.
	>>	Two messages with the same hash are unlikely to occur.

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