CH3: Public Key Cryptography and Message Authentication

6.It is computationally infeasible to find any pair (x, y) such that H(x) = H(y). A hash function with this property is referred to as __________ . A. collision resistant B. preimage resistant C. one-way D. weak collision resistant

A. collision resistant

5.The purpose of a ___________ is to produce a "fingerprint" of a file, message, or other block of data. A. hash function B. public key C. message authentication D. cipher encryption

A. hash function

9. __________ is a term used to describe encryption systems that simultaneously protect confidentiality and authenticity (integrity) of communications.

Authenticated encryption

1.________ protects against passive attacks (eavesdropping). A. Obfuscation B. Encryption C. SCR D. Message authentication

B. Encryption

3.__________ is a procedure that allows communicating parties to verify that received messages are authentic. A. ECB B. Message authentication C. Passive attack D. Encryption

B. Message authentication

2.The most important hash function is ________ . A. MAC B. SHA C. OWH D. ECB

B. SHA

7."It is easy to generate a code given a message, but virtually impossible to generate a message given a code" describes the __________ hash function property. A. second preimage resistant B. preimage resistant C. strong collision resistant D. collision resistant

B. preimage resistant

9.Secure Hash Algorithms with hash value lengths of 256, 384, and 512 bits are collectively known as _________ . A. SHA-0 B. SHA-3 C. SHA-2 D. SHA-1

C. SHA-2

8.The __________ property protects against a sophisticated class of attack known as the birthday attack. A. preimage resistant B. one-way C. collision resistant D. second preimage resistant

C. collision resistant

10. The key algorithmic ingredients of __________ are the AES encryption algorithm, the CTR mode of operation, and the CMAC authentication algorithm.

CCM

10.Public key cryptography is __________ . A. bit patterned B. one key C. symmetric D. asymmetric

D. asymmetric

4. If the message includes a _________ the receiver is assured that the message has not been delayed beyond that normally expected for network transit. A. sequence number B. shared key C. error detection code D. timestamp

D. timestamp

7. The two most widely used public key algorithms are RSA and _________ .

Diffie-Hellman

2. Private key encryption is used to produce digital signatures which provide an enhanced form of message authentication.

F

4. The two important aspects of encryption are to verify that the contents of the message have not been altered and that the source is authentic.

F

6. Message encryption alone provides a secure form of authentication.

F

9. Cryptographic hash functions generally execute slower in software than conventional encryption algorithms such as DES.

F

8. The _________ was developed by NIST and published as a federal information processing standard in 1993.

SHA

1. Public key algorithms are useful in the exchange of conventional encryption keys.

T

10. The main advantage of HMAC over other proposed hash based schemes is that HMAC can be proven secure, provided that the embedded hash function has some reasonable cryptographic strengths.

T

3. The strength of a hash function against brute-force attacks depends solely on the length of the hash code produced by the algorithm.

T

5. In the ECB mode of encryption if an attacker reorders the blocks of ciphertext then each block will still decrypt successfully, however, the reordering may alter the meaning of the overall data sequence.

T

7. Because of the mathematical properties of the message authentication code function it is less vulnerable to being broken than encryption.

T

8. In addition to providing authentication, a message digest also provides data integrity and performs the same function as a frame check sequence.

T

6. As with symmetric encryption, there are two approaches to attacking a secure hash function: brute-force attack and ___________ .

cryptanalysis

4. Like the MAC, a __________ accepts a variable size message M as input and produces a fixed size message digest H(M) as output. Unlike the MAC, it does not take a secret key as input.

hash function

1. Protection against active attacks (falsification of data and transactions) is known as ___________ .

message authentication

2. The __________ property is the "one-way" property and is important if the authentication technique involves the use of a secret value.

preimage resistant

3. The __________ approach has two advantages: it provides a digital signature as well as message authentication and it does not require the distribution of keys to communicating parties.

public-key

5. The __________ property guarantees that it is impossible to find an alternative message with the same hash value as a given message, thus preventing forgery when an encrypted hash code is used.

second preimage resistant