Exam 12: Message Authentication Codes

One means of forming a MAC is to combine a cryptographic hash function in some fashion with a secret key.

the types of functions that may be used to produce an authenticator are grouped into three classes: hash function, message authentication code, and ___________ .

A __________ takes a variable length message and a secret key as input and produces an authentication code.

___________ is a term used to describe encryption systems that simultaneously protect confidentiality and authenticity of communications.

the _________ attack is when the attacker is looking for two messages M and M1 that produce the same hash: H(M) = H(M1)

the essential elements of any pseudorandom number generator are a __________ and a deterministic algorithm for generating a stream of pseudorandom bits.

With _________ authentication an opponent would have difficulty generating ciphertext that when decrypted would have valid error control bits.

A __________ is an algorithm that requires the use of a secret key.

Attacks on MACs can be grouped into two categories: brute-force attacks and __________ .

An alternative authentication technique involves the use of a secret key to generate a small fixed size block of data known as a __________ or MAC that is appended to the message.

HMAC is a widely used standardized _________ function and is implemented in many protocols and applications.

the __________ algorithm can be defined as using the cipher block chaining mode of operation of DES with an initialization vector of zero.

the MAC does not provide a digital signature because both sender and receiver share the same key.

the MAC function is a __________ function.

the appeal of __________ is that its designers have been able to prove an exact relationship between the strength of the embedded hash function and the strength of this form of authentication.

the GCM mode makes use of two functions: __________, which is a keyed hash function, and GCtR.

the key algorithmic ingredients of _________ are the AES encryption algorithm, the CtR mode of operation, and the CMAC authentication algorithm.

the approach taken by the transport Layer Security protocol and the Wireless transport Layer Security Protocol involve invoking HMAC _________ for each block of output wi.

the order in which the frame check sequence and encryption functions are performed is not critical for authentication.

An important characteristic of the MAC algorithm is that it needs to be reversible.