CRYPTOGRAPHIC HASH FUNCTIONS

Message authentication is achieved using a __________ .

MAC

__________ is a mechanism or service used to verify the integrity of a message.

Message authentication

What are some approaches to producing message authentication?

Message encryption, message authentication code, digital signature

__________ are measures of the number of potential collisions for a given hash value.

Preimages

The most important and widely used family of cryptographic hash functions is the ___ family.

SHA

Three new versions of SHA with hash value lengths of 256, 384, and 512 bits are collectively known as __________ .

SHA-2

Compare message hashes and MACs

The main difference is conceptual: while hashes are used to guarantee the integrity of data, a MAC guarantees integrity AND authentication.

Given a hash function H, with n possible outputs and a specific value H(x), if H is applied to k random inputs, what must be the value of k so that the probability that at least one input y satisfies H(y) = H(x) is 0.5?" is a reference to the __________ .

birthday attack

The effort required for a collision resistant attack is explained by a mathematical result referred to as the ___________ .

birthday paradox

The two categories of attacks on hash functions are _________________ attacks and cryptanalysis.

brute-force

A hash function that satisfies the properties of variable input size, fixed output size, efficiency, preimage resistant, second preimage resistant and __________________ is referred to as a strong hash function.

collision resistant

The evaluation criteria for SHA-3 are security, _____, and algorithm and implementation characteristics.

cost

A ________________ is an attack based on weaknesses in a particular cryptographic algorithm.

cryptanalysis

The kind of hash function needed for security applications is referred to as a ________________ hash function.

cryptographic

A ___________ is an algorithm for which it is computationally infeasible to find either (a) a data object that maps to a pre-specified hash result or (b) two data objects that map to the same hash result.

cryptographic hash function

The principal object of a hash function is __________ .

data integrity

The hash value of a message in the ____________ _________ application is encrypted with a user's private key.

digital signature

(t/f) The cryptographic hash function is not a versatile cryptographic algorithm.

f

A ___________ accepts a variable length block of data as input and produces a fixed size hash value h = H(M).

hash function

A message authentication code is also known as a _______ hash function.

keyed

An ideal hash algorithm will require a cryptanalytic effort __________ the brute-force effort.

less than

When a hash function is used to provide message authentication, the hash function value is often referred to as a ____________ ______________.

message digest

Requirements for a cryptographic hash function include ____________ which is the one-way property.

preimage

The cryptographic hash function requirement that guarantees that it is impossible to find an alternative message with the same hash value as a given message and prevents forgery when an encrypted hash code is used is the ___________ .

second pre-image resistant

The ___________________ resistant guarantees that it is impossible to find an alternative message with the same hash value as a given message.

second preimage

The compression function used in secure hash algorithms falls into one of two categories: a function specifically designed for the hash function or an algorithm based on a ___________________________.

symmetric block cipher

(t/f) A good hash function has the property that the results of applying the function to a large set of inputs will produce outputs that are evenly distributed and apparently random.

t

(t/f) A weak hash function is sufficient to protect against an attack in which one party generates a message for another party to sign.

t

(t/f) Hash functions are commonly used to create a one-way password file.

t

(t/f) Hash functions can be used for intrusion and virus detection.

t

(t/f) It is possible to use a hash function but no encryption for message authentication.

t

(t/f) The SHA-512 algorithm has the property that every bit of the hash code is a function of every bit of the input.

t

(t/f) The way to measure the resistance of a hash algorithm to cryptanalysis is to compare its strength to the effort required for a brute-force attack.

t

(t/f) Virtually all cryptographic hash functions involve the iterative use of a compression function.

t

(t/f) big-endian format is the most significant byte of a word in the low-address byte position.

t

A hash function that satisfies the properties of variable input size, fixed output size, efficiency, preimage resistant and second preimage resistant is referred to as a __________.

weak hash function

SHA-1 produces a hash value of __________ bits.

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