Question 1

Message authentication protects two parties who exchange
messages from any third party, however, it does not protect the
two parties against each other.

Accepted Answer

Message authentication ensures that a message has been sent by the purported sender and has not been altered, protecting against third-party tampering, but it does not prevent disputes between the sender and receiver themselves over the content or the fact of the message being sent.

Question 2

the main work for signature generation depends on the message
and is done during the idle time of the processor.

Accepted Answer

The main work for signature generation is typically done at the time of signing and depends on the key used, not the message. The process might utilize idle time for efficiency, but this is not a fundamental characteristic of how digital signatures are generated.

Question 3

the digital signature function does not include the authentication
function.

Accepted Answer

Digital signatures include the authentication function as they verify the identity of the signer and ensure that the message or document has not been altered after signing.

Question 4

Unlike RSA, DSS cannot be used for encryption or key exchange.

Accepted Answer

DSS (Digital Signature Standard) is specifically designed for digital signatures and does not support encryption or key exchange, unlike RSA which can be used for encryption, decryption, and key exchange.

Question 5

__________ is where the attacker forges a signature for a particular message chosen by the attacker.
A)total break
B)Universal forgery
C)Existential forgery
D)Selective forgery

Accepted Answer

Selective forgery is when the attacker forges a signature for a particular message chosen by the attacker.

Question 6

It is important in a direct digital signature to perform an outer
confidentiality function first and then the signature function.

Accepted Answer

In a direct digital signature, the signature function is performed first on the message, and then, if confidentiality is also desired, the result (the message plus its signature) can be encrypted. This ensures that the recipient can verify the signature after decrypting the message.

Question 7

It must be computationally infeasible to forge a digital signature,
either by constructing a new message for an existing digital
signature or by constructing a fraudulent digital signature for a given message.

Accepted Answer

Digital signatures are designed to be secure in such a way that forging them—either by creating a new message to match an existing signature or by generating a fraudulent signature for a given message—is computationally infeasible, ensuring the integrity and authenticity of the signed data.

Question 8

Similar to the generic attack, except that the list of messages to be signed is chosen after the attacker knows the user's public key but before any signatures are seen, is the __________ attack.
A)directed chosen
B)key-only
C)adaptive chosen
D)known message

Accepted Answer

In a directed chosen attack, the attacker selects the messages to be signed after knowing the user's public key but before observing any signatures, making it similar to a generic attack.

Question 9

the first part of the Schnorr digital signature scheme is the
generation of a private/public key pair.

Accepted Answer

In the Schnorr digital signature scheme, the first step involves generating a private/public key pair, which is fundamental for the security and functionality of the scheme.

Question 10

the global public key components of DSA are the same as for the
Schnorr signature scheme.

Accepted Answer

Both the DSA (Digital Signature Algorithm) and the Schnorr signature scheme use similar global public key components, including a prime number, a generator, and a prime order subgroup, which are fundamental in the setup of the cryptographic algorithms for secure key generation and verification processes.

Question 11

A digital signature can guarantee the integrity but not the source of
the message.

Accepted Answer

A digital signature guarantees both the integrity of the message and the identity (source) of the sender, as it uses cryptographic techniques to bind these elements together.

Question 12

the __________ is formed by taking the hash of the message and encrypting the message with the creator's private key.
A)timestamp
B)message digest
C)hash code
D)digital signature

Accepted Answer

A digital signature is created by hashing the message and then encrypting the hash with the creator's private key, ensuring authenticity and integrity.

Question 13

the most important development from the work on public-key
cryptography is the digital signature.

Accepted Answer

Digital signatures, which are a product of public-key cryptography, provide a means to verify the authenticity and integrity of digital messages or documents, making them a crucial development for secure communications and transactions online.

Question 14

the Schnorr signature scheme is based on discrete logarithms.

Accepted Answer

The Schnorr signature scheme is indeed based on the mathematical problem of discrete logarithms, which is a fundamental concept in the field of cryptography.

Question 15

It must be relatively difficult to recognize and verify the digital
signature.

Accepted Answer

Digital signatures are designed to be easily verifiable by the recipient or any third party to ensure the integrity and authenticity of the message or document. Verification processes are typically straightforward, using the signer's public key.

Question 16

With a __________ attack the attacker is given access to a set of messages and their signatures.
A)known message
B)key-only
C)directed chosen message
D)generic chosen message

Accepted Answer

In a known message attack, the attacker has access to a set of messages along with their corresponding signatures. This scenario allows the attacker to analyze the relationship between messages and their signatures without the ability to influence or choose the messages being signed.

Question 17

the global public key components for DSA are p, q, and h.

Accepted Answer

The global public key components for DSA are p, q, and g.

Question 18

the digital signature standard is a __________ standard that uses the secure hash algorithm.
A)IEEE
B)NISt
C)ISO
D)ItIL

Accepted Answer

The Digital Signature Standard (DSS) is a standard by the National Institute of Standards and Technology (NIST) for digital signatures. It uses the Secure Hash Algorithm (SHA) for providing a suite of algorithms for digital signature generation and verification.

Question 19

the ElGamal signature scheme involves the use of the public key
for encryption and the private key for decryption.

Accepted Answer

The ElGamal signature scheme actually involves the use of a private key for signing and a public key for verification, not for encryption and decryption.

Question 20

the DSS approach makes use of a hash function.

Accepted Answer

The DSS (Digital Signature Standard) approach utilizes a hash function as part of its process to generate and verify digital signatures.

Quiz 13: Digital Signatures

Message authentication protects two parties who exchange messages from any third party, however, it does not protect the two parties against each other.

the main work for signature generation depends on the message and is done during the idle time of the processor.

the digital signature function does not include the authentication function.

Unlike RSA, DSS cannot be used for encryption or key exchange.

__________ is where the attacker forges a signature for a particular message chosen by the attacker.

It is important in a direct digital signature to perform an outer confidentiality function first and then the signature function.

It must be computationally infeasible to forge a digital signature, either by constructing a new message for an existing digital signature or by constructing a fraudulent digital signature for a given message.

Similar to the generic attack, except that the list of messages to be signed is chosen after the attacker knows the user's public key but before any signatures are seen, is the __________ attack.

the first part of the Schnorr digital signature scheme is the generation of a private/public key pair.

the global public key components of DSA are the same as for the Schnorr signature scheme.

A digital signature can guarantee the integrity but not the source of the message.

the __________ is formed by taking the hash of the message and encrypting the message with the creator's private key.

the most important development from the work on public-key cryptography is the digital signature.

the Schnorr signature scheme is based on discrete logarithms.

It must be relatively difficult to recognize and verify the digital signature.

With a __________ attack the attacker is given access to a set of messages and their signatures.

the global public key components for DSA are p, q, and h.

the digital signature standard is a __________ standard that uses the secure hash algorithm.

the ElGamal signature scheme involves the use of the public key for encryption and the private key for decryption.

the DSS approach makes use of a hash function.