Digital Signatures — Test 1

Correct Answer: B. B. Total break
Explanation: Total break is finding private key and Universal forgery is finding signing algorithm. Selective forgery is doing forgery of signature for particular message. Atleast one message can have forgery signature.

Correct Answer: D. D. Computationally feasible
Explanation: If a digital signature is computationally feasible, then it is very easy for a hacker to attack the signing scheme. He may forge the signature for the new message or change the signature for the present message.

Correct Answer: A. A. Source and destination
Explanation: In general, there will be a third party, who authenticate the digital signatures. But there is no rule that everyone should believe the third party. So, the direct digital signature scheme involves sender and receiver. And receiver knows from where the message is coming using public key of the sender.

Correct Answer: A. A. Signature key is of signing and public key for verification
Explanation: In digital signature, private key is the signature key, that is used to create digital signature. And this private key belongs to the signer. Public key belongs to the receiver who receives the message. These two keys are used in digital signature algorithm.

Correct Answer: C. C. Time saving and computationally less expensive
Explanation: RSA uses expressions with exponential, that is modular exponentiation. So, it is difficult to let the large data be signed using modular exponentiation. Hash value of the message is small compared to the whole message. So, it saves time and computation power to use hash to be signed.

Correct Answer: D. D. Security of the message
Explanation: Channel security is not in hands of digital signature, even the secret key is being transmitted between sender and receiver. Security of the message will be depending on the channel that is being used.

Correct Answer: A. A. Ecdsa
Explanation: ECDSA stands for elliptic curve digital signature algorithm. ECDSA has huge acceptance, because it uses small key bit length, elliptic curve cryptography and secured.

Correct Answer: D. D. Sha
Explanation: SHA(secured hash function) is the hash algorithm which uses MD4 hash function. ECDSA, DSA and RSA – PSS are the three algorithms in digital signatures. ECDSA stands for elliptic curve digital signature algorithm, RSA – PSS is probabilistic signature scheme. DSA is digital signature algorithm.

Correct Answer: C. C. 1991
Explanation: After RSA public key algorithm, ElGamal was introduced for digital signatures. But it is claimed by the government, that this algorithm is too slow, insecure, new and secret to meet the cyptographic standards.

Correct Answer: A. A. True
Explanation: Confidentiality function involves receivers public key for encryption, and private key for decryption. The sender cannot deceive the receiver when the digital signature function is inside. Because decryption of the message cannot be done by the sender without receiver’s private key. And the sender cannot change the digital signature.