Public Key Cryptography — Test 1

Correct Answer: B. B. Private key and public key
Explanation: In asymmetric key cryptography, each user needs to have 2 keys; one is public and another one is private key. Public key is used for encryption, private is used for decryption.

Correct Answer: A. A. Rivest, shamir, aldleman
Explanation: RSA algorithm is a public key algorithm, which was discovered at M.I.T in 1978. It is very strong but the only disadvantage is, it requires more key length in order to provide more security.

Correct Answer: D. D. Knapsack algorithm
Explanation: Knapsack is the first public key algorithm, that was not that much secured and now it is not in use. Knapsack is the founding algorithm for further algorithms in public key cryptography.

Correct Answer: C. C. Public key can be same for number of users
Explanation: There will be a unique public key for every user, who publishes it. Public key prevents spoofing, by acting as the receiver. Sender uses the public key of the receiver to encrypt the message and the receiver will decrypt the message with his secret key.

Correct Answer: A. A. Rsa, eigamal, elliptic curve cryptography
Explanation: RSA is the initial one and it achieves security using factoring of huge numbers. EIGamal uses numbers module p to strengthen the algorithm. Elliptic curve scheme uses discrete logarithms to achieve security.

Correct Answer: B. B. Lengthy keys are required for more security
Explanation: RSA schemes need at least 1024 bits in a key for providing good level of security. Symmetric key cryptography uses 128 bits. The more the key length, more the security in RSA, this is why RSA slows down the system.

Correct Answer: D. D. Rsa
Explanation: RSA is named with the first letters of the discoverers (Rivest, Shamir, Aldleman). It uses lengthy keys for security and uses the concept of factoring large numbers to be secured.

Correct Answer: C. C. Key length is larger than rsa
Explanation: Elliptic curve cryptography is much faster and efficient than RSA algorithm. And keys are smaller in size, which are generated by elliptic curve equation.

Correct Answer: D. D. Used to decrypt small messages
Explanation: Public key cryptography cannot deal well with bulk messages. It uses very lengthy keys compared to symmetric key cryptography; this makes the system slow to proceed with bulk messages.

Correct Answer: A. A. True
Explanation: A sender can make use of pubic directory to acquire the public key of the recipient. After acquiring the public key of the receiver, sender will encrypt the message using receiver public key. If sender encrypts the message with his own secret key, then only the sender can decrypt it.