Question

How do we know the Public Key for a person is turly theirs?

	A.	It decrypts by private key
	B.	It is verified by a Digital Certificate issued by a trusted CA
	C.	The product of the two keys is the original large prime
	D.	All of these

Which of these is true of a public key cipher?

	A.	AES is the current algorithm
	B.	Any number of people can send someone an encrypted message with Public Key, and they can decrypt it with their private key
	C.	A single key is used for both encryption and decryption
	D.	It has been superseded by symmetric key algorithms
	E.	It has been superseded by one-time pad algorithms

Which of theses is a disadvantage of public key cryptography relative to symmetric key cryptography?

	A.	They require two keys instead of just one
	B.	They are slower
	C.	They require larger keys to be secure
	D.	All of these

What bad cryptographic practice got the Soviet Union in trouble during the Cold War?

	A.	Re-using one time cryptographic pads
	B.	Using Outdate cryptographic systems
	C.	None of these
	D.	Lack of awareness of spies being under surveillance.

Which of these is the current reccomended symmetric cryptography algorithm?

	A.	None of these
	B.	Caesar
	C.	DES
	D.	RSA

Answer 1

The answer is B. It is verified by a Digital Certificate issued by a trusted CA.

• Decrypting it with private keys is not true.
• The product of two keys is the original prime number is not a way to identify whether a public key is truly theirs.
• A trusted CA issues a digital certificate and the public key is verified by using that digital certificate.
• So option B is the answer.

Option B is the answer.

• In a public-key cipher, anyone can send a message to someone.
• The public key is known to all.
• So they encrypt with the public key.
• The receiver decrypts that message with its private key.

D.All of the above

• Public key cryptography uses a key for encryption and uses another key for decryption. That is it uses two different keys for encryption and decryption.
• So it needs two keys.
• Symmetric key cryptography uses only a single key for both encryption and decryption.
• So it is a disadvantage of public-key cryptography when compared with symmetric key cryptography.
• Public key cryptography is slower than symmetric key cryptography.
• For security, public-key cryptography needs large keys.
• So it is also a disadvantage.
• So the answer is all of the above.

C. None of these.

• They didn’t reuse one-time cryptographic pads.
• They didn’t use outdated cryptographic systems.
• There wasn’t a lack of awareness of the spies being under surveillance.
• No of these practices were done by the soviet union in the cold war.
• So the answer is none of these.

A.None of these.

• Because AES is the current recommended symmetric cryptography algorithm.
• AES stands for Advanced encryption standard.
• It is not included in the options.
• So None of these is the answer.