Indicate the true statements from the statements given below. 1. Alice and Bob use public key cryptography to send messages, and they mutually trust a certificate authority (CA). Bob obtains a certificate that indicates his public key and is signed by CA's public key. Alice can verify the certificate and confidently use Bob's public key indicated in the certificate.
2. Alice and Bob use public key cryptography to send messages. Suppose Alice received a plaintext message m with a digital signature. To verify that m is not modified in transit, Alice will (1) apply Bob's public key to retrieve the message digest that Bob computed, (2) apply the hash function to m, and (3) verifies that the two digests match.
3. Alice and Bob do not need to a priori shared secret keys to use symmetric key cryptography since they can create one for each session using RSA publick key cryptography.
4. Alice and Bob use public key cryptography to send messages confidentially. A message sent by Alice to Bob is confidential if Alice encrypts it with her private key and sends the resulting ciphertext to Bob.
5. Alice and Bob use public key cryptography to send messages. If Alice wants to send a message m with a digital signature, then to create the digital signature, Alice applies a hash function and encrypts the message digest with Bob's private key.
6. Alice and Bob use public key cryptography to send messages. For confidentiality and authenticity, Alice should encrypt the message using her private key, encrypt the result with Bob's public key, and send the result to Bob.
7. Nonces are used to protect the integrity of the messages sent.
8. Alice and Bob must have been assigned a shared secret key priori to using sending confidential messages using symmetric key cryptography.
9. Alice and Bob use public key cryptography and do not have any a priori shared secret keys. Suppose, Alice (1) computes the message digest and encrypts it using her private key, (2) encrypts the message and the encrypted digest with a newly generated secrect key and a symmetric key cryptography technique, (3) encrypts the secret key with Bob's public key, and sends the items from steps 2 and 3 to Bob. This ensures message confidentiality, integrity, and authenticity.
10. Alice and Bob use public key cryptography to send messages. The authenticity of a message sent by Alice to Bob can be verified if Alice encrypts it using her public key and sends the ciphertext to Bob.