A.ICMP session

B.UDP first packet session

C.Self-session to the firewall

D.TCP half-connection session

A.After receiving A's encrypted information, B uses his own private key to open the digital envelope and obtains the symmetric key

B.A uses B's public key to encrypt the symmetric key and generate a digital envelope.

C.A sends the digital envelope and ciphertext information to B.

D.A uses the symmetric key to encrypt the plain text and generate cipher text information.

E.B uses the symmetric key to decrypt the ciphertext information and obtains the original plaintext

A.The PKI entity supports sending a certificate registration request message to the CA through the SCEP protocol to apply for a local certificate.

B.When the certificate expires and the key is leaked, the PKI entity must replace the certificate. The certificate can be updated by re-applying, or it can be updated automatically using the SCEP or CMPv2 protocol.

C.Normally, a PKI entity will generate a pair of public and private keys. The public key and its own identity information are sent to the CA to generate a local certificate.

D.PKI can only apply for local certificates online, which has a high security factor.

A.True

B.False