In a Public Key Infrastructure, how are public keys published?

Which of the following service is not provided by a public key infrastructure (PKI)?

What size is an MD5 message digest (hash)?

Which of the following is not a DES mode of operation?

Which of the following offers confidentiality to an e-mail message?

What is the effective key size of DES?

Which fire class can water be most appropriate for?

Which of the following standards concerns digital certificates?

What is the name for a substitution cipher that shifts the alphabet by 13 places?

Which of the following would best describe certificate path validation?