Which of the following is a correct statement concerning a cryptography system?
a) Because common key cryptography uses different keys for both the sender and receiver, it ensures a high level of confidentiality.
b) Common key cryptography uses different keys for each sender and receiver, key management will become difficult as the number of senders and receivers increases.
c) When encrypting messages using public key cryptography , key management become easier by disclosing a decryption key
d) In the case of public key cryptography , the key used for signatures can be disclosed.