To ensure message integrity, confidentiality and non repudiation between two parties, the MOST effective
method would be to create a message digest by applying a cryptographic hashing algorithm against:

A.
the entire message, enciphering the message digest using the sender’s private key, enciphering the
message with a symmetric key and enciphering the key by using the receiver’s public key.

B.
any part of the message, enciphering the message digest using the sender’s
private key, enciphering the message with a symmetric key and enciphering the key using the receiver’s
public key.

C.
the entire message, enciphering the message digest using the sender’s private key, enciphering the
message with a symmetric key and enciphering both the encrypted message and digest using the receiver’s
public key.

D.
the entire message, enciphering the message digest using the sender’s private key and enciphering the
message using the receiver’s public key.

Explanation:
Applying a cryptographic hashing algorithm against the entire message addresses the message integrity issue.
Enciphering the message digest using the sender’s private key addresses non repudiation. Encrypting the
message with a symmetric key, thereafter allowing the key to be enciphered using the receiver’s public key,
most efficiently addresses the confidentiality of the message as well as the receiver’s non repudiation. The
other choices would address only a portion of the requirements.