Which of the following hash functions contains demonstrated collision vulnerabilities and is not considered secure? a. SHA-256 b. SHA-512 c. MD2 d. MD4 5. Grace would like to send a message to Joe...

Which of the following hash functions contains demonstrated collision vulnerabilities and is not considered secure? a. SHA-256 b. SHA-512 c. MD2 d. MD4 5. Grace would like to send a message to Joe using digital signature technology. What portion of the message should she sign in order to obtain the digital signature? a. The plaintext message b. The ciphertext message c. The plaintext message digest d. The ciphertext message digest