Q. 13 Using public key cryptography, X adds a digital signature M, encrypts < M,s >
, and sends it to Y , where it is decrypted. Which one of the following sequences
of keys is used for the operations?
(A) Encryption: X’s private key followed by Y ’s private key;
Decryption: X’s public key followed by Y ’s public key
(B) Encryption: X’s private key followed by Y ’s public key;
Decryption: X’s public key followed by Y ’s private key
(C) Encryption: X’s public key followed by Y ’s private key;
Decryption: Y ’s public key followed by X’s private key
(D) Encryption: X’s private key followed by Y ’s public key;
Decryption: Y ’s private key followed by X’s public key
Answer: (D)
Explanation:
