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Using public key cryptography, X adds a digital signature σ to a message M, encrypts (M,σ) and sends it to Y, where it is decrypted. Which one of the following sequence of keys is used for 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 private key followed by Y’s public key; Decryption : Y’s private key followed by X’s public key.
(D) Encryption : X’s public key followed by Y’s private key; Decryption : Y’s public key followed by X’s private key.
nan