Assignment:
Prove that the RSA Cryptosystem is insecure against a chosen ciphertext attack: Given a ciphertext y, describe how to choose a ciphertexty(hat) ≠ y such that the knowledge of the plaintextx(hat)=dk (y(hat) )allows you to compute x=dk (y). Hint: First prove that in the RSA Cryptosystem,ek (x1 ) ek (x2 )modn=ek (x1 x2 modn).
Provide complete and step by step solution for the question and show calculations and use formulas.