1. Prove that the RSA Cryptosystem is insecure against a chosen ciphertext attack: Given a
ciphertext y, describe how to choose a ciphertext y(hat)≠y such that the knowledge of the
plaintext x(hat)=d_k (y(hat)) allows you to compute x=d_k (y). Hint: First prove that in the RSA
Cryptosystem ,e_k (x_1 ) e_k (x_2 )modn=e_k (x_1 x_2 modn).
We have the cipher text and we want to find its plaintext , such that or . If we choose a specific ...
The expert examines cryptography in RSA.