Nonprobabilistic RSA means that the same sequence of plaintext letters maps to the same ciphertext. This allows traffic analysis (i.e., to draw some conclusion about the cleartext by merely observing the ciphertext) and in some cases even to the total break of the cryptosystem. The latter holds especially if the number of possible plaintexts is small. Suppose the following situation: Alice wants to send a message to Bob encrypted with his public key pair (n,e). Therefore, she decides to use the ASCII table to assign a number to each character (Space ? 32, ! ? 33, . . . , A ? 65, B ? 66, . . . , ~? 126) and to encrypt them separately.
i. Oscar eavesdrops on the transferred ciphertext. Describe how he can successfully decrypt the message by exploiting the nonprobabilistic property of RSA.