[a] Suppose that an integer x has the digits a, b, c, d such that: x= 1000*a+100*b+10*c+d Calculate x mod 9 in terms of a, b, c, d ? [2 Points] [b] Consider the following 1-bit key stream generator for a stream cipher where LFSR 1, LFSR 2 and LFSR 3 represent three Linear Feedback Shift Registers (LFSRs) with L, L2, and L3 flip-flops, respectively. 11 LFSR 1 LFSR 2 -keystream LFSR 3 Assume that (x1, x2, x3) = (1, 0, 1) and the sender would like to send a stream plaintext p of value 1, what will be the ciphertext stream? Show your steps in the solution? [2 Points] [c] Let p=11, q=3, e=3 for user X using RSA algorithm. 1. Compute the private key of the sender. [2 Points] 2. Some other user would like to send a message M=7 for user X What will be the ciphertext that user X receives? [2 Points] [a] A message of 1024 bits to be encrypted using DES algorithm with Counter Mode (CTR). If the DES algorithm takes te seconds to encrypt a block. What is the total time (in terms of te) required to encrypt the entire message using a parallel computer? Justify your answer. [2 Points) [a] Suppose that an integer x has the digits a, b, c, d such that: x= 1000*a+100*b+10*c+d Calculate x mod 9 in terms of a, b, c, d ? [2 Points] [b] Consider the following 1-bit key stream generator for a stream cipher where LFSR 1, LFSR 2 and LFSR 3 represent three Linear Feedback Shift Registers (LFSRs) with L, L2, and L3 flip-flops, respectively. 11 LFSR 1 LFSR 2 -keystream LFSR 3 Assume that (x1, x2, x3) = (1, 0, 1) and the sender would like to send a stream plaintext p of value 1, what will be the ciphertext stream? Show your steps in the solution? [2 Points] [c] Let p=11, q=3, e=3 for user X using RSA algorithm. 1. Compute the private key of the sender. [2 Points] 2. Some other user would like to send a message M=7 for user X What will be the ciphertext that user X receives? [2 Points] [a] A message of 1024 bits to be encrypted using DES algorithm with Counter Mode (CTR). If the DES algorithm takes te seconds to encrypt a block. What is the total time (in terms of te) required to encrypt the entire message using a parallel computer? Justify your answer. [2 Points)