# the w 2. This problem explores the use of a one-time pad version of t In…

the w 2. This problem explores the use of a one-time pad version of t In this scheme, the key is a stream of random numbers between 0 and example, if the key is 3 19 5…, then the first letter of plaintext is encrypted with a shift of 3 letters, the second with a shift of 19 letters, the third with a shift of 5 letters, and so on. a. Encrypt the plaintext sendmoremoney with the key stream 9 01 7 23 15 21 14 11 11 28 9 Using the ciphertext produced in part (a), find a key so that the cipher text decrypts to the plaintext cashnotneeded h. 3. Consider the following letter encodings: letter A E|I MOIRIT IV encoding 000 001 010 OI1 100 101 110 111 A message M = MARIO is Vernam encrypted into ciphertext C = A0A1fV: C,-MER, where shows modulo 2 XOR operation. Find the corresponding encryption key. Provide details of your cryptanalaysis. 4. DES Illustration This problem provides a numerical example of encryption using a one-round ver- sion of DES Hexadecimal notation: Binary notation 0123456789ABCDEF 0000 0001 0010 0011 0100 0101 01100111 1000 1001 1010 1011 1100 1101 1110 1111 a. Derive Ki.the first-round subkey b. Derive Lo. Ro Espand R, to get Ewhee i the expansion function of Table S. d. Calculate A-EIRI㊥K, e Group the 48-bit result of (d) into sets of 6 bits and evaluate the corresponding S-box substitutions t Concatenate the results of (e) to get a 32-bit result, B. Apply the permutation to get P(B). h. Calculate Ri-PB) L Write down the ciphertext. The given plain text (in hexadecimal form), P = D2AAF891 CE086587