AO A B C D E F G H I J K L M 0 1 2 3 4 5 6 7 8 9 10 11 12 N 0 P Q R S T U V W X Y Z 13 14 15 16 17 18 19 20 21 22 23 24 25 (Show your work.) Encrypt the message "TYVQ" using Affine Cipher in English alphabet with a = 7; b =22 and encryption function is f(p) = (7p+22) mod 26 A) hens B) helo C) zine D) zict

Encrypt The following correspondence between letters and numbers is used in the Caesar cypher. a b d e f i k lm n o r u V W X y z 1 2 3 4 6 7 8 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Encrypt the animal name zebra with the Caesar cypher with a key of 25. What is the encrypted animal name (enter a string of letters with no spaces)? Save Submit You have used 0 of 1 attempt Decrypt An animal name was encrypted with the scheme described above. The encrypted animal name is azmchbnns . What is the animal name? Save

Use symmetric ciphers to encrypt message "“promise" and decrypt message "FOG". The representation of characters in modulo 26 is described as follows: Plaintext - a bcdefg|hijk1 mnopar stuvwx y z Ciphertext A BCD|EFG|HIJKL|M|NO|P|Q|R s T|U|VwxY|Z Value 00 01 02|03 04 05 06|07|08|09|10|11 12|13|14|15 16|17 18|19 20 21 22 23 24 25 The mathematical equations for encryption and decryption can be described as follows: Encryption Ea:i→i+kmod 26 Decryption Da : i→i-k mod 26 i represents the messages (plaintext or cipher), k represents a symmetric key. In this case k=20

A symmetric block encryption algorithm is shown below. 16-bit blocks of plaintext P are encrypted using a 32-bit key. Encryption is defined as: C = (P EX_OR Ko) + K1 C is the ciphertext, K is the secret key, Ko is the leftmost 16 bits of K, K1 is the rightmost 16 bits of K, EX_OR is bitwise exclusive OR, and + is binary addition. a. The ciphertext C must be the same size as the plaintext P, that is, it must not be larger than 16 bits. How can this be achieved? b. Show the decryption equation. How will the encrypted message be decrypted?

Using C programming language: A Transposition Cipher  A very simple transposition cipher encrypt(S, N) can be described by the following rules:  If the length of S is 1 or 2, then encrypt(S, N) is S.  If S is a string of N characters s1 s2 s3... sN and k = N/2, then encrypt(S)= encrypt(sk sk−1... s2 s1 ,K)+ encrypt(sN sN−1... sk+1 ,N - K)  where + indicates string concatenation. For example, encrypt("Ok", 2) = "Ok" and encrypt("12345678", 8) = "34127856".  Write a program to implement this cipher. The input is a file that is guaranteed to have less then 2048 characters. Code structure might look like this: #define MAX_SIZE 2048char text_buffer[MAX_SIZE];int main(){    // read file into text_buffer    encrypt(text_buffer, n);    // print out text_buffer    return 0;}

for letter in encrypt: new_position=(alphabets.find(letter)-key)%len(alphabets) decrypt+=alphabets[new_position] print("Decrypted message:",decrypt) can you explain line by line what each method and function does

Encrypt The following correspondence between letters and numbers is used in the Caesar cypher. a b c d f h i j k lm n t V W e g 6. u y 0 1 2 3 4 7 8. 9. 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Encrypt the animal name zebra with the Caesar cypher with a key of 3. What is the encrypted animal name (enter a string of letters with no spaces)? Decrypt An animal name was encrypted with the scheme described in the previous question (it was encoded with the key 3). The encrypted animal name is pduprw .What is the animal name?

Write Program: encrypt the text by monoalphabetic cipher algorithm key= ['qwertyuiopasdfghjklzxcvbnm'] plain "text ='monoapphabetic cipher

There are other modes of block cipher besides the ones (OFB,CFB,CTR). One of these modes is named Plaintext Block Chaining (PBC) Mode. On the encryption side, the following is executed to obtain the nth ciphertext: Cn := Ek(Mn)XOR Mn-1. Suppose that we need to encrypt M1; : : : ;M5 using the PBC mode. Show the explicit formulas to obtain C1; : : : ;C5. What do you need to use for M0? Also, show the steps on the decryption side to obtain M1; : : : ;M5.

Answer ALL questions. The ciphertext message below was encrypted using affine transformation C = P + k(mod 26),0 ≤ C ≤ 25. YFXMP CESPZC JTDBF PPYZQX LESPX LETND a) By completing the following table, find the most frequently occurring letter in the ciphertext. Letter Number of Occurrence Question (b) is based on the information in tables below and answer in Question (a). A B C 1 2 3 Numerical 0 equivalent Frequency 7 (in %) Letter Numenical equivalent Frequency 8 (in %) N 13 ABCD E FGHIJKLMNOPQRSTUVWXYZ 1 0 14 7 P 15 3 D 4 Q 16 <1 E 13 13 R 17 8 F 5 3 S 18 6 G 2 T 19 9 H L 3 U 20 3 8 V 21 1 JK 9 <1 W 22 10 <1 LM <1 11 4 X Y 23 24 2 12 3 Z 25 <1 The tables show that the most frequently occurring letters in English text are E, T, N, R, I, O and A, with E occurring substantially more than the other letters. b) Determine what is the letter that represents C and P in affine transformation C = P + k(mod 26),0 ≤ C≤ 25. Then, show that the value of k = 11(mod 26). c) What is the plaintext…