What is the formula used for decoding the ciphered text using affine cipher(a,b are constants and x is the numerical equivalent of a letter to be encrypted)? 1. (a^-1) (x-b)%26 2. (ax+b)%26 3. (b^-1)(x-a)%26 4. (b^-1)(x-a)

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

What is the formula used for encryption of data using affine cipher(a,b are constants and x is the numerical equivalent of a letter to be encrypted)? 1. ax+b 2. (ax+b)%26 3. a(x^2) +bx 4. (a(x^2) +bx)%26

] You receive a message that was encrypted using the RSA system with public key (43, 143), where 43 is the public exponent. A message encrypted using this cryptosystem was captured by an enemy and consisted of the following numbers: 6 82 132 115. Can you decipher what was the original message?      (Hint: As a first step, you need to find p and q.)