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Unformatted text preview: 23 21 5 10 Convert the result back to English letters to obtain ciphertext x v f k Now lets reverse the operation to compute the plaintext x from the ciphertext y Start with the ciphertext============================================ x v f k Convert ciphertext English to numeric equivalent (range 0-25) to get y 23 21 5 10 Apply the decryption function on the ciphertext by first computing y-b, that is, y-5 18 16 5 Now multiply the result by the inverse of a which is a-1 = 9 162 144 45 Now apply mod(m) = mod(26) on the values to get the plaintext 6 14 19 Convert the result back to English letters to obtain the plaintext G O A T CS172/283 Class 2 Affine Cipher Example 20090908 Page 1...
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This document was uploaded on 12/05/2009.
- Spring '09
- Computer Security