![]() Show how Oscar can break the affine cipher by using two pairs of plaintext–ciphertext, (x1, y1) and (x2, y2). In an attack scenario, we assume that the attacker Oscar manages somehow to provide Alice with a few pieces of plaintext that she encrypts. From which village does the plaintext come?Īnswer = Hobbiton ( The Hobbit and Lord of The Rings, by J.R.R. The following ciphertext was encrypted using the key (a = 17,b = 1). Key space = (#values for a) * (#values for b) = 8 * 30 = 240ģ. How large is the key space of the affine cipher for this alphabet? What are the encryption and decryption equations for the cipher? E(x) = (ax + b) mod 30 D(x) = c(x - b) mod 30Ģ. The German alphabet consists of the English one together with the three umlauts, A, ¨ O, ¨ U, and the ¨(even stranger) “double s” character ß.ġ. ![]() 1.4.4 such that we can encrypt and decrypt messages written with the full German alphabet. ![]() Now, we want to extend the affine cipher from Sect. Decrypt the text: falszztysyjzyjkywjrztyjztyynaryjkyswarztyegyyjĪnswer = firstthesentenceandthentheevidencesaidthequeenġ.12. ![]() From pages 26-27 of Understanding Cryptography, by Christof Paar & Jan Pelzlġ. ![]()
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