This exercise exhibits what is called a protocol failure. It provides an exam-ple where ciphertext can be decrypted by an opponent, without determiningthe key, if a cryptosystem is used in a careless way. The moral is that it isnot sufficient to use a "secure" cryptosystem in order to guarantee "secure"communication.Suppose Bob has an RSA Cryptosystem with a large modulus n for whichthe factorization cannot be found in a reasonable amount of time. SupposeAlice sends a message to Bob by representing each alphabetic character asan integer between 0 and 25 (i.e., A ⇒ 0, B ↔ 1, etc.), and then encryptingeach residue modulo 26 as a separate plaintext character.(a) Describe lcrypted in(b) Illustrate this attack by decrypting the following ciphertext (which wasencrypted using an RSA Cryptosystem with n = 18721 and b = 25)without factoring the modulus:365,0, 4845, 14930, 2608, 2608, 0.

(b) Illustrate this attack by decrypting the following ciphertext (which was encrypted using an RSA Cryptosystem with n = 18721 and b = 25) without factoring the modulus: 365,0,4845, 14930, 2608, 2608, 0.

(b) Illustrate this attack by decrypting the following ciphertext (which was encrypted using an RSA Cryptosystem with n = 18721 and b = 25) without factoring the modulus: 365,0,4845, 14930, 2608, 2608, 0.

Advanced Engineering Mathematics

10th Edition

ISBN:9780470458365

Author:Erwin Kreyszig

Publisher:Erwin Kreyszig

Chapter2: Second-order Linear Odes

Section: Chapter Questions

Problem 1RQ

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