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Cryptanalysis of RSA Factorization - Library(ISI Kolkata) - Indian ...

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Chapter 1<br />

Introduction<br />

The word ‘Cryptology’ originates from the Greek root words ‘kryptós’ (hidden)<br />

and ‘logia’ (study). So, quite literally, cryptology is the study and practice <strong>of</strong><br />

hiding information, that is, the art and science <strong>of</strong> information security. It is quite<br />

natural that the notion <strong>of</strong> security requires the presence <strong>of</strong> an adversary, and any<br />

system must be tested against all potential attacks. Based on this idea, cryptology<br />

has been branched into two parts - Cryptography and <strong>Cryptanalysis</strong>. While<br />

cryptography ensures secure communication between two parties over insecure<br />

communication channels (telephone, courier, fax, e-mail etc.), the field <strong>of</strong> cryptanalysis<br />

deals with the study <strong>of</strong> breaking a cryptographic scheme by obtaining the<br />

classified information without authorization.<br />

Cryptology was used vastly in ancient civilizations throughout the world.<br />

Around 3000 BC, the Egyptians could communicate securely by writing messages<br />

in the coded Hieroglyph. ‘Artha-Sastra’ by the renowned <strong>Indian</strong> politician Kautilya<br />

(350–283 BC) discussed the use <strong>of</strong> cryptology in political circles. Julius<br />

Caesar (100–44 BC) used the Caesar cipher to send confidential messages.<br />

The subject resurrected and evolved in a completely new form at the dawn <strong>of</strong><br />

the modern information era. During World War II, cryptology gained much more<br />

importance in political affairs. It was the famous episode <strong>of</strong> Enigma that made the<br />

worldaware<strong>of</strong>thepotentialpower<strong>of</strong>thesubject. Today, cryptologyhasearnedits<br />

repute as a prime branch <strong>of</strong> modern science that deals with information security<br />

issues in the arena <strong>of</strong> digital globalization. It is used for numerous purposes <strong>of</strong><br />

everyday life, including Internet banking, identification cards, secure databases,<br />

e-mails, social networking, and many more.<br />

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