Cryptanalysis of RSA Factorization - Library(ISI Kolkata) - Indian ...
Cryptanalysis of RSA Factorization - Library(ISI Kolkata) - Indian ...
Cryptanalysis of RSA Factorization - Library(ISI Kolkata) - Indian ...
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Chapter 1: Introduction 2<br />
The motive <strong>of</strong> Cryptography, as it stands in the modern society, has broadened<br />
to cover not only encryption and decryption, but all <strong>of</strong> the following categories.<br />
Confidentiality deals with the process <strong>of</strong> encryption and decryption <strong>of</strong> data. This<br />
is the basic goal <strong>of</strong> cryptography that ensures secure data communication<br />
over insecure channels, possibly at the presence <strong>of</strong> a malicious adversary.<br />
DataIntegrity isthemechanismtocheckandmakesurethatthedatahasnotbeen<br />
tampered. This process is important to verify the consistency <strong>of</strong> the data<br />
and make sure no alterations have been made to the original communication.<br />
Authentication ensures proper identification <strong>of</strong> the sender (entity authentication),<br />
and the identification <strong>of</strong> the origin <strong>of</strong> communicated data (data origin authentication).<br />
This feature is required to ensure that data is accepted only<br />
from the authorized senders.<br />
Non-Repudiation is another important aspect <strong>of</strong> cryptography to solve disputes<br />
between the sender and the receiver. It may happen that the sender, after<br />
communicating some data, maliciously claims that he/she has not sent it at<br />
all. Non-repudiation provides the receiver with a pro<strong>of</strong> to refute this claim.<br />
The pro<strong>of</strong> can also be presented to a third-party arbitrator in such a case.<br />
In this thesis, we mainly concentrate on the Confidentiality aspect <strong>of</strong> cryptosystems.<br />
For further details about modern day Cryptology, one may refer to “Cryptography<br />
- Theory and Practice” by D. R. Stinson [126], or “Handbook <strong>of</strong> Applied<br />
Cryptography” by A. J. Menezes, P. C. van Oorschot and S. A. Vanstone [87]. An<br />
interested reader may also refer to “The Code Book” by S. Singh [122] to know<br />
the exciting history <strong>of</strong> evolution <strong>of</strong> the subject.<br />
1.1 Encryption and Decryption<br />
Let us turn our attention to the functional aspect <strong>of</strong> a cryptographic scheme for<br />
confidentiality. In this section, we shall introduce the notions <strong>of</strong> encryption, decryption<br />
and the respective keys associated with these operations.<br />
Suppose Alice wants to send some plaintext M to Bob, and Charles is a malicious<br />
adversary who is eavesdropping on the insecure channel <strong>of</strong> communication.<br />
The scenario is as shown in Figure 1.1. Using some encryption function E, Alice