Криптография

Contents
Introduction 3
1. The history of cryptography 4
2. Basic concepts of cryptography 6
2.1. Subject of cryptography 6
2.2. Cryptographic system model 7
2.3. Formal model and code classification 8
3. Symmetric cryptosystems 9
3.1. Substitution ciphers 9
3.2. Transposition ciphers 10
4. Symmetric cryptosystems 10
4.1. Basics of symmetric cryptosystems 10
4.2. RSA cryptosystems 11
5. Features of asymmetric cryptosystems application 12
Conclusion 12
References 13

Introduction

In modern society, the increasing role is played by the computers, and all electronic means of communication, storage, and processing. To ensure information technology to be used in various fields, it is necessary to ensure its safety and reliability.
Simple encryption techniques appeared a long time ago, but a scientific approach to the study and development of cryptographic methods appeared only in the last (twentieth) century. To date, cryptography contains many fundamental and applied results (theorems and algorithms). Cryptography is impossible without serious mathematical training. Especially knowledge is needed in the field of discrete mathematics, number theory, abstract algebra, and the theory of algorithms. The cryptographic methods are primarily intended for practical use, and strong algorithms can be vulnerable to attacks, not provided by the mathematical model. Therefore, after abstract mathematical model analysis it is always required to analyze the algorithm obtained, considering the situation in which it will be used in practice.
The purpose of this paper is to introduce the basic concepts, methods and objectives of cryptography.
To attain the target, we set the following objectives:
1) to discuss the concepts of cryptography and cryptographic system;
2) to identify the classes that codes are classified with;
3) to examine symmetric and asymmetric cryptosystems;
4) to look into features of asymmetric cryptosystems application.

Conclusion

Summing up the results of our study, it should be noted that it is difficult to reliably protect your secrets. Specialist in any situation expresses doubts about the reliability of protection offered. It is recommended not to show off the algorithm. Even if you were able to prove the theorem that the attacks of your protection system are algorithmically unsolvable, do not relax. Try to understand why the conditions are not met in the case. And finally follow the principle of privacy protection. Having the best security system created, make sure it is protected.