Cryptography Advantages And Disadvantages

Cryptography can be described as the study of mathematical techniques associated with the security of transmission and storage of information. Cryptography is a main tool in today's information security, and although it has been historically linked to confidentiality, modern cryptography addresses also the issues of integrity, authentication and non-repudiation. Fundamentally, there are two types of cryptography: symmetric-key cryptography and public-key cryptography. Symmetric-key (or secret-key) cryptography can be seen as an outgrowth of classical cryptography [1]. If users want to securely communicate with each other, they must share a key, which is beneficial to both encrypt and decrypt messages [1]. The security of a symmetric-key scheme

trusted courier). When considering a network of users wishing to communicate securely, every pair of users must share a secret key, which makes it impractical for any medium-size network. A solution could involve a central entity, which would be trusted by all the users (e.g. a trusted third party) and whose job would be the issuance of ephemeral session keys. There are a number of other solutions, but it should be clear that key establishment is one of the main problems.

The concept of public-key cryptography was proposed in 1976 [2]. As explained in the work, the main motivation for this new concept was to “minimize the need for secure key distribution channels and supply the equivalent of a written signature”. In public key cryptography each user has a key pair (e, d), which consists of a public key “e” and private key “d”. The user A can make “e” publicly available and keep “d” secret. Now anyone can encrypt information with “e”, while only “A” can decrypt it with “d”. Alternatively, the private key can be used to sign a document, and anyone can use the corresponding public key to

However, where complexity theory is, roughly speaking, about exploring and quantifying this distinction, cryptography is about exploiting it. More specifically, cryptography is the study of constructions where some of the computations involved are deliberately easy, while others are deliberately hard. Having defined the vague terms “easy” and “hard”, the goal is to prove that the hard computations are indeed hard. To establish precise lower bounds on hard computations, but complexity theorists have had limited success in establishing lower bounds in general, so instead of reason relatively: it shows that the hard computations are at least as hard as solving some problem known or assumed (usually the latter, for reasons to be explained in due course) to be hard [5]. The proof technique for making assertions about the complexity of one problem on the basis of another is called “reduction”, where 1) at this stage very informally, 2) a reduction from a problem P to a problem Q amounts to constructing a program that uses a given or postulated solution to Q to solve