Basics of Cryptography

The term cryptography is derived from a Greek word that means “hidden.” In computing, cryptography refers to the methods used to “hide,” or secure, communications from unauthorized access. Cryptography is also known as encryption. Encryption is done using established encryption algorithms or procedures. These algorithms may include symmetric, asymmetric, or hashing algorithms. Encryption algorithms further lay the foundation for a PKI, which is one of the widely used methods to secure network communications. This section includes a discussion of important encryption terms, algorithms, and Public Key Infrastructure.


The terms cryptography and encryption are used interchangeably in the following text.

Encryption Algorithms

An algorithm is defined as a procedure or a well-defined set of instructions to accomplish a task when the initial state of the problem is given. In encryption methods, the term encryption algorithm is used to define the process of creating a scrambled or unreadable text (known as cyphertext), from a given readable text (known as plaintext), using the defined procedure. Encryption is used as a protective cover for the data transmitted over network media from one computer to another. Encryption keeps the data secure from unauthorized access by users and by professional hackers. Encryption algorithms lay the foundation for such security mechanisms as confidentiality, authentication, digital signatures, and public key cryptography. They are ...

Get A+, Network+, Security+ Exams in a Nutshell now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.