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.

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 ...

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