Multiple encryption is a technique in which an encryption algorithm is used multiple times. In the first instance, plaintext is converted to ciphertext using the encryption algorithm. This ciphertext is then used as input and the algorithm is applied again. This process may be repeated through any number of stages.

Chapter
6 **BLOCK CIPHER OPERATION**

**
****Multiple Encryption and
Triple DES**

Double DES

Triple DES with Two Keys Triple DES with Three Keys

**
****Electronic
Code Book**

**
****Cipher Block Chaining Mode**

**
****Cipher Feedback Mode**

**
****Output Feedback
Mode**

**
****Counter Mode**

**
****XTS-AES Mode for Block-Oriented Storage Devices**

Storage Encryption Requirements Operation on a Single Block Operation on
a Sector

KEY POINTS

◆ Multiple encryption is a technique in
which an encryption algorithm is used multiple times. In the first instance,
plaintext is converted to ciphertext using the encryption algorithm. This
ciphertext is then used as input and the algorithm is applied again. This
process may be repeated through any number of stages.

◆ Triple DES makes use of three stages of
the DES algorithm, using a total of two or three distinct keys.

◆ A mode of operation is a technique for
enhancing the effect of a crypto- graphic algorithm or adapting the algorithm
for an application, such as applying a block cipher to a sequence of data
blocks or a data stream.

◆ Five modes of operation have been
standardized by NIST for use with symmetric block ciphers such as DES and AES:
electronic codebook mode, cipher block chaining mode, cipher feedback mode,
output feed- back mode, and counter mode.

◆ Another important mode, XTS-AES, has been
standardized by the IEEE Security in Storage Working Group (P1619). The
standard describes a method of encryption for data stored in sector-based
devices where the threat model includes possible access to stored data by the
adversary.

This chapter continues our discussion of symmetric
ciphers. We begin with the topic of multiple encryption, looking in particular at the most widely used multiple-encryption
scheme: triple DES.

The chapter next turns to the subject
of block cipher
modes of operation.We find that there are a number of different
ways to apply a block cipher to plaintext, each with its own
advantages and
particular applications.

Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail

Cryptography and Network Security Principles and Practice : One Symmetric Ciphers : Block Cipher Operation : Block Cipher Operation |

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