DES Encryption Operation Mode Introduction
This section describes what are DES encryption operation modes and notations used to describe how each operation mode works.
DES encryption algorithm defines how a single 64-bit plaintext block can be encrypted. It does not define
how a real plaintext message with an arbitrary number of bytes should be padded and arranged into 64-bit input blocks
for the encryption process. It does not define how one input block should be coupled with other blocks from the same
original plaintext message to improve the encryption strength.
(FIPS) Federal Information Processing Standards Publication 81 published in 1980 provided the following block
encryption operation modes to address how blocks of the same plaintext message should be coupled:
- ECB - Electronic Code Book operation mode.
- CBC - Cipher Block Chaining operation mode.
- CFB - Cipher Feedback operation mode
- OFB - Output Feedback operation mode
See http://www.itl.nist.gov/fipspubs/fip81.htm for details.
In order to describe these operation modes, we need to define the following notations:
P = P, P, P, ..., P[i], ... - Representing the original plaintext message, P, being arranged into multiple 64-bit
plaintext blocks. P[i] represents plaintext block number i.
Ek(P[i]) - Representing the DES encryption algorithm applied on a single 64-bit plaintext block, P[i], with a predefined key, k.
C = C, C, C, ..., C[i], ... - Representing the final ciphertext message, C, being regrouped from multiple 64-bit
ciphertext blocks. C[i] represents ciphertext block number i.
IV - Called "Initial Vector", representing a predefined 64-bit initial value.
With these notations, we are ready to describe different operation modes that can be applied the DES encryption algorithm.
Table of Contents
About This Book
Cryptography Basic Concepts
Introduction to AES (Advanced Encryption Standard)
Introduction to DES Algorithm
DES Algorithm - Illustrated with Java Programs
DES Algorithm Java Implementation
DES Algorithm - Java Implementation in JDK JCE
►DES Encryption Operation Modes
►DES Encryption Operation Mode Introduction
What is ECB (Electronic CodeBook) Operation Mode?
What is CBC (Cipher Block Chaining) Operation Mode?
What is CFB (Cipher FeedBack) Operation Mode?
What is OFB (Output FeedBack) Operation Mode?
DES Operation Modes in JCE
JCE DES Operation Mode Testing Program
JCE DES Operation Mode Testing Program Result
DES in Stream Cipher Modes
PHP Implementation of DES - mcrypt
Blowfish - 8-Byte Block Cipher
Secret Key Generation and Management
Cipher - Secret Key Encryption and Decryption
Introduction of RSA Algorithm
RSA Implementation using java.math.BigInteger Class
Introduction of DSA (Digital Signature Algorithm)
Java Default Implementation of DSA
Private key and Public Key Pair Generation
PKCS#8/X.509 Private/Public Encoding Standards
Cipher - Public Key Encryption and Decryption
MD5 Mesasge Digest Algorithm
SHA1 Mesasge Digest Algorithm
OpenSSL Introduction and Installation
OpenSSL Generating and Managing RSA Keys
OpenSSL Managing Certificates
OpenSSL Generating and Signing CSR
OpenSSL Validating Certificate Path
"keytool" and "keystore" from JDK
"OpenSSL" Signing CSR Generated by "keytool"
Migrating Keys from "keystore" to "OpenSSL" Key Files
Certificate X.509 Standard and DER/PEM Formats
Migrating Keys from "OpenSSL" Key Files to "keystore"
Using Certificates in IE (Internet Explorer)
Using Certificates in Firefox
Using Certificates in Google Chrome
PDF Printing Version