Introducting DES Stream Cipher Modes
This section describes what are DES encryption stream cipher modes and how CFB and OFB block operation modes can be modified as stream modes.
As we know from previous tutorials, DES algorithm is a block cipher algorithm. But it can be operated
in different ways to become stream ciphers.
(FIPS 81) Federal Information Processing Standards Publication 81 published in 1980 defined the following
4 operation modes:
- 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 FIPS 81, the last two operation modes, CFB and OFB, are defined in ways so that they can be used as
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.
E(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.
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 in Stream Cipher Modes
►Introducting DES Stream Cipher Modes
CFB (Cipher FeedBack) as a Stream Cipher
OFB (Output FeedBack) as a Stream Cipher
CFB and OFB Stream Ciphers Implemented in JCE
JCE DES Stream Ciphers Testing Program
JCE DES Stream Ciphers Testing Program Result
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