CFB and OFB Stream Ciphers Implemented in JCE

This section describes how DES CFB and OFB (Output FeedBack) stream ciphers are implemented in the JDK JCE package.

Sun has implemented stream cipher modes for both CFB and OFB modes, but with restrictions that the feedback sizes must be multiples of 8 bits. To use CFB or OFB in a stream cipher mode, you need to specify the feedback size in bits right after the mode name when calling Cipher.getInstance(algorithm) to create a cipher object like:

   Cipher cObj1 = Cipher.getInstance("DES/CFB8/NoPadding");
   Cipher cObj2 = Cipher.getInstance("DES/CFB16/NoPadding");
   Cipher cObj3 = Cipher.getInstance("DES/CFB24/NoPadding");
   ...
   Cipher cObja = Cipher.getInstance("DES/OFB8/NoPadding");
   Cipher cObjb = Cipher.getInstance("DES/OFB16/NoPadding");
   Cipher cObjc = Cipher.getInstance("DES/OFB24/NoPadding");
   ...

Table of Contents

 About This Book

 Cryptography Terminology

 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

 Outdated Tutorials

 References

 PDF Printing Version