What Is Block Cipher?
This section describes what is block cipher - An encryption scheme in which 'the clear text is broken up into blocks of fixed length, and encrypted one block at a time'.
Block Cipher - An encryption scheme that "the clear text is broken up into blocks
of fixed length, and encrypted one block at a time".
Usually, a block cipher encrypts a block of clear text into a block of cipher text
of the same length. In this case, a block cipher can be viewed as a simple substitute
cipher with character size equal to the block size.
ECB Operation Mode - Blocks of clear text are encrypted independently.
ECB stands for Electronic Code Book. Main properties of this mode:
- Identical clear text blocks are encrypted to identical cipher text blocks.
- Re-ordering clear text blocks results in re-ordering cipher text blocks.
- An encryption error affects only the block where it occurs.
CBC Operation Mode - The previous cipher text block is XORed with
the clear text block before applying the encryption mapping. Main properties of
- An encryption error affects only the block where is occurs and one next block.
Product Cipher - An encryption scheme that "uses multiple ciphers
in which the cipher text of one cipher is used as the clear text of
the next cipher". Usually, substitution ciphers and transposition ciphers are used
alternatively to construct a product cipher.
Iterated Block Cipher - A block cipher that "iterates a fixed number of times
of another block cipher, called round function, with a different key, called round key,
for each iteration".
Feistel Cipher - An iterate block cipher that uses the following algorithm:
T: 2t bits of clear text
k1, k2, ..., kr: r round keys
f: a block cipher with bock size of t
C: 2t bits of cipher text
(L0, R0) = T, dividing T in two t-bit parts
(L1, R1) = (R0, L0 XOR f(R0, k1))
(L2, R2) = (R1, L1 XOR f(R1, k2))
C = (Rr, Lr), swapping the two parts
Last update: 2015.
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
PHP Implementation of DES - mcrypt
►Blowfish - 8-Byte Block Cipher
►What Is Block Cipher?
Blowfish Cipher Algorithm
Key Schedule (Sub-Keys Generation) Algorithm
BlowfishJ - Java Implementation by Markus Hahn
Blowfish Decryption Algorithm
First 8336 Hex Digits of PI
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