Jun 10, 2016  Simple C Program For DES Algorithm in Cryptography. Learn how to implement DES algorithm in C programming language. The DES encryption algorithm is an implementation of Fiestel Cipher.There are two different methods enlisted here for DES algorithm implementation in. Key Generation. The round-key generator creates sixteen 48-bit keys out of a 56-bit cipher key. The process of key generation is depicted in the following illustration − The logic for Parity drop, shifting, and Compression P-box is given in the DES description. DES Analysis. The DES satisfies both the desired properties of block cipher. AES 256 Encryption and Decryption in Python. This passphrase is converted to a hash value before using it as the key for encryption. The following program encrypts a sample text and then prints both the encrypted message and decrypted message on the console.

Basic but pure DES implementation in PythonI have written it for fun because nothing else.

How it works ?

Everything is made within a class called 'des'. This class can be instanciated once and used to cipher and decipher multiple datas.It also support padding using the PKCS5 specification. (So the data is padding even if it is multiple of 8 to be sure that the last byte il be padding data).The generation of all the keys used is made in the method generatekeys and substitute apply the SBOX permutation.The main method is run which is called by both encrypt and decrypt but in a different mode. This method do basically all the stuff, it loopthrought all the blocks and for each do the 16th rounds.

Be careful: This module implement DES in ECB mode, so you can't make it weaker. I didn't made it to be strong but for fun.

How to use it ?

I have not done any interface to take argument in command line so this module can't be used as a script. (feel free to modify it).To use it from python shell or in another module do:

Note: In this exemple no padding is specified so you have to provide a text which is multiple of 8 bytes. The key is cut to 8 bytes if longer.

To use padding:

∟Introduction to DES Algorithm

∟DES Key Schedule (Round Keys Generation) Algorithm

This section describes DES (Data Encryption Standard) algorithm - A 16-round Feistel cipher with block size of 64 bits.

Key schedule algorithm:

DES key schedule supporting tables:

Permuted Choice 1 - PC1:

Permuted Choice 2 - PC2:

Left shifts (number of bits to rotate) - r1, r2, ..., r16:

Table of Contents

About This Book

Cryptography Terminology

Cryptography Basic Concepts

Introduction to AES (Advanced Encryption Standard)

►Introduction to DES Algorithm

What Is Block Cipher?

DES (Data Encryption Standard) Cipher Algorithm

►DES Key Schedule (Round Keys Generation) Algorithm

DES Decryption 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

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

Using Certificates in Google Chrome

Using Certificates in Firefox

Outdated Tutorials

Des Key Generation Code In Python 1

References

Des Key Generation Code In Python Pdf

Full Version in PDF/EPUB