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1. Key Generator For Games
2. Des 16 Key Generator Java Pdf
3. Des 16 Key Generator Java Free

The following are top voted examples for showing how to use javax.crypto.SecretKey.These examples are extracted from open source projects. You can vote up the examples you like and your votes will be used in our system to generate more good examples. Algorithm described later in the chapter. Figure 6.2 shows the elements of DES cipher at the encryption site. 56-bit cipher key 48-bit 48-bit 48-bit 64-bit plaintext DES 64-bit ciphertext K 1 K 2 K 16 Initial permutation Round 1 Final permutation Round 2 Round 16 Round-key generator Fig. 6.2 General structure of DES.

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The Data Encryption Standard (DES) is a symmetric-key block cipher published by the National Institute of Standards and Technology (NIST).

DES is an implementation of a Feistel Cipher. It uses 16 round Feistel structure. The block size is 64-bit. Though, key length is 64-bit, DES has an effective key length of 56 bits, since 8 of the 64 bits of the key are not used by the encryption algorithm (function as check bits only). General Structure of DES is depicted in the following illustration −

Since DES is based on the Feistel Cipher, all that is required to specify DES is −

• Round function
• Key schedule
• Any additional processing − Initial and final permutation

Initial and Final Permutation

The initial and final permutations are straight Permutation boxes (P-boxes) that are inverses of each other. They have no cryptography significance in DES. The initial and final permutations are shown as follows −

Round Function

The heart of this cipher is the DES function, f. The DES function applies a 48-bit key to the rightmost 32 bits to produce a 32-bit output.

• Expansion Permutation Box − Since right input is 32-bit and round key is a 48-bit, we first need to expand right input to 48 bits. Permutation logic is graphically depicted in the following illustration −

• The graphically depicted permutation logic is generally described as table in DES specification illustrated as shown −

• XOR (Whitener). − After the expansion permutation, DES does XOR operation on the expanded right section and the round key. The round key is used only in this operation.

• Substitution Boxes. − The S-boxes carry out the real mixing (confusion). DES uses 8 S-boxes, each with a 6-bit input and a 4-bit output. Refer the following illustration −

• The S-box rule is illustrated below −

• There are a total of eight S-box tables. The output of all eight s-boxes is then combined in to 32 bit section.

• Straight Permutation − The 32 bit output of S-boxes is then subjected to the straight permutation with rule shown in the following illustration:

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. These two properties make cipher very strong.

• Avalanche effect − A small change in plaintext results in the very great change in the ciphertext.

• Completeness − Each bit of ciphertext depends on many bits of plaintext.

During the last few years, cryptanalysis have found some weaknesses in DES when key selected are weak keys. These keys shall be avoided.

DES has proved to be a very well designed block cipher. There have been no significant cryptanalytic attacks on DES other than exhaustive key search.

Multiple implementations of DES (Data Encryption Standard) encryption anddecryption. Includes the following:

• des.py

  Straightforward but slow. Well documented and easy to follow; a goodlearning tool for people new to DES.

• des.c

  Conversion of des.py into C.

• des_64.c

  Optimized based on techniques described below in the optimizationssection. Useful learning tool to understand these optimizations

• crack/

  Distributed, optimized key search (known plaintext attack). Takes a knownplaintext, ciphertext pair and tries every key until one of them works.More information in /crack/README.rst

All implementations except for crack/ are learning tools for DES andoptimizations. In contrast, crack/ is fully optimized and not meant forreadability, although it is well commented and as readable as it can be withoutsacrificing speed.

The software is licensed under the MIT license (see LICENSE.txt), so you canmodify and reuse this code without any restrictions. If you re-use a largepart of the code, attribution would be nice, but not required.

Contributions are welcome!

des.py

To encrypt, run des.py using Python and pass in your plaintext and key in hex:

Here, beefbeefbeefbeef is the plaintext and 0123456789abcdef is thekey. They both must be 16 hex digits.

Key Generator For Games

To decrypt, use the -d option and give ciphertext instead of plaintext:

ASCII Input/Output

If you want to give the plaintext with 8 ASCII characters, use the -a option:

When decrypting, -a will instead convert the resulting plaintext into ASCII:

Verbose Output

You can also use the -v option to have it show detailed step by stepcalculations:

Use this for your homework!

des.c and des_64.c

You will need GNU Make and gcc. To compile, run make:

This will create executables des and des_64.

For now, there is no way to provide input on the command line. Sorry, it's inthe TODO list. You will have to put the input in the code yourself. Currentlydes and des_64 are set up to run many encryptions as a speed test.

Optimizations

These optimizations were proposed by Eli Biham in the paper 'A Fast New DESImplementation in Software'.

64-Bit Parallel

This is a way to do 64 encryptions simultaneously utilizing 64-bit integers.

Consider the normal way to do 64 encryptions at once. We would store each key,plaintext and ciphertext in an array. Then, every time we do an operation, wedo it to all 64. Now consider how one of these values, the key for example, isstored. They would be stored in an array like this:

Des 16 Key Generator Java Pdf

Bit 1	Bit 2	Bit 3	Bit 4	Bit 5	..
int64 Key 1	a	b	c	d	e	..
int64 Key 2	f	g	h	i	j	..
int64 Key 3	k	l	m	n	o	..
int64 Key 4	p	q	r	s	t	..
int64 Key 5	u	v	w	x	y	..
..	..	..	..	..	..	..

Des 16 Key Generator Java Free

Normal Format

Each row contains a key. We can store each key as a 64-bit integer, so wewould have an array of 64 integers. /origin-cd-key-generator-2014.html. Now suppose we transpose the table above:

Key 1	Key 2	Key 3	Key 4	Key 5	..
int64 Bit 1	a	f	k	p	u	..
int64 Bit 2	b	g	l	q	v	..
int64 Bit 3	c	h	m	r	w	..
int64 Bit 4	d	i	n	s	x	..
int64 Bit 5	e	j	o	t	y	..
..	..	..	..	..	..	..

Zipped Format

We store each row in a 64-bit integer, again giving us an array of 64 integers.We call this zipped format. Now instead of looping through each of the 64parallel encryptions to do an operation, we can just do the operation on one64-bit integer. For example, Doing an xor with two elements of arrays in thisformat, a single xor instruction will simultaneously do an xor for all 64encryptions.

When you see functions like zip_64_bit in the code, these convert from normalto zipped format. Since this is like transposing a matrix, zip_64_bit is itsown inverse.

Permutation Elimination

Permutations are expensive and DES requires a lot of them. But we don'tactually have to permute things in memory in order to compute the result.Instead, we can index the bit that would be used if the permutation wereactually performed. Biham explains this as 'changing the naming of theregisters.' This includes the expansion step as well.

This is best explained by example. Consider this pseudocode:

It's pretty obvious the swap is unnecessary:

Eliminating permutations is the same idea on a larger scale.

Bitwise S-Boxes

Traditionally, s-boxes are implemented with lookup tables. But s-boxes canactually be implemented using nothing but logic gate operations, which is muchfaster, especially when using the 64-bit parallel optimization.

Finding the optimum logic design of s-boxes is very non-trivial. A Eli Bihamtalks about this in his paper 'A Fast New DES Implementation in Software', butMatthew Kwan's page entitled bitslicehas much more up to date information, as well as some history.

The fastest implementation I know about is implemented in John the Ripper. They actually havemultiple implementations, and the fastest one is automatically chosen.

This project's bitwise DES s-box implementation can be found ininclude/sbox.h, which defines functions s0 through s7. I didn't come upwith any designs myself.