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

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Key generators are constructed using one of the getInstance class methods of this class. KeyGenerator objects are reusable, i.e., after a key has been generated, the same KeyGenerator object can be re-used to generate further keys. There are two ways to generate a key: in an algorithm-independent manner, and in an algorithm-specific manner. Java Cryptography Extension (JCE) provides framework and implementation for generating key and encryption/decryption of data using various algorithms. In this tutorial, we will use Java DES implementation to encrypt and decrypt a file. DES is a block cipher algorithm in which we will have to use same key for encryption and decryption. The licence key problem is easy, decide on HOW the licence key will be checked, for example summing the digits adds up to 93, then write a simple function to generate them. Personally, I use a hash code from the registration details, e.g. The user's email. To make an exe is not trivial. Jun 09, 2012  Simple Implementation of SDES Algorithm in Java. GitHub Gist: instantly share code, notes, and snippets. The first argument must be -e, -d, or -g to encrypt,. decrypt, or generate a key. The second argument is the name of a file. from which the key is read or to which it is written for -g. The -e and.d arguments cause the program to read from standard input and encrypt or. decrypt to standard output. I am reading over a slide that I found online regarding the DES algorithm for encryption and I am a little confused about the per round key generation. From the slide below, I understand that each per round key is obtained by shifting left either 1 or 2 bits depending on the round.

SDES - Simplified DES. Similar properties and structure but with much smaller parameters than DES. As in DES, the initial and final permutations, which are fixed and independent of the key, provide no real security benefit, but make the algorithm slow if implemented in software.

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:

This class provides the functionality of a secret (symmetric) key generator.

Key generators are constructed using one of the getInstanceUsed to generate an encryption key. class methods of this class.

KeyGenerator objects are reusable, i.e., after a key has been generated, the same KeyGenerator object can be re-used to generate further keys.

There are two ways to generate a key: in an algorithm-independent manner, and in an algorithm-specific manner. The only difference between the two is the initialization of the object:

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• Algorithm-Independent Initialization

  All key generators share the concepts of a keysize and a source of randomness. There is an init method in this KeyGenerator class that takes these two universally shared types of arguments. There is also one that takes just a keysize argument, and uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness (or a system-provided source of randomness if none of the installed providers supply a SecureRandom implementation), and one that takes just a source of randomness.

  Since no other parameters are specified when you call the above algorithm-independent init methods, it is up to the provider what to do about the algorithm-specific parameters (if any) to be associated with each of the keys.

• Algorithm-Specific Initialization

  For situations where a set of algorithm-specific parameters already exists, there are two init methods that have an AlgorithmParameterSpec argument. One also has a SecureRandom argument, while the other uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness (or a system-provided source of randomness if none of the installed providers supply a SecureRandom implementation).

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In case the client does not explicitly initialize the KeyGenerator (via a call to an init method), each provider must supply (and document) a default initialization.

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Every implementation of the Java platform is required to support the following standard KeyGenerator algorithms with the keysizes in parentheses:

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• AES (128)
• DES (56)
• DESede (168)
• HmacSHA1
• HmacSHA256

Des Key Generation Program In Java Free

These algorithms are described in the KeyGenerator section of the Java Cryptography Architecture Standard Algorithm Name Documentation. Consult the release documentation for your implementation to see if any other algorithms are supported.