Java Program for DES Encryption

by J. Orlin Grabbe

The program listed below, testDES.java:

In this example, we see see the following three numbers:

Java Source Code

testDES.java

import java.io.*;
import java.security.*;
import java.math.*;
import cryptix.util.core.BI;
import cryptix.util.core.ArrayUtil;
import cryptix.util.core.Hex;
import cryptix.provider.key.*;


class testDES {

public static void main (String[] args) {

	try {
	FileOutputStream outFile1 = new FileOutputStream("DES.out");
	// Note: PrintStream is deprecated, but still works fine in jdk1.1.7b
	PrintStream output1 = new PrintStream(outFile1);

	// convert a string to a DES key and print out the result
	RawSecretKey key2 = new RawSecretKey("DES",Hex.fromString("3812A419C63BE771"));
	RawKey rkey = (RawKey) key2;
	byte[] yval = rkey.getEncoded();
	BigInteger Bkey = new BigInteger(yval);
	String w = cryptix.util.core.BI.dumpString(Bkey);
	output1.println("The Encryption Key = " + w);
	
	// use the DES key to encrypt a string
	Cipher des=Cipher.getInstance("DES/ECB/NONE","Cryptix");
	des.initEncrypt(key2);	
	byte[] ciphertext = des.crypt(Hex.fromString("01010101010101010102030405060708090A0B0C0D0E0F101112131415161718"));

	// print out length and representation of ciphertext 
	output1.print("\n");
	output1.println("ciphertext.length = " + ciphertext.length);

	BigInteger Bciph = new BigInteger(ciphertext);
	w = cryptix.util.core.BI.dumpString(Bciph);
	output1.println("Ciphertext for DES encryption = " + w);
	
	// decrypt ciphertext 
	des.initDecrypt(key2);
	ciphertext = des.crypt(ciphertext);
	output1.print("\n");
	output1.println("plaintext.length = " + ciphertext.length);

	// print out representation of decrypted ciphertext 
	Bciph = new BigInteger(ciphertext);
	w = cryptix.util.core.BI.dumpString(Bciph);
	output1.println("Plaintext for DES encryption = " + w);

	output1.println(" ");
	output1.close();		

      } catch (Exception e) {
            System.err.println("Caught exception " + e.toString());
      }

	}}

Sample Program Output

DES.out

The Encryption Key = Multi-Precision Integer 62 bits long...
      sign: Positive
 magnitude: 3812A419C63BE771 

ciphertext.length = 32
Ciphertext for DES encryption = Multi-Precision Integer 254 bits long...
      sign: Positive
 magnitude: 3A2EAD12F475D82C 1FC97BB9A6D955E1 EA5541946BB4F2E6 F29555A6E8F1FB3C 

plaintext.length = 32
Plaintext for DES encryption = Multi-Precision Integer 249 bits long...
      sign: Positive
 magnitude: 0101010101010101 0102030405060708 090A0B0C0D0E0F10 1112131415161718 

J. Orlin Grabbe is the author of International Financial Markets, and is an internationally recognized derivatives expert who has recently branched out into cryptology, banking security, and digital cash. His home page is located at http://www.aci.net/kalliste/homepage.html. He currently resides in Costa Rica.