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Encrypting/Decrypting String using Symmetric Key Java code example - Click here to copy ->>>
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// -----------------------------------------------------------------------------
// StringEncrypter.java
// -----------------------------------------------------------------------------
/*
* =============================================================================
* Copyright (c) 1998-2005 Jeffrey M. Hunter. All rights reserved.
*
* All source code and material located at the Internet address of
* http://www.idevelopment.info is the copyright of Jeffrey M. Hunter, 2005 and
* is protected under copyright laws of the United States. This source code may
* not be hosted on any other site without my express, prior, written
* permission. Application to host any of the material elsewhere can be made by
* contacting me at jhunter@idevelopment.info.
*
* I have made every effort and taken great care in making sure that the source
* code and other content included on my web site is technically accurate, but I
* disclaim any and all responsibility for any loss, damage or destruction of
* data or any other property which may arise from relying on it. I will in no
* case be liable for any monetary damages arising from such loss, damage or
* destruction.
*
* As with any code, ensure to test this code in a development environment
* before attempting to run it in production.
* =============================================================================
*/
// CIPHER / GENERATORS
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.KeyGenerator;
// KEY SPECIFICATIONS
import java.security.spec.KeySpec;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEParameterSpec;
// EXCEPTIONS
import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.InvalidKeyException;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;
import java.io.UnsupportedEncodingException;
import java.io.IOException;
/**
* -----------------------------------------------------------------------------
* The following example implements a class for encrypting and decrypting
* strings using several Cipher algorithms. The class is created with a key and
* can be used repeatedly to encrypt and decrypt strings using that key.
* Some of the more popular algorithms are:
* Blowfish
* DES
* DESede
* PBEWithMD5AndDES
* PBEWithMD5AndTripleDES
* TripleDES
*
* @version 1.0
* @author Jeffrey M. Hunter (jhunter@idevelopment.info)
* @author http://www.idevelopment.info
* -----------------------------------------------------------------------------
*/
public class StringEncrypter {
Cipher ecipher;
Cipher dcipher;
/**
* Constructor used to create this object. Responsible for setting
* and initializing this object's encrypter and decrypter Chipher instances
* given a Secret Key and algorithm.
* @param key Secret Key used to initialize both the encrypter and
* decrypter instances.
* @param algorithm Which algorithm to use for creating the encrypter and
* decrypter instances.
*/
StringEncrypter(SecretKey key, String algorithm) {
try {
ecipher = Cipher.getInstance(algorithm);
dcipher = Cipher.getInstance(algorithm);
ecipher.init(Cipher.ENCRYPT_MODE, key);
dcipher.init(Cipher.DECRYPT_MODE, key);
} catch (NoSuchPaddingException e) {
System.out.println("EXCEPTION: NoSuchPaddingException");
} catch (NoSuchAlgorithmException e) {
System.out.println("EXCEPTION: NoSuchAlgorithmException");
} catch (InvalidKeyException e) {
System.out.println("EXCEPTION: InvalidKeyException");
}
}
/**
* Constructor used to create this object. Responsible for setting
* and initializing this object's encrypter and decrypter Chipher instances
* given a Pass Phrase and algorithm.
* @param passPhrase Pass Phrase used to initialize both the encrypter and
* decrypter instances.
*/
StringEncrypter(String passPhrase) {
// 8-bytes Salt
byte[] salt = {
(byte)0xA9, (byte)0x9B, (byte)0xC8, (byte)0x32,
(byte)0x56, (byte)0x34, (byte)0xE3, (byte)0x03
};
// Iteration count
int iterationCount = 19;
try {
KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
ecipher = Cipher.getInstance(key.getAlgorithm());
dcipher = Cipher.getInstance(key.getAlgorithm());
// Prepare the parameters to the cipthers
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
} catch (InvalidAlgorithmParameterException e) {
System.out.println("EXCEPTION: InvalidAlgorithmParameterException");
} catch (InvalidKeySpecException e) {
System.out.println("EXCEPTION: InvalidKeySpecException");
} catch (NoSuchPaddingException e) {
System.out.println("EXCEPTION: NoSuchPaddingException");
} catch (NoSuchAlgorithmException e) {
System.out.println("EXCEPTION: NoSuchAlgorithmException");
} catch (InvalidKeyException e) {
System.out.println("EXCEPTION: InvalidKeyException");
}
}
/**
* Takes a single String as an argument and returns an Encrypted version
* of that String.
* @param str String to be encrypted
* @return <code>String</code> Encrypted version of the provided String
*/
public String encrypt(String str) {
try {
// Encode the string into bytes using utf-8
byte[] utf8 = str.getBytes("UTF8");
// Encrypt
byte[] enc = ecipher.doFinal(utf8);
// Encode bytes to base64 to get a string
return new sun.misc.BASE64Encoder().encode(enc);
} catch (BadPaddingException e) {
} catch (IllegalBlockSizeException e) {
} catch (UnsupportedEncodingException e) {
} catch (IOException e) {
}
return null;
}
/**
* Takes a encrypted String as an argument, decrypts and returns the
* decrypted String.
* @param str Encrypted String to be decrypted
* @return <code>String</code> Decrypted version of the provided String
*/
public String decrypt(String str) {
try {
// Decode base64 to get bytes
byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);
// Decrypt
byte[] utf8 = dcipher.doFinal(dec);
// Decode using utf-8
return new String(utf8, "UTF8");
} catch (BadPaddingException e) {
} catch (IllegalBlockSizeException e) {
} catch (UnsupportedEncodingException e) {
} catch (IOException e) {
}
return null;
}
/**
* The following method is used for testing the String Encrypter class.
* This method is responsible for encrypting and decrypting a sample
* String using several symmetric temporary Secret Keys.
*/
public static void testUsingSecretKey() {
try {
System.out.println();
System.out.println("+----------------------------------------+");
System.out.println("| -- Test Using Secret Key Method -- |");
System.out.println("+----------------------------------------+");
System.out.println();
String secretString = "Attack at dawn!";
// Generate a temporary key for this example. In practice, you would
// save this key somewhere. Keep in mind that you can also use a
// Pass Phrase.
SecretKey desKey = KeyGenerator.getInstance("DES").generateKey();
SecretKey blowfishKey = KeyGenerator.getInstance("Blowfish").generateKey();
SecretKey desedeKey = KeyGenerator.getInstance("DESede").generateKey();
// Create encrypter/decrypter class
StringEncrypter desEncrypter = new StringEncrypter(desKey, desKey.getAlgorithm());
StringEncrypter blowfishEncrypter = new StringEncrypter(blowfishKey, blowfishKey.getAlgorithm());
StringEncrypter desedeEncrypter = new StringEncrypter(desedeKey, desedeKey.getAlgorithm());
// Encrypt the string
String desEncrypted = desEncrypter.encrypt(secretString);
String blowfishEncrypted = blowfishEncrypter.encrypt(secretString);
String desedeEncrypted = desedeEncrypter.encrypt(secretString);
// Decrypt the string
String desDecrypted = desEncrypter.decrypt(desEncrypted);
String blowfishDecrypted = blowfishEncrypter.decrypt(blowfishEncrypted);
String desedeDecrypted = desedeEncrypter.decrypt(desedeEncrypted);
// Print out values
System.out.println(desKey.getAlgorithm() + " Encryption algorithm");
System.out.println(" Original String : " + secretString);
System.out.println(" Encrypted String : " + desEncrypted);
System.out.println(" Decrypted String : " + desDecrypted);
System.out.println();
System.out.println(blowfishKey.getAlgorithm() + " Encryption algorithm");
System.out.println(" Original String : " + secretString);
System.out.println(" Encrypted String : " + blowfishEncrypted);
System.out.println(" Decrypted String : " + blowfishDecrypted);
System.out.println();
System.out.println(desedeKey.getAlgorithm() + " Encryption algorithm");
System.out.println(" Original String : " + secretString);
System.out.println(" Encrypted String : " + desedeEncrypted);
System.out.println(" Decrypted String : " + desedeDecrypted);
System.out.println();
} catch (NoSuchAlgorithmException e) {
}
}
/**
* The following method is used for testing the String Encrypter class.
* This method is responsible for encrypting and decrypting a sample
* String using using a Pass Phrase.
*/
public static void testUsingPassPhrase() {
System.out.println();
System.out.println("+----------------------------------------+");
System.out.println("| -- Test Using Pass Phrase Method -- |");
System.out.println("+----------------------------------------+");
System.out.println();
String secretString = "Attack at dawn!";
String passPhrase = "My Pass Phrase";
// Create encrypter/decrypter class
StringEncrypter desEncrypter = new StringEncrypter(passPhrase);
// Encrypt the string
String desEncrypted = desEncrypter.encrypt(secretString);
// Decrypt the string
String desDecrypted = desEncrypter.decrypt(desEncrypted);
// Print out values
System.out.println("PBEWithMD5AndDES Encryption algorithm");
System.out.println(" Original String : " + secretString);
System.out.println(" Encrypted String : " + desEncrypted);
System.out.println(" Decrypted String : " + desDecrypted);
System.out.println();
}
/**
* Sole entry point to the class and application used for testing the
* String Encrypter class.
* @param args Array of String arguments.
*/
public static void main(String[] args) {
testUsingSecretKey();
testUsingPassPhrase();
}
}
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References.
The list of classes which were used on this page you can find below. The
links to Java API contain official SUN documentation about all used classes.
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