Encryption And Decryption Using DESede ( Triple DES algorithm Padding modes ) In Java?

There are several ways to do Encryption And Decryption but here i am going to use DESede ( Triple DES algorithm Padding modes ) found in namespace called  javax.crypto.Cipher.  javax.crypto.Cipher Class provides the  functionality of a cryptographic cipher for encryption and decryption.

While creating the Cipher object,we need to pass  requested transformation to  Cipher's getInstance method. A transformation always includes the name of a cryptographic algorithm (e.g., DES), and may be followed by a feedback mode and padding scheme.

A transformation is of the form:

1. "algorithm/mode/padding" or

2.  "algorithm"

For example, the following is a valid transformation:

Cipher c = Cipher.getInstance("DES/CBC/PKCS5Padding");

Here is the Compete Code:

package desencryptor;

import java.security.GeneralSecurityException;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class Main {

//NOTES: KEY MUST BE 32 OR 48 CHAR.
//IT CAN BE 16, BUT REPEAT FIRST 16 TO MAKE IT 32.
private static final String KEY="981AFA8CDEB2A0F7E0A011B557BB08CF";
private static final String ALGORITHM = "DESede";
private static final String CIPHER_PARAMETERS = "DESede/CBC/PKCS5Padding";

private static final byte[] HEX_EIGHT_ZEROS = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
private static final char[] HEXTAB = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
private static final byte[] KEY_BYTES = new byte[24];
private static final IvParameterSpec ivSpec1 = new IvParameterSpec(HEX_EIGHT_ZEROS);

private static String strFinalKey = KEY;
static {
if (strFinalKey.length() == 32) {
strFinalKey = strFinalKey.concat(strFinalKey.substring(0, 16));
}
}
private static final String KEY_LOWER = strFinalKey.toLowerCase();

static{
init();
}

public Main() {
}

private static void init(){
Main objSelf = new Main();
objSelf.binHexToBytes(KEY_LOWER, KEY_BYTES, 0, KEY_BYTES.length);
}

public String encrypt(String strNormalPassword) {
String strEncryptedPassword = null;
byte[] bytesFormatOfPassword = strNormalPassword.getBytes();
try {
if (binHexToBytes(KEY_LOWER, KEY_BYTES, 0, KEY_BYTES.length) != (KEY_BYTES.length)) {
}
SecretKey desEdeKey = new SecretKeySpec(KEY_BYTES, ALGORITHM);

Cipher desEdeCipher = Cipher.getInstance(CIPHER_PARAMETERS);
desEdeCipher.init(Cipher.ENCRYPT_MODE, desEdeKey, ivSpec1);
byte[] cipherText = desEdeCipher.doFinal(bytesFormatOfPassword);
strEncryptedPassword = bytesToBinHex(cipherText, 0, cipherText.length);
} catch (GeneralSecurityException gse) {
gse.printStackTrace();
} catch (Exception ae) {
ae.printStackTrace();
}
return strEncryptedPassword;
}

public String decrypt(String strEncryptedPassword){
String strPassLowerCase = strEncryptedPassword.toLowerCase();
String strDecryptedPassword = null;
byte[] cipherBytes = new byte[strPassLowerCase.length() / 2];
try {
int intBinToHaxByteCount = binHexToBytes(strPassLowerCase, cipherBytes, 0, strPassLowerCase.length() / 2);
if (intBinToHaxByteCount != (strEncryptedPassword.length() / 2)) {

}
SecretKey desEdeKey = new SecretKeySpec(KEY_BYTES, ALGORITHM);

Cipher desEdeCipher = Cipher.getInstance(CIPHER_PARAMETERS);
desEdeCipher.init(Cipher.DECRYPT_MODE, desEdeKey, ivSpec1);
byte[] plainText = desEdeCipher.doFinal(cipherBytes);
strDecryptedPassword = new String(plainText, 0, plainText.length);
} catch (GeneralSecurityException gse) {
gse.printStackTrace();
} catch (Exception ae) {
ae.printStackTrace();
}
return strDecryptedPassword;
}

private int binHexToBytes(String sBinHex, byte[] data, int nSrcPos, int nNumOfBytes) {
// Dest pos set to zero.
int nDstPos = 0;
// check for correct ranges
int nStrLen = sBinHex.length();
int nAvailBytes = (nStrLen - nSrcPos) >> 1;
if (nAvailBytes < nNumOfBytes) {
nNumOfBytes = nAvailBytes;
}
int nOutputCapacity = data.length;
if (nNumOfBytes > nOutputCapacity) {
nNumOfBytes = nOutputCapacity;
}
// convert now
int nResult = 0;
for (int nI = 0; nI < nNumOfBytes; nI++) {
byte bActByte = 0;
boolean blConvertOK = true;
for (int nJ = 0; nJ < 2; nJ++) {
bActByte <<= 4;
char cActChar = sBinHex.charAt(nSrcPos++);

if ((cActChar >= 'a') && (cActChar <= 'f')) {
bActByte |= (byte) (cActChar - 'a') + 10;
} else if ((cActChar >= 'A') && (cActChar <= 'F')) {
bActByte |= (byte) (cActChar - 'A') + 10;
} else {
if ((cActChar >= '0') && (cActChar <= '9')) {
bActByte |= (byte) (cActChar - '0');
} else {
blConvertOK = false;
}
}
}
if (blConvertOK) {
data[nDstPos++] = bActByte;
nResult++;
}
}
return nResult;
}

private String bytesToBinHex(byte[] data, int nStartPos, int nNumOfBytes) {
StringBuffer sbuf = new StringBuffer();
sbuf.setLength(nNumOfBytes << 1);

int nPos = 0;
for (int nI = 0; nI < nNumOfBytes; nI++) {
sbuf.setCharAt(nPos++, HEXTAB[(data[nI + nStartPos] >> 4) & 0x0f]);
sbuf.setCharAt(nPos++, HEXTAB[data[nI + nStartPos] & 0x0f]);
}
return sbuf.toString();
}

public static void main(String[] args) {
Main dd = new Main();
String inputText = "abcdef";
System.out.println(" Original Text : "+inputText);
String encyptedText = dd.encrypt(inputText);
String decyptedText = dd.decrypt(encyptedText);
System.out.println(" Encypted Text : "+encyptedText);
System.out.println(" Decypted Text : "+decyptedText);
}
}

Reference:

1. http://docs.oracle.com/javase/7/docs/api/javax/crypto/Cipher.html

To download the complete source code, please click on the following link.
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