In this article, we show you how to use Java Cryptography Extension (JCE) to encrypt or decrypt a text via Data Encryption Standard (DES) mechanism.
1. DES Key
Create a DES Key.
KeyGenerator keygenerator = KeyGenerator.getInstance("DES");
SecretKey myDesKey = keygenerator.generateKey();
2. Cipher Info
Create a Cipher instance from Cipher class, specify the following information and separated by a slash (/).
- Algorithm name
- Mode (optional)
- Padding scheme (optional)
Cipher desCipher;
// Create the cipher
desCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
Note
DES = Data Encryption Standard.
ECB = Electronic Codebook mode.
PKCS5Padding = PKCS #5-style padding.
DES = Data Encryption Standard.
ECB = Electronic Codebook mode.
PKCS5Padding = PKCS #5-style padding.
In this case, you created a DES (Data Encryption Standard) cipher in Electronic Codebook mode, with PKCS #5-style padding.
3. Convert It
Convert String into Byte[] array format.
byte[] text = "No body can see me".getBytes();
4. Encrypt It
Make Cipher in encrypt mode, and encrypt it with Cipher.doFinal() method.
desCipher.init(Cipher.ENCRYPT_MODE, myDesKey);
byte[] textEncrypted = desCipher.doFinal(text);
5. Decrypt It
Make Cipher in decrypt mode, and decrypt it with Cipher.doFinal() method as well.
desCipher.init(Cipher.DECRYPT_MODE, myDesKey);
byte[] textDecrypted = desCipher.doFinal(textEncrypted);
6. Full Example
Full Example to show how to use Java’s JCE to encrypt and decrypt text in DES mechanism.
package com.mkyong.util;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
public class JEncrytion
{
public static void main(String[] argv) {
try{
KeyGenerator keygenerator = KeyGenerator.getInstance("DES");
SecretKey myDesKey = keygenerator.generateKey();
Cipher desCipher;
// Create the cipher
desCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
// Initialize the cipher for encryption
desCipher.init(Cipher.ENCRYPT_MODE, myDesKey);
//sensitive information
byte[] text = "No body can see me".getBytes();
System.out.println("Text [Byte Format] : " + text);
System.out.println("Text : " + new String(text));
// Encrypt the text
byte[] textEncrypted = desCipher.doFinal(text);
System.out.println("Text Encryted : " + textEncrypted);
// Initialize the same cipher for decryption
desCipher.init(Cipher.DECRYPT_MODE, myDesKey);
// Decrypt the text
byte[] textDecrypted = desCipher.doFinal(textEncrypted);
System.out.println("Text Decryted : " + new String(textDecrypted));
}catch(NoSuchAlgorithmException e){
e.printStackTrace();
}catch(NoSuchPaddingException e){
e.printStackTrace();
}catch(InvalidKeyException e){
e.printStackTrace();
}catch(IllegalBlockSizeException e){
e.printStackTrace();
}catch(BadPaddingException e){
e.printStackTrace();
}
}
}
Output
Text [Byte Format] : [B@19b5393
Text : No body can see me
Text Encryted : [B@4e79f1
Text Decryted : No body can see me
Reference
- JavaTM Cryptography Architecture – http://java.sun.com/j2se/1.5.0/docs/guide/security/CryptoSpec.html
Cipher is not thread-safe. Is there any solution to use the Cipher (with single instance) in a multi-threading environment apart from synchronized block.
Superb
Not useful with Updated Java version. Kindly update your tutorial.
What if I want the user to enter their own key while encryption and use that key to decrypt?
Really helpful thanks 🙂
while i am gone decrypt the string i got following exception :
Exception : while decryption : javax.crypto.BadPaddingException: Given final block not properly padded
Simple and cool
Keep it up!
what type of algorithm did you use ?
Thanks a lot for the article. Can you please tell how I can save and then restore generated key? I need to save it in file or hardcoded constant.
I’ve just found an answer. )
// save key
byte[] key = myDesKey.getEncoded();
// restore key
myDesKey = new SecretKeySpec(key, “DES”);
Hi, thanks for your sample code.
I’m not sure what if I would like to change key, if I change this
KeyGenerator.getInstance(“DES”);
to this
KeyGenerator.getInstance(“ThisIsMyKey”);
Is that right way to use my own key ?
Thank you~
@mkyoung
This example gives encrypt and decrypt using standards.
I have to encrypt using public certificate and decrypt using private certificate.
Will you be able to provide sample fo the above?
nice post.. but i got error javax.crypto.IllegalBlockSizeException: last block incomplete in decryption
javax.crypto.IllegalBlockSizeException: last block incomplete in decryption
Hi nice post, but i need separate method encryption and decryption but i got error like “javax.crypto.IllegalBlockSizeException: last block incomplete in decryption” pl.help on this
it s veryusefull
it’s vey usefull….. thanks lot
I need to know how to do encyption at the server side (JAX-rs service). well, i was able to do but the size of the byte is getting increased from 128 to 638 due to which i am unable to decrypt. Pls help me in this regard
This program is excellent. Now I came to know why Java is so powerful. Thanks…..
this post was vary helpful.. thank you
Thanks for information, can l reguest your program complete?
because theprogram important for me to help mystudy.
thank you very much….
Complete example is provided in article above.
Sir,
Can you help me to this code with user input like user can give a secret key or can input a message?
I’m trying but its not working. So, please if you help me to overcome from this, I’m very respectful to you.
Thankful
Thank you for this post. Very helpful information.
pretty cool!
This Example is so helpful to me.can u give some example or link which are provided by another third party tool used in java or more effextive than this java cryptography….do u think this is enough for data security.