Encrypting data using my own key

[Balasubramaniam Muthusamy]

Hello Everyone,
I have a database with the following fields

Name, id, and salary.

And let say there are 100 people can extract the above data from my database. Here I would like to encrypt the data using my own key and write the unreadable format data to output file.

Also if somepoint later, user wants to decrypt to data to view, I should be able to decrypt the data.

Could you please someone share me if you have any sample code?

Thanks
Bala

[Ulf Dittmer]

Start reading up on the JCE API: https://coderanch.com/how-to/java/SecurityFaq#encryption. A cipher like AES-128 would be suitable.

[Balasubramaniam Muthusamy]

Thank you so much for your reply. Just I happened to see your reply today. I gone thorugh the code and I have created the sample program as well. is the any way we can avoid special characters in the encoded output? is there any way the output can only be restricted to data type specific?

Your help would be really appreciated and it will help me a lot.

Thanks
Bala

[Ulf Dittmer]

Just to be precise: the data is *encrypted*, not *encoded*. As such it is binary, not text - so it doesn't have any "characters" in it, and can't be treated as text (or stored as a String). If you need to treat it as text, then you need to encode the ciphertext using something like base-64 encoding.

[Balasubramaniam Muthusamy]

Thanks for the correction. Could you please show me any sample program? I am getting the text only not binary format

Thanks
Bala

[Ulf Dittmer]

I am getting the text only not binary format

What do you mean by that? Encryption normally hands you a byte[] - that is the binary data. base-64 encoding can be done with a library such as Apache Commons Codec.

[Balasubramaniam Muthusamy]

Here is my sample java code and output as below. In the encrypted output I should not have any special character. It should have only alphanumeric. And another thing is possible to get output length as specified by us? Thank you for your help


Before Encryption : Testing encryption
After Encryption : 5Mpp1Vwej3jfnyck99F0u0UaqxUkNH4ky3Z9BbxlvUA=
After Decryption : Testing encryption

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class JcaTest {
	private Cipher ecipher;
	private Cipher dcipher;

	JcaTest(SecretKey key) {
		try {
			ecipher = Cipher.getInstance("AES");
			dcipher = Cipher.getInstance("AES");
			ecipher.init(Cipher.ENCRYPT_MODE, key);
			dcipher.init(Cipher.DECRYPT_MODE, key);
		} catch (Exception e) {
			System.out.println("Failed in initialization");
		}
	}

	public String encrypt(String str) {
		try {
			byte[] utf8 = str.getBytes("UTF-8");
			byte[] enc = ecipher.doFinal(utf8);
			
			return new sun.misc.BASE64Encoder().encode(enc);
		} catch (Exception e) {
			System.out.println("Failed in Encryption");
		}
		return null;
	}

	public String decrypt(String str) {
		try {
			byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

			byte[] utf8 = dcipher.doFinal(dec);

			return new String(utf8, "UTF-8");
		} catch (Exception e) {
			System.out.println("Failed in Decryption");
		}
		return null;
	}

	public static void main(String[] args) {
		try {
			String mykey ="1234567891234567";
			SecretKey key = new SecretKeySpec(mykey.getBytes(), "AES");
			JcaTest encrypter = new JcaTest(key);
		    String original = "Testing encryption";
		    System.out.println("Before Encryption   : " + original);
			String encrypted = encrypter.encrypt(original);
			System.out.println("After Encryption   : " + encrypted);
		    String decrypted = encrypter.decrypt(encrypted);
		    System.out.println("After Decryption   : " + decrypted);
		
		    
		    
		} catch (Exception e) {
		}


	}
}

[Jesper de Jong]

Balasubramaniam Muthusamy wrote:Here is my sample java code and output as below. In the encrypted output I should not have any special character. It should have only alphanumeric.

When you use Base64 encoding, as you are doing, you will not get only alphanumeric characters (i.e. characters in the ranges A-Z, a-z and 0-9); you might also get characters like '='. If you don't want that, then use some other encoding algorithm instead of Base64, that only produces alphanumeric characters.

Note also that catching exceptions and doing nothing with them, as you do in lines 59 - 60, is a bad idea. If an exception happens, you'll never know.

Also, it's not a good idea to use internal Sun classes, such as sun.misc.BASE64Encoder and sun.misc.BASE64Decoder. These classes are not part of Java's public API and they might not exist on all JVM implementations, or they might not even exist in a future version of Oracle's JVM implementation. If you do need to use Base64 encoding, then use a third-party library with a supported API instead, for example Apache Commons Codec.

[Balasubramaniam Muthusamy]

Thank you much for your good guidelines. I have not captured the exception as it is for simply testing purpose. Going forward i will avoid in testing classes as well.

As far base64 concern i will use default API as you said and will try to do some workaround. I will let you know once i find something.

Thanks for your invaluable time.
Bala

[TIMUS ANARUHK]

Bala,
Were you able to do this? It can be done by using a Base32 encoder as well? What did you use?
Thanks.