Java support many secure encryption algorithms but some of them are weak to be used in security-intensive applications. For example, the Data Encryption Standard (DES) encryption algorithm is considered highly insecure; messages encrypted using DES have been decrypted by brute force within a single day by machines such as the Electronic Frontier Foundation’s (EFF) Deep Crack.
A more secure encryption algorithm is AES – Advanced Encryption Standard which is a symmetric encryption algorithm. AES encryption is used by the U.S. for securing sensitive but unclassified material, so we can say it is enough secure.
Read More : Java AES 256 Encryption Decryption Example
1. AES Encryption and Decryption
Let’s see an example of using AES encryption in this java program.
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.Base64;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
public class AES {
private static SecretKeySpec secretKey;
private static byte[] key;
public static void setKey(final String myKey) {
MessageDigest sha = null;
try {
key = myKey.getBytes("UTF-8");
sha = MessageDigest.getInstance("SHA-1");
key = sha.digest(key);
key = Arrays.copyOf(key, 16);
secretKey = new SecretKeySpec(key, "AES");
} catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
e.printStackTrace();
}
}
public static String encrypt(final String strToEncrypt, final String secret) {
try {
setKey(secret);
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
return Base64.getEncoder()
.encodeToString(cipher.doFinal(strToEncrypt.getBytes("UTF-8")));
} catch (Exception e) {
System.out.println("Error while encrypting: " + e.toString());
}
return null;
}
public static String decrypt(final String strToDecrypt, final String secret) {
try {
setKey(secret);
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, secretKey);
return new String(cipher.doFinal(Base64.getDecoder()
.decode(strToDecrypt)));
} catch (Exception e) {
System.out.println("Error while decrypting: " + e.toString());
}
return null;
}
}
2. Encryption and decryption example
Let’s test if we are able to get the decrypted string back from the encrypted string.
final String secretKey = "ssshhhhhhhhhhh!!!!";
String originalString = "howtodoinjava.com";
String encryptedString = AES.encrypt(originalString, secretKey) ;
String decryptedString = AES.decrypt(encryptedString, secretKey) ;
System.out.println(originalString);
System.out.println(encryptedString);
System.out.println(decryptedString);
Program Output.
howtodoinjava.com
Tg2Nn7wUZOQ6Xc+1lenkZTQ9ZDf9a2/RBRiqJBCIX6o=
howtodoinjava.com
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