K2XGPtfq

1import java.util.Base64;    
2import javax.crypto.Cipher;  
3import javax.crypto.KeyGenerator;   
4import javax.crypto.SecretKey;  
5public class EncryptionDecryptionAES {  
6    static Cipher cipher;  
7
8    public static void main(String[] args) throws Exception {
9        /* 
10         create key 
11         If we need to generate a new key use a KeyGenerator
12         If we have existing plaintext key use a SecretKeyFactory
13        */ 
14        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
15        keyGenerator.init(128); // block size is 128bits
16        SecretKey secretKey = keyGenerator.generateKey();
17
18        /*
19          Cipher Info
20          Algorithm : for the encryption of electronic data
21          mode of operation : to avoid repeated blocks encrypt to the same values.
22          padding: ensuring messages are the proper length necessary for certain ciphers 
23          mode/padding are not used with stream cyphers.  
24         */
25        cipher = Cipher.getInstance("AES"); //SunJCE provider AES algorithm, mode(optional) and padding schema(optional)  
26
27        String plainText = "AES Symmetric Encryption Decryption";
28        System.out.println("Plain Text Before Encryption: " + plainText);
29
30        String encryptedText = encrypt(plainText, secretKey);
31        System.out.println("Encrypted Text After Encryption: " + encryptedText);
32
33        String decryptedText = decrypt(encryptedText, secretKey);
34        System.out.println("Decrypted Text After Decryption: " + decryptedText);
35    }
36
37    public static String encrypt(String plainText, SecretKey secretKey)
38            throws Exception {
39        byte[] plainTextByte = plainText.getBytes();
40        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
41        byte[] encryptedByte = cipher.doFinal(plainTextByte);
42        Base64.Encoder encoder = Base64.getEncoder();
43        String encryptedText = encoder.encodeToString(encryptedByte);
44        return encryptedText;
45    }
46
47    public static String decrypt(String encryptedText, SecretKey secretKey)
48            throws Exception {
49        Base64.Decoder decoder = Base64.getDecoder();
50        byte[] encryptedTextByte = decoder.decode(encryptedText);
51        cipher.init(Cipher.DECRYPT_MODE, secretKey);
52        byte[] decryptedByte = cipher.doFinal(encryptedTextByte);
53        String decryptedText = new String(decryptedByte);
54        return decryptedText;
55    }
56}