forked from TheAlgorithms/Java
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathAESEncryption.java
More file actions
114 lines (105 loc) · 3.78 KB
/
Copy pathAESEncryption.java
File metadata and controls
114 lines (105 loc) · 3.78 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
package ciphers;
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;
import javax.xml.bind.DatatypeConverter;
/**
* This example program shows how AES encryption and decryption can be done in
* Java. Please note that secret key and encrypted text is unreadable binary and
* hence in the following program we display it in hexadecimal format of the
* underlying bytes.
*
*/
public class AESEncryption {
/**
* 1. Generate a plain text for encryption 2. Get a secret key (printed in
* hexadecimal form). In actual use this must by encrypted and kept safe. The
* same key is required for decryption.
*
*/
public static void main(String[] args) throws Exception {
String plainText = "Hello World";
SecretKey secKey = getSecretEncryptionKey();
byte[] cipherText = encryptText(plainText, secKey);
String decryptedText = decryptText(cipherText, secKey);
System.out.println("Original Text:" + plainText);
System.out.println("AES Key (Hex Form):" + bytesToHex(secKey.getEncoded()));
System.out.println("Encrypted Text (Hex Form):" + bytesToHex(cipherText));
System.out.println("Descrypted Text:" + decryptedText);
}
/**
* gets the AES encryption key. In your actual programs, this should be safely
* stored.
*
* @return secKey (Secret key that we encrypt using it)
* @throws NoSuchAlgorithmException
* (from KeyGenrator)
*
*/
public static SecretKey getSecretEncryptionKey() throws NoSuchAlgorithmException {
KeyGenerator aesKeyGenerator = KeyGenerator.getInstance("AES");
aesKeyGenerator.init(128); // The AES key size in number of bits
SecretKey secKey = aesKeyGenerator.generateKey();
return secKey;
}
/**
* Encrypts plainText in AES using the secret key
*
* @param plainText
* @param secKey
* @return byteCipherText (The encrypted text)
* @throws NoSuchPaddingException
* (from Cipher)
* @throws NoSuchAlgorithmException
* (from Cipher)
* @throws InvalidKeyException
* (from Cipher)
* @throws BadPaddingException
* (from Cipher)
* @throws IllegalBlockSizeException
* (from Cipher)
*/
public static byte[] encryptText(String plainText, SecretKey secKey) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
// AES defaults to AES/ECB/PKCS5Padding in Java 7
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE, secKey);
byte[] byteCipherText = aesCipher.doFinal(plainText.getBytes());
return byteCipherText;
}
/**
* Decrypts encrypted byte array using the key used for encryption.
*
* @param byteCipherText
* @param secKey
* @return plainText
* @throws NoSuchPaddingException
* @throws NoSuchAlgorithmException
* @throws InvalidKeyException
* @throws BadPaddingException
* @throws IllegalBlockSizeException
*/
public static String decryptText(byte[] byteCipherText, SecretKey secKey) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
// AES defaults to AES/ECB/PKCS5Padding in Java 7
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.DECRYPT_MODE, secKey);
byte[] bytePlainText = aesCipher.doFinal(byteCipherText);
return new String(bytePlainText);
}
/**
* Convert a binary byte array into readable hex form
*
* @param hash
* (in binary)
* @return hexHash
*/
private static String bytesToHex(byte[] hash) {
return DatatypeConverter.printHexBinary(hash);
}
}