Basic password-based encryption function (for StackOverflow) [684]

!636
!quicknew

import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;

main {
  psvm {
    byte[] data = "hello".getBytes("UTF-8");
    printHex(data);

    Random ranGen = new SecureRandom();
    byte[] salt = new byte[8]; // 8 grains of salt
    ranGen.nextBytes(salt);
    
    String pw = "pw";
    byte[] enc = encrypt(data, pw.toCharArray(), salt);
    printHex(enc);
    System.out.println("enc length: " + enc.length);
    
    byte[] dec = decrypt(enc, pw.toCharArray(), salt);
    System.out.println("decrypted: " + new String(dec, "UTF-8"));
  }
  
  static void printHex(byte[] data) {
    System.out.println(bytesToHex(data));
  }
  
  static String bytesToHex(byte[] bytes) {
    return bytesToHex(bytes, 0, bytes.length);
  }

  static String bytesToHex(byte[] bytes, int ofs, int len) {
    StringBuilder stringBuilder = new StringBuilder(len*2);
    for (int i = 0; i < len; i++) {
      String s = "0" + Integer.toHexString(bytes[ofs+i]);
      stringBuilder.append(s.substring(s.length()-2, s.length()));
    }
    return stringBuilder.toString();
  }

  static SecretKey makeKey(char[] password, byte[] salt) tex {
    /* Derive the key, given password and salt. */
    SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
      
    // only with unlimited strength:
    //KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);
    
    // Let's try this:
    KeySpec spec = new PBEKeySpec(password, salt, 65536, 128);
    
    SecretKey tmp = factory.generateSecret(spec);
    SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
    return secret;
  }
  
  public static byte[] encrypt(byte[] data, char[] password, byte[] salt) {
    try {
      SecretKey secret = makeKey(password, salt);
      
      /* Encrypt the message. */
      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
      cipher.init(Cipher.ENCRYPT_MODE, secret);
      AlgorithmParameters params = cipher.getParameters();
      byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
      new ByteArrayOutputStream baos;
      baos.write(cipher.update(data));
      baos.write(cipher.doFinal());
      byte[] ciphertext = baos.toByteArray();
      return ciphertext;
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  
  static byte[] decrypt(byte[] ciphertext, char[] password, byte[] salt) {
    try {
      SecretKey secret = makeKey(password, salt);
     
      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
      cipher.init(Cipher.ENCRYPT_MODE, secret);
      AlgorithmParameters params = cipher.getParameters();
      byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();

      /* Decrypt the message, given derived key and initialization vector. */
      cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
      new ByteArrayOutputStream baos;
      cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
      baos.write(cipher.update(ciphertext));
      baos.write(cipher.doFinal());
      return baos.toByteArray(); 
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
}

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Snippet ID:	#684
Snippet name:	Basic password-based encryption function (for StackOverflow)
Eternal ID of this version:	#684/1
Text MD5:	f37ef245c47591ba7d4897e0a4d22af6
Author:	stefan
Category:
Type:	JavaX source code
Public (visible to everyone):	Yes
Archived (hidden from active list):	No
Created/modified:	2015-07-26 19:50:16
Source code size:	3277 bytes / 98 lines
Pitched / IR pitched:	No / Yes
Views / Downloads:	850 / 783
Referenced in:	[show references]

< > BotCompany Repo | #684 // Basic password-based encryption function (for StackOverflow)

JavaX source code - run with: x30.jar

Author comment

1	!636
2	!quicknew
3
4	import java.security.*;
5	import java.security.spec.*;
6	import javax.crypto.*;
7	import javax.crypto.spec.*;
8
9	main {
10	psvm {
11	byte[] data = "hello".getBytes("UTF-8");
12	printHex(data);
13
14	Random ranGen = new SecureRandom();
15	byte[] salt = new byte[8]; // 8 grains of salt
16	ranGen.nextBytes(salt);
17
18	String pw = "pw";
19	byte[] enc = encrypt(data, pw.toCharArray(), salt);
20	printHex(enc);
21	System.out.println("enc length: " + enc.length);
22
23	byte[] dec = decrypt(enc, pw.toCharArray(), salt);
24	System.out.println("decrypted: " + new String(dec, "UTF-8"));
25	}
26
27	static void printHex(byte[] data) {
28	System.out.println(bytesToHex(data));
29	}
30
31	static String bytesToHex(byte[] bytes) {
32	return bytesToHex(bytes, 0, bytes.length);
33	}
34
35	static String bytesToHex(byte[] bytes, int ofs, int len) {
36	StringBuilder stringBuilder = new StringBuilder(len*2);
37	for (int i = 0; i < len; i++) {
38	String s = "0" + Integer.toHexString(bytes[ofs+i]);
39	stringBuilder.append(s.substring(s.length()-2, s.length()));
40	}
41	return stringBuilder.toString();
42	}
43
44	static SecretKey makeKey(char[] password, byte[] salt) tex {
45	/* Derive the key, given password and salt. */
46	SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
47
48	// only with unlimited strength:
49	//KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);
50
51	// Let's try this:
52	KeySpec spec = new PBEKeySpec(password, salt, 65536, 128);
53
54	SecretKey tmp = factory.generateSecret(spec);
55	SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
56	return secret;
57	}
58
59	public static byte[] encrypt(byte[] data, char[] password, byte[] salt) {
60	try {
61	SecretKey secret = makeKey(password, salt);
62
63	/* Encrypt the message. */
64	Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
65	cipher.init(Cipher.ENCRYPT_MODE, secret);
66	AlgorithmParameters params = cipher.getParameters();
67	byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
68	new ByteArrayOutputStream baos;
69	baos.write(cipher.update(data));
70	baos.write(cipher.doFinal());
71	byte[] ciphertext = baos.toByteArray();
72	return ciphertext;
73	} catch (Exception e) {
74	throw new RuntimeException(e);
75	}
76	}
77
78	static byte[] decrypt(byte[] ciphertext, char[] password, byte[] salt) {
79	try {
80	SecretKey secret = makeKey(password, salt);
81
82	Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
83	cipher.init(Cipher.ENCRYPT_MODE, secret);
84	AlgorithmParameters params = cipher.getParameters();
85	byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
86
87	/* Decrypt the message, given derived key and initialization vector. */
88	cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
89	new ByteArrayOutputStream baos;
90	cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
91	baos.write(cipher.update(ciphertext));
92	baos.write(cipher.doFinal());
93	return baos.toByteArray();
94	} catch (Exception e) {
95	throw new RuntimeException(e);
96	}
97	}
98	}