Android 加密解密

1. package EOE.android.demo;
   
2. 
   
3. import java.security.SecureRandom;
   
4. 
   
5. import javax.crypto.Cipher;
   
6. import javax.crypto.KeyGenerator;
   
7. import javax.crypto.SecretKey;
   
8. import javax.crypto.spec.SecretKeySpec;
   
9. 
   
10. /**
    
11. * Usage://用法
    
12. *

13. * String crypto = SimpleCrypto.encrypt(masterpassword, cleartext)//加密方法
    
14. * ...
    
15. * String cleartext = SimpleCrypto.decrypt(masterpassword, crypto)//解密方法
    
16. *
    
17. * @author ferenc.hechler
    
18. */
    
19. public class SimpleCrypto {
    
20. 
    
21. public static String encrypt(String seed, String cleartext) throws Exception {
    
22. byte[] rawKey = getRawKey(seed.getBytes());
    
23. byte[] result = encrypt(rawKey, cleartext.getBytes());
    
24. return toHex(result);
    
25. }
    
26. 
    
27. public static String decrypt(String seed, String encrypted) throws Exception {
    
28. byte[] rawKey = getRawKey(seed.getBytes());
    
29. byte[] enc = toByte(encrypted);
    
30. byte[] result = decrypt(rawKey, enc);
    
31. return new String(result);
    
32. }
    
33. 
    
34. private static byte[] getRawKey(byte[] seed) throws Exception {
    
35. KeyGenerator kgen = KeyGenerator.getInstance("AES");
    
36. SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
    
37. sr.setSeed(seed);
    
38. kgen.init(128, sr); // 192 and 256 bits may not be available
    
39. SecretKey skey = kgen.generateKey();
    
40. byte[] raw = skey.getEncoded();
    
41. return raw;
    
42. }
    
43. 
    
44. 
    
45. private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
    
46. SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    
47. Cipher cipher = Cipher.getInstance("AES");
    
48. cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
    
49. byte[] encrypted = cipher.doFinal(clear);
    
50. return encrypted;
    
51. }
    
52. 
    
53. private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
    
54. SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    
55. Cipher cipher = Cipher.getInstance("AES");
    
56. cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    
57. byte[] decrypted = cipher.doFinal(encrypted);
    
58. return decrypted;
    
59. }
    
60. 
    
61. public static String toHex(String txt) {
    
62. return toHex(txt.getBytes());
    
63. }
    
64. public static String fromHex(String hex) {
    
65. return new String(toByte(hex));
    
66. }
    
67. 
    
68. public static byte[] toByte(String hexString) {
    
69. int len = hexString.length()/2;
    
70. byte[] result = new byte[len];
    
71. for (int i = 0; i < len; i++)
    
72. result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
    
73. return result;
    
74. }
    
75. 
    
76. public static String toHex(byte[] buf) {
    
77. if (buf == null)
    
78. return "";
    
79. StringBuffer result = new StringBuffer(2*buf.length);
    
80. for (int i = 0; i < buf.length; i++) {
    
81. appendHex(result, buf[i]);
    
82. }
    
83. return result.toString();
    
84. }
    
85. private final static String HEX = "0123456789ABCDEF";
    
86. private static void appendHex(StringBuffer sb, byte b) {
    
87. sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
    
88. }
    
89. 
    
90. }