Java加密技术（一）

加密解密，曾经是我一个毕业设计的重要组件。在工作了多年以后回想当时那个加密、解密算法，实在是太单纯了。Java代码

1. /**?
2. ?*?BASE64解密?
3. ?*??
4. ?*?@param?key?
5. ?*?@return?
6. ?*?@throws?Exception?
7. ?*/??
8. public?static?byte[]?decryptBASE64(String?key)?throws?Exception?{??
9. ????return?(new?BASE64Decoder()).decodeBuffer(key);??
10. }??
11. ??
12. /**?
13. ?*?BASE64加密?
14. ?*??
15. ?*?@param?key?
16. ?*?@return?
17. ?*?@throws?Exception?
18. ?*/??
19. public?static?String?encryptBASE64(byte[]?key)?throws?Exception?{??
20. ????return?(new?BASE64Encoder()).encodeBuffer(key);??
21. }??

主要就是BASE64Encoder、BASE64Decoder两个类，我们只需要知道使用对应的方法即可。另，BASE加密后产生的字节位数是8的倍数，如果不够位数以=符号填充。Java代码

1. /**?
2. ?*?MD5加密?
3. ?*??
4. ?*?@param?data?
5. ?*?@return?
6. ?*?@throws?Exception?
7. ?*/??
8. public?static?byte[]?encryptMD5(byte[]?data)?throws?Exception?{??
9. ??
10. ????MessageDigest?md5?=?MessageDigest.getInstance(KEY_MD5);??
11. ????md5.update(data);??
12. ??
13. ????return?md5.digest();??
14. ??
15. }??

通常我们不直接使用上述MD5加密。通常将MD5产生的字节数组交给BASE64再加密一把，得到相应的字符串。Java代码

1. ????/**?
2. ?????*?SHA加密?
3. ?????*??
4. ?????*?@param?data?
5. ?????*?@return?
6. ?????*?@throws?Exception?
7. ?????*/??
8. ????public?static?byte[]?encryptSHA(byte[]?data)?throws?Exception?{??
9. ??
10. ????????MessageDigest?sha?=?MessageDigest.getInstance(KEY_SHA);??
11. ????????sha.update(data);??
12. ??
13. ????????return?sha.digest();??
14. ??
15. ????}??
16. }??

HMACJava代码

1. /**?
2. ?*?初始化HMAC密钥?
3. ?*??
4. ?*?@return?
5. ?*?@throws?Exception?
6. ?*/??
7. public?static?String?initMacKey()?throws?Exception?{??
8. ????KeyGenerator?keyGenerator?=?KeyGenerator.getInstance(KEY_MAC);??
9. ??
10. ????SecretKey?secretKey?=?keyGenerator.generateKey();??
11. ????return?encryptBASE64(secretKey.getEncoded());??
12. }??
13. ??
14. /**?
15. ?*?HMAC加密?
16. ?*??
17. ?*?@param?data?
18. ?*?@param?key?
19. ?*?@return?
20. ?*?@throws?Exception?
21. ?*/??
22. public?static?byte[]?encryptHMAC(byte[]?data,?String?key)?throws?Exception?{??
23. ??
24. ????SecretKey?secretKey?=?new?SecretKeySpec(decryptBASE64(key),?KEY_MAC);??
25. ????Mac?mac?=?Mac.getInstance(secretKey.getAlgorithm());??
26. ????mac.init(secretKey);??
27. ??
28. ????return?mac.doFinal(data);??
29. ??
30. }??

给出一个完整类，如下：Java代码

1. import?java.security.MessageDigest;??
2. ??
3. import?javax.crypto.KeyGenerator;??
4. import?javax.crypto.Mac;??
5. import?javax.crypto.SecretKey;??
6. ??
7. import?sun.misc.BASE64Decoder;??
8. import?sun.misc.BASE64Encoder;??
9. ??
10. /**?
11. ?*?基础加密组件?
12. ?*??
13. ?*?@author?梁栋?
14. ?*?@version?1.0?
15. ?*?@since?1.0?
16. ?*/??
17. public?abstract?class?Coder?{??
18. ????public?static?final?String?KEY_SHA?=?"SHA";??
19. ????public?static?final?String?KEY_MD5?=?"MD5";??
20. ??
21. ????/**?
22. ?????*?MAC算法可选以下多种算法?
23. ?????*??
24. ?????*?<pre>?
25. ?????*?HmacMD5??
26. ?????*?HmacSHA1??
27. ?????*?HmacSHA256??
28. ?????*?HmacSHA384??
29. ?????*?HmacSHA512?
30. ?????*?</pre>?
31. ?????*/??
32. ????public?static?final?String?KEY_MAC?=?"HmacMD5";??
33. ??
34. ????/**?
35. ?????*?BASE64解密?
36. ?????*??
37. ?????*?@param?key?
38. ?????*?@return?
39. ?????*?@throws?Exception?
40. ?????*/??
41. ????public?static?byte[]?decryptBASE64(String?key)?throws?Exception?{??
42. ????????return?(new?BASE64Decoder()).decodeBuffer(key);??
43. ????}??
44. ??
45. ????/**?
46. ?????*?BASE64加密?
47. ?????*??
48. ?????*?@param?key?
49. ?????*?@return?
50. ?????*?@throws?Exception?
51. ?????*/??
52. ????public?static?String?encryptBASE64(byte[]?key)?throws?Exception?{??
53. ????????return?(new?BASE64Encoder()).encodeBuffer(key);??
54. ????}??
55. ??
56. ????/**?
57. ?????*?MD5加密?
58. ?????*??
59. ?????*?@param?data?
60. ?????*?@return?
61. ?????*?@throws?Exception?
62. ?????*/??
63. ????public?static?byte[]?encryptMD5(byte[]?data)?throws?Exception?{??
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