Java加密技术（五）

?? 接下来我们分析DH加密算法，一种适基于密钥一致协议的加密算法。?

通过java代码实现如下：Coder类见Java代码

1. import?java.security.Key;??
2. import?java.security.KeyFactory;??
3. import?java.security.KeyPair;??
4. import?java.security.KeyPairGenerator;??
5. import?java.security.PublicKey;??
6. import?java.security.spec.PKCS8EncodedKeySpec;??
7. import?java.security.spec.X509EncodedKeySpec;??
8. import?java.util.HashMap;??
9. import?java.util.Map;??
10. ??
11. import?javax.crypto.Cipher;??
12. import?javax.crypto.KeyAgreement;??
13. import?javax.crypto.SecretKey;??
14. import?javax.crypto.interfaces.DHPrivateKey;??
15. import?javax.crypto.interfaces.DHPublicKey;??
16. import?javax.crypto.spec.DHParameterSpec;??
17. ??
18. /**?
19. ?*?DH安全编码组件?
20. ?*??
21. ?*?@author?梁栋?
22. ?*?@version?1.0?
23. ?*?@since?1.0?
24. ?*/??
25. public?abstract?class?DHCoder?extends?Coder?{??
26. ????public?static?final?String?ALGORITHM?=?"DH";??
27. ??
28. ????/**?
29. ?????*?默认密钥字节数?
30. ?????*??
31. ?????*?<pre>?
32. ?????*?DH?
33. ?????*?Default?Keysize?1024???
34. ?????*?Keysize?must?be?a?multiple?of?64,?ranging?from?512?to?1024?(inclusive).?
35. ?????*?</pre>?
36. ?????*/??
37. ????private?static?final?int?KEY_SIZE?=?1024;??
38. ??
39. ????/**?
40. ?????*?DH加密下需要一种对称加密算法对数据加密，这里我们使用DES，也可以使用其他对称加密算法。?
41. ?????*/??
42. ????public?static?final?String?SECRET_ALGORITHM?=?"DES";??
43. ????private?static?final?String?PUBLIC_KEY?=?"DHPublicKey";??
44. ????private?static?final?String?PRIVATE_KEY?=?"DHPrivateKey";??
45. ??
46. ????/**?
47. ?????*?初始化甲方密钥?
48. ?????*??
49. ?????*?@return?
50. ?????*?@throws?Exception?
51. ?????*/??
52. ????public?static?Map<String,?Object>?initKey()?throws?Exception?{??
53. ????????KeyPairGenerator?keyPairGenerator?=?KeyPairGenerator??
54. ????????????????.getInstance(ALGORITHM);??
55. ????????keyPairGenerator.initialize(KEY_SIZE);??
56. ??
57. ????????KeyPair?keyPair?=?keyPairGenerator.generateKeyPair();??
58. ??
59. ????????//?甲方公钥??
60. ????????DHPublicKey?publicKey?=?(DHPublicKey)?keyPair.getPublic();??
61. ??
62. ????????//?甲方私钥??
63. ????????DHPrivateKey?privateKey?=?(DHPrivateKey)?keyPair.getPrivate();??
64. ??
65. ????????Map<String,?Object>?keyMap?=?new?HashMap<String,?Object>(2);??
66. ??
67. ????????keyMap.put(PUBLIC_KEY,?publicKey);??
68. ????????keyMap.put(PRIVATE_KEY,?privateKey);??
69. ????????return?keyMap;??
70. ????}??
71. ??
72. ????/**?
73. ?????*?初始化乙方密钥?
74. ?????*??
75. ?????*?@param?key?
76. ?????*????????????甲方公钥?
77. ?????*?@return?
78. ?????*?@throws?Exception?
79. ?????*/??
80. ????public?static?Map<String,?Object>?initKey(String?key)?throws?Exception?{??
81. ????????//?解析甲方公钥??
82. ????????byte[]?keyBytes?=?decryptBASE64(key);??
83. ????????X509EncodedKeySpec?x509KeySpec?=?new?X509EncodedKeySpec(keyBytes);??
84. ????????KeyFactory?keyFactory?=?KeyFactory.getInstance(ALGORITHM);??
85. ????????PublicKey?pubKey?=?keyFactory.generatePublic(x509KeySpec);??
86. ??
87. ????????//?由甲方公钥构建乙方密钥??
88. ????????DHParameterSpec?dhParamSpec?=?((DHPublicKey)?pubKey).getParams();??
89. ??
90. ????????KeyPairGenerator?keyPairGenerator?=?KeyPairGenerator??
91. ????????????????.getInstance(keyFactory.getAlgorithm());??
92. ????????keyPairGenerator.initialize(dhParamSpec);??
93. ??
94. ????????KeyPair?keyPair?=?keyPairGenerator.generateKeyPair();??
95. ??
96. ????????//?乙方公钥??
97. ????????DHPublicKey?publicKey?=?(DHPublicKey)?keyPair.getPublic();??
98. ??
99. ????????//?乙方私钥??
100. ????????DHPrivateKey?privateKey?=?(DHPrivateKey)?keyPair.getPrivate();??
101. ??
102. ????????Map<String,?Object>?keyMap?=?new?HashMap<String,?Object>(2);??
103. ??
104. ????????keyMap.put(PUBLIC_KEY,?publicKey);??
105. ????????keyMap.put(PRIVATE_KEY,?privateKey);??
106. ??
107. ????????return?keyMap;??
108. ????}??
109. ??
110. ????/**?
111. ?????*?加密<br>?
112. ?????*??
113. ?????*?@param?data?
114. ?????*????????????待加密数据?
115. ?????*?@param?publicKey?
116. ?????*????????????甲方公钥?
117. ?????*?@param?privateKey?
118. ?????*????????????乙方私钥?
119. ?????*?@return?
120. ?????*?@throws?Exception?
121. ?????*/??
122. ????public?static?byte[]?encrypt(byte[]?data,?String?publicKey,??
123. ????????????String?privateKey)?throws?Exception?{??
124. ??
125. ????????//?生成本地密钥??
126. ????????SecretKey?secretKey?=?getSecretKey(publicKey,?privateKey);??
127. ??
128. ????????//?数据加密??
129. ????????Cipher?cipher?=?Cipher.getInstance(secretKey.getAlgorithm());??
130. ????????cipher.init(Cipher.ENCRYPT_MODE,?secretKey);??
131. ??
132. ????????return?cipher.doFinal(data);??
133. ????}??
134. ??
135. ????/**?
136. ?????*?解密<br>?
137. ?????*??
138. ?????*?@param?data?
139. ?????*????????????待解密数据?
140. ?????*?@param?publicKey?
141. ?????*????????????乙方公钥?
142. ?????*?@param?privateKey?
143. ?????*????????????乙方私钥?
144. ?????*?@return?
145. ?????*?@throws?Exception?
146. ?????*/??
147. ????public?static?byte[]?decrypt(byte[]?data,?String?publicKey,??
148. ????????????String?privateKey)?throws?Exception?{??
149. ??
150. ????????//?生成本地密钥??
151. ????????SecretKey?secretKey?=?getSecretKey(publicKey,?privateKey);??
152. ????????//?数据解密??
153. ????????Cipher?cipher?=?Cipher.getInstance(secretKey.getAlgorithm());??
154. ????????cipher.init(Cipher.DECRYPT_MODE,?secretKey);??
155. ??
156. ????????return?cipher.doFinal(data);??
157. ????}??
158. ??
159. ????/**?
160. ?????*?构建密钥?
161. ?????*??
162. ?????*?@param?publicKey?
163. ?????*????????????公钥?
164. ?????*?@param?privateKey?
165. ?????*????????????私钥?
166. ?????*?@return?
167. ?????*?@throws?Exception?
168. ?????*/??
169. ????private