关于使用JS前台加密、JAVA后台解密的RSA实现，RSA加密和签名

用RSA非对称加密方式实现。后台生成rsa密钥对，然后在登陆页面设置rsa公钥，提交时用公钥加密密码，生成的密文传到后台，用私钥解密，获取密码明文。

这样客户端只需要知道rsa加密方式和公钥，前台不知道私钥是无法解密的，此解决方案还是相对比较安全的。

附件是参照网友资料的java+JS的实现，放在这里供大家下载。访问方式/RSA/login.jsp。

需要到http://www.bouncycastle.org下载bcprov-jdk14-123.jar文件。

因为后台要转换成bigint，所以对明文长度有些限制：

总长度不超过126（1汉字长度为9），如下两个字符串：

阿送大法散得阿送大法散得阿送
1232132131231231232131232K1232132131231231232131232K1232132131231231232131232K1232132131231231232131232K1234567890123456789012

RSA速度 
 * 由于进行的都是大数计算，使得RSA最快的情况也比DES慢上100倍，无论 是软件还是硬件实现。 
 * 速度一直是RSA的缺陷。一般来说只用于少量数据 加密。

Util.java

1. package RSA;
3. /**
4. *
5. */
7. import java.io.ByteArrayOutputStream;
8. import java.io.FileInputStream;
9. import java.io.FileOutputStream;
10. import java.io.ObjectInputStream;
11. import java.io.ObjectOutputStream;
12. import java.math.BigInteger;
13. import java.security.KeyFactory;
14. import java.security.KeyPair;
15. import java.security.KeyPairGenerator;
16. import java.security.NoSuchAlgorithmException;
17. import java.security.PrivateKey;
18. import java.security.PublicKey;
19. import java.security.SecureRandom;
20. import java.security.interfaces.RSAPrivateKey;
21. import java.security.interfaces.RSAPublicKey;
22. import java.security.spec.InvalidKeySpecException;
23. import java.security.spec.RSAPrivateKeySpec;
24. import java.security.spec.RSAPublicKeySpec;
26. import javax.crypto.Cipher;
28. /**
29. * RSA 工具类。提供加密，解密，生成密钥对等方法。
30. * 需要到http://www.bouncycastle.org下载bcprov-jdk14-123.jar。
31. *
32. */
33. public class RSAUtil {
35. private static String RSAKeyStore = "C:/RSAKey.txt";
36. /**
37. * * 生成密钥对 *
38. *
39. * @return KeyPair *
40. * @throws EncryptException
41. */
42. public static KeyPair generateKeyPair() throws Exception {
43. try {
44. KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA",
45. new org.bouncycastle.jce.provider.BouncyCastleProvider());
46. final int KEY_SIZE = 1024;// 没什么好说的了，这个值关系到块加密的大小，可以更改，但是不要太大，否则效率会低
47. keyPairGen.initialize(KEY_SIZE, new SecureRandom());
48. KeyPair keyPair = keyPairGen.generateKeyPair();
50. System.out.println(keyPair.getPrivate());
51. System.out.println(keyPair.getPublic());
53. saveKeyPair(keyPair);
54. return keyPair;
55. } catch (Exception e) {
56. throw new Exception(e.getMessage());
57. }
58. }
60. public static KeyPair getKeyPair() throws Exception {
61. FileInputStream fis = new FileInputStream(RSAKeyStore);
62. ObjectInputStream oos = new ObjectInputStream(fis);
63. KeyPair kp = (KeyPair) oos.readObject();
64. oos.close();
65. fis.close();
66. return kp;
67. }
69. public static void saveKeyPair(KeyPair kp) throws Exception {
71. FileOutputStream fos = new FileOutputStream(RSAKeyStore);
72. ObjectOutputStream oos = new ObjectOutputStream(fos);
73. // 生成密钥
74. oos.writeObject(kp);
75. oos.close();
76. fos.close();
77. }
79. /**
80. * * 生成公钥 *
81. *
82. * @param modulus *
83. * @param publicExponent *
84. * @return RSAPublicKey *
85. * @throws Exception
86. */
87. public static RSAPublicKey generateRSAPublicKey(byte[] modulus,
88. byte[] publicExponent) throws Exception {
89. KeyFactory keyFac = null;
90. try {
91. keyFac = KeyFactory.getInstance("RSA",
92. new org.bouncycastle.jce.provider.BouncyCastleProvider());
93. } catch (NoSuchAlgorithmException ex) {
94. throw new Exception(ex.getMessage());
95. }
97. RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(
98. modulus), new BigInteger(publicExponent));
99. try {
100. return (RSAPublicKey) keyFac.generatePublic(pubKeySpec);
101. } catch (InvalidKeySpecException ex) {
102. throw new Exception(ex.getMessage());
103. }
104. }
106. /**
107. * * 生成私钥 *
108. *
109. * @param modulus *
110. * @param privateExponent *
111. * @return RSAPrivateKey *
112. * @throws Exception
113. */
114. public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus,
115. byte[] privateExponent) throws Exception {
116. KeyFactory keyFac = null;
117. try {
118. keyFac = KeyFactory.getInstance("RSA",
119. new org.bouncycastle.jce.provider.BouncyCastleProvider());
120. } catch (NoSuchAlgorithmException ex) {
121. throw new Exception(ex.getMessage());
122. }
124. RSAPrivateKeySpec priKeySpec = new RSAPrivateKeySpec(new BigInteger(
125. modulus), new BigInteger(privateExponent));
126. try {
127. return (RSAPrivateKey) keyFac.generatePrivate(priKeySpec);
128. } catch (InvalidKeySpecException ex) {
129. throw new Exception(ex.getMessage());
130. }
131. }
133. /**
134. * * 加密 *
135. *
136. * @param key
137. * 加密的密钥 *
138. * @param data
139. * 待加密的明文数据 *
140. * @return 加密后的数据 *
141. * @throws Exception
142. */
143. public static byte[] encrypt(PublicKey pk, byte[] data) throws Exception {
144. try {
145. Cipher cipher = Cipher.getInstance("RSA",
146. new org.bouncycastle.jce.provider.BouncyCastleProvider());
147. cipher.init(Cipher.ENCRYPT_MODE, pk);
148. int blockSize = cipher.getBlockSize();// 获得加密块大小，如：加密前数据为128个byte，而key_size=1024
149. // 加密块大小为127
150. // byte,加密后为128个byte;因此共有2个加密块，第一个127
151. // byte第二个为1个byte
152. int outputSize = cipher.getOutputSize(data.length);// 获得加密块加密后块大小
153. int leavedSize = data.length % blockSize;
154. int blocksSize = leavedSize != 0 ? data.length / blockSize + 1
155. : data.length / blockSize;
156. byte[] raw = new byte[outputSize * blocksSize];
157. int i = 0;
158. while (data.length - i * blockSize > 0) {
159. if (data.length - i * blockSize > blockSize)
160. cipher.doFinal(data, i * blockSize, blockSize, raw, i
161. * outputSize);
162. else
163. cipher.doFinal(data, i * blockSize, data.length - i
164. * blockSize, raw, i * outputSize);
165. // 这里面doUpdate方法不可用，查看源代码后发现每次doUpdate后并没有什么实际动作除了把byte[]放到
166. // ByteArrayOutputStream中，而最后doFinal的时候才将所有的byte[]进行加密，可是到了此时加密块大小很可能已经超出了
167. // OutputSize所以只好用dofinal方法。
169. i++;
170. }
171. return raw;
172. } catch (Exception e) {
173. throw new Exception(e.getMessage());
174. }
175. }
177. /**
178. * * 解密 *
179. *
180. * @param key
181. * 解密的密钥 *
182. * @param raw
183. * 已经加密的数据 *
184. * @return 解密后的明文 *
185. * @throws Exception
186. */
187. public static byte[] decrypt(PrivateKey pk, byte[] raw) throws Exception {
188. try {
189. Cipher cipher = Cipher.getInstance("RSA",
190. new org.bouncycastle.jce.provider.BouncyCastleProvider());
191. cipher.init(cipher.DECRYPT_MODE, pk);
192. int blockSize = cipher.getBlockSize();
193. ByteArrayOutputStream bout = new ByteArrayOutputStream(64);
194. int j = 0;
196. while (raw.length - j * blockSize > 0) {
197. bout.write(cipher.doFinal(raw, j * blockSize, blockSize));
198. j++;
199. }
200. return bout.toByteArray();
201. } catch (Exception e) {
202. throw new Exception(e.getMessage());
203. }
204. }
206. /**
207. * * *
208. *
209. * @param args *
210. * @throws Exception
211. */
212. public static void main(String[] args) throws Exception {
213. RSAPublicKey rsap = (RSAPublicKey) RSAUtil.generateKeyPair().getPublic();
214. String test = "hello world";
215. byte[] en_test = encrypt(getKeyPair().getPublic(), test.getBytes());
216. byte[] de_test = decrypt(getKeyPair().getPrivate(), en_test);
217. System.out.println(new String(de_test));
218. }
219. }

1. package RSA;
3. //login
4. /*
5. * Generated by MyEclipse Struts
6. * Template path: templates/java/JavaClass.vtl
7. */
8. import java.math.BigInteger;
9. import java.net.URLDecoder;
10. import java.net.URLEncoder;
12. import javax.servlet.http.HttpServletRequest;
13. import javax.servlet.http.HttpServletResponse;
15. import RSA.RSAUtil;
17. /**
18. * MyEclipse Struts Creation date: 06-28-2008
19. *
20. * XDoclet definition:
21. *
22. * @struts.action path="/login" name="loginForm" input="/login.jsp"
23. * scope="request" validate="true"
24. * @struts.action-forward name="error" path="/error.jsp"
25. * @struts.action-forward name="success" path="/success.jsp"
26. */
27. public class LoginAction {
28. /*
29. * Generated Methods
30. */
32. /**
33. * Method execute
34. *
35. * @param mapping
36. * @param form
37. * @param request
38. * @param response
39. * @return ActionForward
40. */
41. public boolean execute(HttpServletRequest request,
42. HttpServletResponse response) throws Exception {
43. String pwd ;
44. String result = request.getParameter("result");
45. System.out.println("原文加密后为：");
46. System.out.println(result);
47. byte[] en_result = new BigInteger(result, 16).toByteArray();
48. //System.out.println("转成byte[]" + new String(en_result));
49. byte[] de_result = RSAUtil.decrypt(RSAUtil.getKeyPair().getPrivate(),
50. en_result);
51. System.out.println("还原密文：");
52. System.out.println(new String(de_result));
53. StringBuffer sb = new StringBuffer();
54. sb.append(new String(de_result));
55. pwd = sb.reverse().toString();
56. System.out.println(sb);
57. System.out.println("=================================");
58. pwd = URLDecoder.decode(pwd,"UTF-8");//
59. System.out.println(pwd);
60. request.setAttribute("pwd", pwd);
61. return true;
62. }
63. }

1. <%@ page language="java" pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>
3. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
4. <html:html lang="true">
5. <head>
6. <title>login</title>
8. <script type="text/javascript" src="js/RSA.js"></script>
9. <script type="text/javascript" src="js/BigInt.js"></script>
10. <script type="text/javascript" src="js/Barrett.js"></script>
12. <script type="text/javascript">
13. function rsalogin(){
14. var thisPwd = document.getElementById("password").value;
15. bodyRSA();
16. var result = encryptedString(key, encodeURIComponent(thisPwd));
17. //alert(encodeURIComponent(thisPwd)+"\r\n"+result);
18. loginForm.action="loginCHK.jsp?result="+result;
19. loginForm.submit();
20. }
21. var key ;
22. function bodyRSA(){
23. setMaxDigits(130);
24. key = new RSAKeyPair("10001","","8246a46f44fc4d961e139fd70f4787d272d374532f4d2d9b7cbaad6a15a8c1301319aa6b3f30413b859351c71938aec516fa7147b69168b195e81df46b6bed7950cf3a1c719d42175f73d7c97a85d7d20a9e83688b92f05b3059bb2ff75cd7190a042cd2db97ebc2ab4da366f2a7085556ed613b5a39c9fdd2bb2595d1dc23b5");
25. }
26. </script>
27. </head>
29. <body>
30. <form method="post" name="loginForm" target=_blank>
31. <table border="0">
32. <tr>
33. <td>
34. Password:
35. </td>
36. <td>
37. <input type='text' name="password" id=password style='width:400px' value="my passwd"/>
38. </td>
39. </tr>
40. <tr>
41. <td colspan="2" align="center">
42. <input type="button" value="SUBMIT" οnclick="rsalogin();" />
43. </td>
44. </tr>
45. </table>
46. </form>
47. </body>
48. </html:html>

1. <%@ page language="java" pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>
3. <jsp:directive.page import="RSA.LoginAction"/>
5. <%
6. LoginAction la = new LoginAction();
7. la.execute(request ,response);
8. %>
9. pwd is [<%=request.getAttribute("pwd")%>]