Java加密技术（六）——数字签名算法DSA

接下来我们介绍DSA数字签名，非对称加密的另一种实现。
DSA
DSA-Digital Signature Algorithm 是Schnorr和ElGamal签名算法的变种，被美国NIST作为DSS(DigitalSignature Standard)。简单的说，这是一种更高级的验证方式，用作数字签名。不单单只有公钥、私钥，还有数字签名。私钥加密生成数字签名，公钥验证数据及签名。如果数据和签名不匹配则认为验证失败！数字签名的作用就是校验数据在传输过程中不被修改。数字签名，是单向加密的升级！

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通过java代码实现如下： Coder类见Java加密技术（一）

Java代码

1. importjava.security.Key;
2. importjava.security.KeyFactory;
3. importjava.security.KeyPair;
4. importjava.security.KeyPairGenerator;
5. importjava.security.PrivateKey;
6. importjava.security.PublicKey;
7. importjava.security.SecureRandom;
8. importjava.security.Signature;
9. importjava.security.interfaces.DSAPrivateKey;
10. importjava.security.interfaces.DSAPublicKey;
11. importjava.security.spec.PKCS8EncodedKeySpec;
12. importjava.security.spec.X509EncodedKeySpec;
13. importjava.util.HashMap;
14. importjava.util.Map;
16. /**
17. *DSA安全编码组件
18. *
19. *@author梁栋
20. *@version1.0
21. *@since1.0
22. */
23. publicabstractclassDSACoderextendsCoder{
25. publicstaticfinalStringALGORITHM="DSA";
27. /**
28. *默认密钥字节数
29. *
30. *<pre>
31. *DSA
32. *DefaultKeysize1024
33. *Keysizemustbeamultipleof64,rangingfrom512to1024(inclusive).
34. *</pre>
35. */
36. privatestaticfinalintKEY_SIZE=1024;
38. /**
39. *默认种子
40. */
41. privatestaticfinalStringDEFAULT_SEED="0f22507a10bbddd07d8a3082122966e3";
43. privatestaticfinalStringPUBLIC_KEY="DSAPublicKey";
44. privatestaticfinalStringPRIVATE_KEY="DSAPrivateKey";
46. /**
47. *用私钥对信息生成数字签名
48. *
49. *@paramdata
50. *加密数据
51. *@paramprivateKey
52. *私钥
53. *
54. *@return
55. *@throwsException
56. */
57. publicstaticStringsign(byte[]data,StringprivateKey)throwsException{
58. //解密由base64编码的私钥
59. byte[]keyBytes=decryptBASE64(privateKey);
61. //构造PKCS8EncodedKeySpec对象
62. PKCS8EncodedKeySpecpkcs8KeySpec=newPKCS8EncodedKeySpec(keyBytes);
64. //KEY_ALGORITHM指定的加密算法
65. KeyFactorykeyFactory=KeyFactory.getInstance(ALGORITHM);
67. //取私钥匙对象
68. PrivateKeypriKey=keyFactory.generatePrivate(pkcs8KeySpec);
70. //用私钥对信息生成数字签名
71. Signaturesignature=Signature.getInstance(keyFactory.getAlgorithm());
72. signature.initSign(priKey);
73. signature.update(data);
75. returnencryptBASE64(signature.sign());
76. }
78. /**
79. *校验数字签名
80. *
81. *@paramdata
82. *加密数据
83. *@parampublicKey
84. *公钥
85. *@paramsign
86. *数字签名
87. *
88. *@return校验成功返回true失败返回false
89. *@throwsException
90. *
91. */
92. publicstaticbooleanverify(byte[]data,StringpublicKey,Stringsign)
93. throwsException{
95. //解密由base64编码的公钥
96. byte[]keyBytes=decryptBASE64(publicKey);
98. //构造X509EncodedKeySpec对象
99. X509EncodedKeySpeckeySpec=newX509EncodedKeySpec(keyBytes);
101. //ALGORITHM指定的加密算法
102. KeyFactorykeyFactory=KeyFactory.getInstance(ALGORITHM);
104. //取公钥匙对象
105. PublicKeypubKey=keyFactory.generatePublic(keySpec);
107. Signaturesignature=Signature.getInstance(keyFactory.getAlgorithm());
108. signature.initVerify(pubKey);
109. signature.update(data);
111. //验证签名是否正常
112. returnsignature.verify(decryptBASE64(sign));
113. }
115. /**
116. *生成密钥
117. *
118. *@paramseed
119. *种子
120. *@return密钥对象
121. *@throwsException
122. */
123. publicstaticMap<String,Object>initKey(Stringseed)throwsException{
124. KeyPairGeneratorkeygen=KeyPairGenerator.getInstance(ALGORITHM);
125. //初始化随机产生器
126. SecureRandomsecureRandom=newSecureRandom();
127. secureRandom.setSeed(seed.getBytes());
128. keygen.initialize(KEY_SIZE,secureRandom);
130. KeyPairkeys=keygen.genKeyPair();
132. DSAPublicKeypublicKey=(DSAPublicKey)keys.getPublic();
133. DSAPrivateKeyprivateKey=(DSAPrivateKey)keys.getPrivate();
135. Map<String,Object>map=newHashMap<String,Object>(2);
136. map.put(PUBLIC_KEY,publicKey);
137. map.put(PRIVATE_KEY,privateKey);
139. returnmap;
140. }
142. /**
143. *默认生成密钥
144. *
145. *@return密钥对象
146. *@throwsException
147. */
148. publicstaticMap<String,Object>initKey()throwsException{
149. returninitKey(DEFAULT_SEED);
150. }
152. /**
153. *取得私钥
154. *
155. *@paramkeyMap
156. *@return
157. *@throwsException
158. */
159. publicstaticStringgetPrivateKey(Map<String,Object>keyMap)
160. throwsException{
161. Keykey=(Key)keyMap.get(PRIVATE_KEY);
163. returnencryptBASE64(key.getEncoded());
164. }
166. /**
167. *取得公钥
168. *
169. *@paramkeyMap
170. *@return
171. *@throwsException
172. */
173. publicstaticStringgetPublicKey(Map<String,Object>keyMap)
174. throwsException{
175. Keykey=(Key)keyMap.get(PUBLIC_KEY);
177. returnencryptBASE64(key.getEncoded());
178. }
179. }

再给出一个测试类：

Java代码

1. importstaticorg.junit.Assert.*;
3. importjava.util.Map;
5. importorg.junit.Test;
7. /**
8. *
9. *@author梁栋
10. *@version1.0
11. *@since1.0
12. */
13. publicclassDSACoderTest{
15. @Test
16. publicvoidtest()throwsException{
17. StringinputStr="abc";
18. byte[]data=inputStr.getBytes();
20. //构建密钥
21. Map<String,Object>keyMap=DSACoder.initKey();
23. //获得密钥
24. StringpublicKey=DSACoder.getPublicKey(keyMap);
25. StringprivateKey=DSACoder.getPrivateKey(keyMap);
27. System.err.println("公钥:\r"+publicKey);
28. System.err.println("私钥:\r"+privateKey);
30. //产生签名
31. Stringsign=DSACoder.sign(data,privateKey);
32. System.err.println("签名:\r"+sign);
34. //验证签名
35. booleanstatus=DSACoder.verify(data,publicKey,sign);
36. System.err.println("状态:\r"+status);
37. assertTrue(status);
39. }
41. }

控制台输出：

Console代码

1. 公钥:
2. MIIBtzCCASwGByqGSM44BAEwggEfAoGBAP1/U4EddRIpUt9KnC7s5Of2EbdSPO9EAMMeP4C2USZp
3. RV1AIlH7WT2NWPq/xfW6MPbLm1Vs14E7gB00b/JmYLdrmVClpJ+f6AR7ECLCT7up1/63xhv4O1fn
4. xqimFQ8E+4P208UewwI1VBNaFpEy9nXzrith1yrv8iIDGZ3RSAHHAhUAl2BQjxUjC8yykrmCouuE
5. C/BYHPUCgYEA9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCBgLRJ
6. FnEj6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTxvqhRkImo
7. g9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSoDgYQAAoGAIu4RUlcQLp49PI0MrbssOY+3uySVnp0TULSv
8. 5T4VaHoKzsLHgGTrwOvsGA+V3yCNl2WDu3D84bSLF7liTWgOj+SMOEaPk4VyRTlLXZWGPsf1Mfd9
9. 21XAbMeVyKDSHHVGbMjBScajf3bXooYQMlyoHiOt/WrCo+mv7efstMM0PGo=
11. 私钥:
12. MIIBTAIBADCCASwGByqGSM44BAEwggEfAoGBAP1/U4EddRIpUt9KnC7s5Of2EbdSPO9EAMMeP4C2
13. USZpRV1AIlH7WT2NWPq/xfW6MPbLm1Vs14E7gB00b/JmYLdrmVClpJ+f6AR7ECLCT7up1/63xhv4
14. O1fnxqimFQ8E+4P208UewwI1VBNaFpEy9nXzrith1yrv8iIDGZ3RSAHHAhUAl2BQjxUjC8yykrmC
15. ouuEC/BYHPUCgYEA9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCB
16. gLRJFnEj6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTxvqhR
17. kImog9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSoEFwIVAIegLUtmm2oQKQJTOiLugHTSjl/q
19. 签名:
20. MC0CFQCMg0J/uZmF8GuRpr3TNq48w60nDwIUJCyYNah+HtbU6NcQfy8Ac6LeLQs=
22. 状态:
23. true

注意状态为true，就验证成功！