Java中使用OpenSSL生成的RSA公私钥

Posted 2020-09-19

RSA是什么：RSA公钥加密算法是1977年由Ron Rivest、Adi Shamirh和LenAdleman在（美国麻省理工学院）开发的。RSA取名来自开发他们三者的名字。RSA是目前最有影响力的公钥加密算法，它能够抵抗到目前为止已知的所有密码攻击，已被ISO推荐为公钥数据加密标准。目前该加密方式广泛用于网上银行、数字签名等场合。RSA算法基于一个十分简单的数论事实：将两个大素数相乘十分容易，但那时想要对其乘积进行因式分解却极其困难，因此可以将乘积公开作为加密密钥。

OpenSSL是什么：众多的密码算法、公钥基础设施标准以及SSL协议，或许这些有趣的功能会让你产生实现所有这些算法和标准的想法。果真如此，在对你表示敬佩的同时，还是忍不住提醒你：这是一个令人望而生畏的过程。这个工作不再是简单的读懂几本密码学专著和协议文档那么简单，而是要理解所有这些算法、标准和协议文档的每一个细节，并用你可能很熟悉的C语言字符一个一个去实现这些定义和过程。我们不知道你将需要多少时间来完成这项有趣而可怕的工作，但肯定不是一年两年的问题。OpenSSL就是由Eric A. Young和Tim J. Hudson两位绝世大好人自1995年就开始编写的集合众多安全算法的算法集合。通过命令或者开发库，我们可以轻松实现标准的公开算法应用。

下面将介绍如何生成和使用秘钥。

一、使用OpenSSL来生成私钥和公钥

先验证系统上是否已经安装OpenSSL工具，Linux系统默认安装，但Windows默认没安装，需自行下载安装。请参考：Windows安装openssl

λ openssl.exe version -a                              
OpenSSL 1.1.0e  16 Feb 2017                           
built on: reproducible build, date unspecified        
platform:                                             
compiler: cl " "VC-WIN64A                             
OPENSSLDIR: "C:\\Program Files\\Common Files\\SSL"       
ENGINESDIR: "C:\\Program Files\\OpenSSL\\lib\\engines-1_1"

先来生成私钥：

λ openssl genrsa -out rsa_private_key.pem 1024   
Generating RSA private key, 1024 bit long modulus
....................................++++++       
........++++++                                   
e is 65537 (0x010001)                            

这条命令让openssl随机生成了一份私钥，加密长度是1024位。加密长度是指理论上最大允许”被加密的信息“长度的限制，也就是明文的长度限制。随着这个参数的增大（比方说2048），允许的明文长度也会增加，但同时也会造成计算复杂度的极速增长。一般推荐的长度就是1024位（128字节）。

 

我们来看一下私钥的内容：

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

内容都是标准的ASCII字符，开头一行和结尾一行有明显的标记，真正的私钥数据是中间的不规则字符。

密钥文件最终将数据通过Base64编码进行存储。可以看到上述密钥文件内容每一行的长度都很规律。这是由于RFC2045中规定：The encoded output stream must be represented in lines of no more than 76 characters each。也就是说Base64编码的数据每行最多不超过76字符，对于超长数据需要按行分割。

接下来根据私钥生成公钥：

λ openssl rsa -in rsa_private_key.pem -out rsa_public_key.pem -pubout
writing RSA key

再来看一下公钥的内容：

-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDKeYC1p4iE7koV4JOlr+doVwIy
hcI3q+q/MkBtPPN/w4J/2h3ULqaKXb54Fs8ON9rDFEVLShtbxX6fYx3vBEArrd51
6KWYYcx5la1vr1KHFtJScN/p3u0vwSj7ElE8U7aZwtkXL7iqGGLOyM1wQNqyIMi7
nayPeOP2RzSYy2uUQQIDAQAB
-----END PUBLIC KEY-----

这时候的私钥还不能直接被使用，需要进行PKCS#8编码：

λ openssl pkcs8 -topk8 -in rsa_private_key.pem -out pkcs8_rsa_private_key.pem -nocrypt

命令中指明了输入私钥文件为rsa_private_key.pem，输出私钥文件为pkcs8_rsa_private_key.pem，不采用任何二次加密（-nocrypt）

 如果不进行PKCS#8编码，Java在使用时会报错：

java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : algid parse error, not a sequence

 

再来看一下，编码后的私钥文件是不是和之前的私钥文件不同了：

-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----

至此，可用的密钥对已经生成好了，私钥使用pkcs8_rsa_private_key.pem，公钥采用rsa_public_key.pem。

最近又遇到RSA加密的需求了，而且对方要求只能使用第一步生成的未经过PKCS#8编码的私钥文件。后来查看相关文献得知第一步生成的私钥文件编码是PKCS#1格式，这种格式Java其实是支持的，只不过多写两行代码而已：

RSAPrivateKeyStructure asn1PrivKey = new RSAPrivateKeyStructure((ASN1Sequence) ASN1Sequence.fromByteArray(priKeyData));  
RSAPrivateKeySpec rsaPrivKeySpec = new RSAPrivateKeySpec(asn1PrivKey.getModulus(), asn1PrivKey.getPrivateExponent());  
KeyFactory keyFactory= KeyFactory.getInstance("RSA");  
PrivateKey priKey= keyFactory.generatePrivate(rsaPrivKeySpec); 

首先将PKCS#1的私钥文件读取出来（注意去掉减号开头的注释内容），然后使用Base64解码读出的字符串，便得到priKeyData，也就是第一行代码中的参数。最后一行得到了私钥。接下来的用法就没什么区别了。

二、编写Java代码实际测试

RSA加密解密类：

  1 import java.io.BufferedReader;
  2 import java.io.BufferedWriter;
  3 import java.io.FileReader;
  4 import java.io.FileWriter;
  5 import java.io.IOException;
  6 import java.security.InvalidKeyException;
  7 import java.security.KeyFactory;
  8 import java.security.KeyPair;
  9 import java.security.KeyPairGenerator;
 10 import java.security.NoSuchAlgorithmException;
 11 import java.security.SecureRandom;
 12 
 13 import java.security.interfaces.RSAPrivateKey;
 14 import java.security.interfaces.RSAPublicKey;
 15 import java.security.spec.InvalidKeySpecException;
 16 import java.security.spec.PKCS8EncodedKeySpec;
 17 import java.security.spec.X509EncodedKeySpec;
 18 
 19 import javax.crypto.BadPaddingException;
 20 import javax.crypto.Cipher;
 21 import javax.crypto.IllegalBlockSizeException;
 22 import javax.crypto.NoSuchPaddingException;
 23 
 24 import org.apache.commons.codec.binary.Base64;
 25 
 26 public class RSAEncrypt {
 27     /**
 28      * 字节数据转字符串专用集合
 29      */
 30     private static final char[] HEX_CHAR = { ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘,
 31             ‘7‘, ‘8‘, ‘9‘, ‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘ };
 32 
 33     /**
 34      * 随机生成密钥对
 35      */
 36     public static void genKeyPair(String filePath) {
 37         // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
 38         KeyPairGenerator keyPairGen = null;
 39         try {
 40             keyPairGen = KeyPairGenerator.getInstance("RSA");
 41         } catch (NoSuchAlgorithmException e) {
 42             e.printStackTrace();
 43         }
 44         // 初始化密钥对生成器，密钥大小为96-1024位
 45         keyPairGen.initialize(1024,new SecureRandom());
 46         // 生成一个密钥对，保存在keyPair中
 47         KeyPair keyPair = keyPairGen.generateKeyPair();
 48         // 得到私钥
 49         RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
 50         // 得到公钥
 51         RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
 52         try {
 53             // 得到公钥字符串
 54             Base64 base64 = new Base64();
 55             String publicKeyString = new String(base64.encode(publicKey.getEncoded()));
 56             // 得到私钥字符串
 57             String privateKeyString = new String(base64.encode(privateKey.getEncoded()));
 58             // 将密钥对写入到文件
 59             FileWriter pubfw = new FileWriter(filePath + "/publicKey.keystore");
 60             FileWriter prifw = new FileWriter(filePath + "/privateKey.keystore");
 61             BufferedWriter pubbw = new BufferedWriter(pubfw);
 62             BufferedWriter pribw = new BufferedWriter(prifw);
 63             pubbw.write(publicKeyString);
 64             pribw.write(privateKeyString);
 65             pubbw.flush();
 66             pubbw.close();
 67             pubfw.close();
 68             pribw.flush();
 69             pribw.close();
 70             prifw.close();
 71         } catch (Exception e) {
 72             e.printStackTrace();
 73         }
 74     }
 75 
 76     /**
 77      * 从文件中输入流中加载公钥
 78      * 
 79      * @param in
 80      *            公钥输入流
 81      * @throws Exception
 82      *             加载公钥时产生的异常
 83      */
 84     public static String loadPublicKeyByFile(String path) throws Exception {
 85         try {
 86             BufferedReader br = new BufferedReader(new FileReader(path
 87                     + "/publicKey.keystore"));
 88             String readLine = null;
 89             StringBuilder sb = new StringBuilder();
 90             while ((readLine = br.readLine()) != null) {
 91                 sb.append(readLine);
 92             }
 93             br.close();
 94             return sb.toString();
 95         } catch (IOException e) {
 96             throw new Exception("公钥数据流读取错误");
 97         } catch (NullPointerException e) {
 98             throw new Exception("公钥输入流为空");
 99         }
100     }
101 
102     /**
103      * 从字符串中加载公钥
104      * 
105      * @param publicKeyStr
106      *            公钥数据字符串
107      * @throws Exception
108      *             加载公钥时产生的异常
109      */
110     public static RSAPublicKey loadPublicKeyByStr(String publicKeyStr)
111             throws Exception {
112         try {
113             Base64 base64 = new Base64();
114             byte[] buffer = base64.decode(publicKeyStr);
115             KeyFactory keyFactory = KeyFactory.getInstance("RSA");
116             X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
117             return (RSAPublicKey) keyFactory.generatePublic(keySpec);
118         } catch (NoSuchAlgorithmException e) {
119             throw new Exception("无此算法");
120         } catch (InvalidKeySpecException e) {
121             throw new Exception("公钥非法");
122         } catch (NullPointerException e) {
123             throw new Exception("公钥数据为空");
124         }
125     }
126 
127     /**
128      * 从文件中加载私钥
129      * 
130      * @param keyFileName
131      *            私钥文件名
132      * @return 是否成功
133      * @throws Exception
134      */
135     public static String loadPrivateKeyByFile(String path) throws Exception {
136         try {
137             BufferedReader br = new BufferedReader(new FileReader(path
138                     + "/privateKey.keystore"));
139             String readLine = null;
140             StringBuilder sb = new StringBuilder();
141             while ((readLine = br.readLine()) != null) {
142                 sb.append(readLine);
143             }
144             br.close();
145             return sb.toString();
146         } catch (IOException e) {
147             throw new Exception("私钥数据读取错误");
148         } catch (NullPointerException e) {
149             throw new Exception("私钥输入流为空");
150         }
151     }
152 
153     public static RSAPrivateKey loadPrivateKeyByStr(String privateKeyStr)
154             throws Exception {
155         try {
156             Base64 base64 = new Base64();
157             byte[] buffer = base64.decode(privateKeyStr);
158             PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
159             KeyFactory keyFactory = KeyFactory.getInstance("RSA");
160             return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
161         } catch (NoSuchAlgorithmException e) {
162             throw new Exception("无此算法");
163         } catch (InvalidKeySpecException e) {
164             throw new Exception("私钥非法");
165         } catch (NullPointerException e) {
166             throw new Exception("私钥数据为空");
167         }
168     }
169 
170     /**
171      * 公钥加密过程
172      * 
173      * @param publicKey
174      *            公钥
175      * @param plainTextData
176      *            明文数据
177      * @return
178      * @throws Exception
179      *             加密过程中的异常信息
180      */
181     public static byte[] encrypt(RSAPublicKey publicKey, byte[] plainTextData)
182             throws Exception {
183         if (publicKey == null) {
184             throw new Exception("加密公钥为空, 请设置");
185         }
186         Cipher cipher = null;
187         try {
188             // 使用默认RSA
189             cipher = Cipher.getInstance("RSA");
190             // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
191             cipher.init(Cipher.ENCRYPT_MODE, publicKey);
192             byte[] output = cipher.doFinal(plainTextData);
193             return output;
194         } catch (NoSuchAlgorithmException e) {
195             throw new Exception("无此加密算法");
196         } catch (NoSuchPaddingException e) {
197             e.printStackTrace();
198             return null;
199         } catch (InvalidKeyException e) {
200             throw new Exception("加密公钥非法,请检查");
201         } catch (IllegalBlockSizeException e) {
202             throw new Exception("明文长度非法");
203         } catch (BadPaddingException e) {
204             throw new Exception("明文数据已损坏");
205         }
206     }
207 
208     /**
209      * 私钥加密过程
210      * 
211      * @param privateKey
212      *            私钥
213      * @param plainTextData
214      *            明文数据
215      * @return
216      * @throws Exception
217      *             加密过程中的异常信息
218      */
219     public static byte[] encrypt(RSAPrivateKey privateKey, byte[] plainTextData)
220             throws Exception {
221         if (privateKey == null) {
222             throw new Exception("加密私钥为空, 请设置");
223         }
224         Cipher cipher = null;
225         try {
226             // 使用默认RSA
227             cipher = Cipher.getInstance("RSA");
228             cipher.init(Cipher.ENCRYPT_MODE, privateKey);
229             byte[] output = cipher.doFinal(plainTextData);
230             return output;
231         } catch (NoSuchAlgorithmException e) {
232             throw new Exception("无此加密算法");
233         } catch (NoSuchPaddingException e) {
234             e.printStackTrace();
235             return null;
236         } catch (InvalidKeyException e) {
237             throw new Exception("加密私钥非法,请检查");
238         } catch (IllegalBlockSizeException e) {
239             throw new Exception("明文长度非法");
240         } catch (BadPaddingException e) {
241             throw new Exception("明文数据已损坏");
242         }
243     }
244 
245     /**
246      * 私钥解密过程
247      * 
248      * @param privateKey
249      *            私钥
250      * @param cipherData
251      *            密文数据
252      * @return 明文
253      * @throws Exception
254      *             解密过程中的异常信息
255      */
256     public static byte[] decrypt(RSAPrivateKey privateKey, byte[] cipherData)
257             throws Exception {
258         if (privateKey == null) {
259             throw new Exception("解密私钥为空, 请设置");
260         }
261         Cipher cipher = null;
262         try {
263             // 使用默认RSA
264             cipher = Cipher.getInstance("RSA");
265             // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
266             cipher.init(Cipher.DECRYPT_MODE, privateKey);
267             byte[] output = cipher.doFinal(cipherData);
268             return output;
269         } catch (NoSuchAlgorithmException e) {
270             throw new Exception("无此解密算法");
271         } catch (NoSuchPaddingException e) {
272             e.printStackTrace();
273             return null;
274         } catch (InvalidKeyException e) {
275             throw new Exception("解密私钥非法,请检查");
276         } catch (IllegalBlockSizeException e) {
277             throw new Exception("密文长度非法");
278         } catch (BadPaddingException e) {
279             throw new Exception("密文数据已损坏");
280         }
281     }
282 
283     /**
284      * 公钥解密过程
285      * 
286      * @param publicKey
287      *            公钥
288      * @param cipherData
289      *            密文数据
290      * @return 明文
291      * @throws Exception
292      *             解密过程中的异常信息
293      */
294     public static byte[] decrypt(RSAPublicKey publicKey, byte[] cipherData)
295             throws Exception {
296         if (publicKey == null) {
297             throw new Exception("解密公钥为空, 请设置");
298         }
299         Cipher cipher = null;
300         try {
301             // 使用默认RSA
302             cipher = Cipher.getInstance("RSA");
303             // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
304             cipher.init(Cipher.DECRYPT_MODE, publicKey);
305             byte[] output = cipher.doFinal(cipherData);
306             return output;
307         } catch (NoSuchAlgorithmException e) {
308             throw new Exception("无此解密算法");
309         } catch (NoSuchPaddingException e) {
310             e.printStackTrace();
311             return null;
312         } catch (InvalidKeyException e) {
313             throw new Exception("解密公钥非法,请检查");
314         } catch (IllegalBlockSizeException e) {
315             throw new Exception("密文长度非法");
316         } catch (BadPaddingException e) {
317             throw new Exception("密文数据已损坏");
318         }
319     }
320 
321     /**
322      * 字节数据转十六进制字符串
323      * 
324      * @param data
325      *            输入数据
326      * @return 十六进制内容
327      */
328     public static String byteArrayToString(byte[] data) {
329         StringBuilder stringBuilder = new StringBuilder();
330         for (int i = 0; i < data.length; i++) {
331             // 取出字节的高四位 作为索引得到相应的十六进制标识符 注意无符号右移
332             stringBuilder.append(HEX_CHAR[(data[i] & 0xf0) >>> 4]);
333             // 取出字节的低四位 作为索引得到相应的十六进制标识符
334             stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);
335             if (i < data.length - 1) {
336                 stringBuilder.append(‘ ‘);
337             }
338         }
339         return stringBuilder.toString();
340     }
341 }

签名及校验类：

  1 import java.security.KeyFactory;
  2 import java.security.PrivateKey;
  3 import java.security.PublicKey;
  4 import java.security.spec.PKCS8EncodedKeySpec;
  5 import java.security.spec.X509EncodedKeySpec;
  6 
  7 import org.apache.commons.codec.binary.Base64;
  8 
  9 /**
 10  * RSA签名验签类
 11  */
 12 public class RSASignature {
 13 
 14     /**
 15      * 签名算法
 16      */
 17     public static final String SIGN_ALGORITHMS = "SHA1WithRSA";
 18 
 19     /**
 20      * RSA签名
 21      * 
 22      * @param content
 23      *            待签名数据
 24      * @param privateKey
 25      *            商户私钥
 26      * @param encode
 27      *            字符集编码
 28      * @return 签名值
 29      */
 30     public static String sign(String content, String privateKey, String encode) {
 31         try {
 32             Base64 base64 = new Base64();
 33             PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(base64.decode(privateKey));
 34 
 35             KeyFactory keyf = KeyFactory.getInstance("RSA");
 36             PrivateKey priKey = keyf.generatePrivate(priPKCS8);
 37 
 38             java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
 39 
 40             signature.initSign(priKey);
 41             signature.update(content.getBytes(encode));
 42 
 43             byte[] signed = signature.sign();
 44 
 45             return new String(base64.encode(signed));
 46         } catch (Exception e) {
 47             e.printStackTrace();
 48         }
 49 
 50         return null;
 51     }
 52 
 53     public static String sign(String content, String privateKey) {
 54         try {
 55             Base64 base64 = new Base64();
 56             PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(base64.decode(privateKey));
 57             KeyFactory keyf = KeyFactory.getInstance("RSA");
 58             PrivateKey priKey = keyf.generatePrivate(priPKCS8);
 59             java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
 60             signature.initSign(priKey);
 61             signature.update(content.getBytes());
 62             byte[] signed = signature.sign();
 63             return new String(base64.encode(signed));
 64         } catch (Exception e) {
 65             e.printStackTrace();
 66         }
 67         return null;
 68     }
 69 
 70     /**
 71      * RSA验签名检查
 72      * 
 73      * @param content
 74      *            待签名数据
 75      * @param sign
 76      *            签名值
 77      * @param publicKey
 78      *            分配给开发商公钥
 79      * @param encode
 80      *            字符集编码
 81      * @return 布尔值
 82      */
 83     public static boolean doCheck(String content, String sign, String publicKey, String encode) {
 84         try {
 85             KeyFactory keyFactory = KeyFactory.getInstance("RSA");
 86             Base64 base64 = new Base64();
 87             byte[] encodedKey = base64.decode(publicKey);
 88             PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
 89 
 90             java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
 91 
 92             signature.initVerify(pubKey);
 93             signature.update(content.getBytes(encode));
 94 
 95             boolean bverify = signature.verify(base64.decode(sign));
 96             return bverify;
 97 
 98         } catch (Exception e) {
 99             e.printStackTrace();
100         }
101 
102         return false;
103     }
104 
105     public static boolean doCheck(String content, String sign, String publicKey) {
106         try {
107             KeyFactory keyFactory = KeyFactory.getInstance("RSA");
108             Base64 base64 = new Base64();
109             byte[] encodedKey = base64.decode(publicKey);
110             PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
111 
112             java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
113 
114             signature.initVerify(pubKey);
115             signature.update(content.getBytes());
116 
117             boolean bverify = signature.verify(base64.decode(sign));
118             return bverify;
119 
120         } catch (Exception e) {
121             e.printStackTrace();
122         }
123 
124         return false;
125     }
126 
127 }

最后是一个MainTest：

 1 import org.apache.commons.codec.binary.Base64;
 2 
 3 public class MainTest {
 4 
 5     public static void main(String[] args) throws Exception {
 6         String filepath = "G:/tmp/";
 7 
 8         // RSAEncrypt.genKeyPair(filepath);
 9 
10         Base64 base64 = new Base64();
11 
12         System.out.println("--------------公钥加密私钥解密过程-------------------");
13         String plainText = "ihep_公钥加密私钥解密";
14         // 公钥加密过程
15         byte[] cipherData = RSAEncrypt.encrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)),
16                 plainText.getBytes());
17         String cipher = new String(base64.encode(cipherData));
18         // 私钥解密过程
19         byte[] res = RSAEncrypt.decrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)),
20                 base64.decode(cipher));
21         String restr = new String(res);
22         System.out.println("原文：" + plainText);
23         System.out.println("加密：" + cipher);
24         System.out.println("解密：" + restr);
25         System.out.println();
26 
27         System.out.println("--------------私钥加密公钥解密过程-------------------");
28         plainText = "ihep_私钥加密公钥解密";
29         // 私钥加密过程
30         cipherData = RSAEncrypt.encrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)),
31                 plainText.getBytes());
32         cipher = new String(base64.encode(cipherData));
33         // 公钥解密过程
34         res = RSAEncrypt.decrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)),
35                 base64.decode(cipher));
36         restr = new String(res);
37         System.out.println("原文：" + plainText);
38         System.out.println("加密：" + cipher);
39         System.out.println("解密：" + restr);
40         System.out.println();
41 
42         System.out.println("---------------私钥签名过程------------------");
43         String content = "ihep_这是用于签名的原始数据";
44         String signstr = RSASignature.sign(content, RSAEncrypt.loadPrivateKeyByFile(filepath));
45         System.out.println("签名原串：" + content);
46         System.out.println("签名串：" + signstr);
47         System.out.println();
48 
49         System.out.println("---------------公钥校验签名------------------");
50         System.out.println("签名原串：" + content);
51         System.out.println("签名串：" + signstr);
52 
53         System.out.println("验签结果：" + RSASignature.doCheck(content, signstr, RSAEncrypt.loadPublicKeyByFile(filepath)));
54         System.out.println();
55 
56     }
57 }

 

参考：

http://blog.csdn.net/chaijunkun/article/details/7275632

http://blog.csdn.net/wangqiuyun/article/details/42143957