RSA密钥的数据类型转换：由合法的string到PublicKey或PrivateKey
RSA密钥的数据类型转换：由合法的string到PublicKey或PrivateKey
给定base64编码的RSA公钥和私钥，下面两段代码可以将string类型转换为PublicKey和PrivateKey类型，后面会给出完整的测试程序。至于如何将其他形式（如16进制编码string或byte之类的）转换为base64 string就很简单了，可以使用Base64那个库，自己下个jar包，里面有encode和decode之类的方法，hex转base64网上也可以搜到。
转换代码如下：
public static PublicKey getPublicKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = (new BASE64Decoder()).decodeBuffer(key);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(keySpec);
return publicKey;
}
public static PrivateKey getPrivateKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = (new BASE64Decoder()).decodeBuffer(key);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
return privateKey;
}
注意：不是随便敲一串字母就可以作为密钥string使用的，需要用严格的代码生成公钥串和私钥串。
完整的程序如下：
程序中包含密钥转换、加密和签名三个部分。
1 package pack1;
2
3 import java.security.Key;
4 import java.security.KeyFactory;
5 import java.security.KeyPair;
6 import java.security.KeyPairGenerator;
7 import java.security.PrivateKey;
8 import java.security.PublicKey;
9 import java.security.Signature;
10 import java.security.interfaces.RSAPrivateKey;
11 import java.security.interfaces.RSAPublicKey;
12 import java.security.spec.PKCS8EncodedKeySpec;
13 import java.security.spec.X509EncodedKeySpec;
14
15 import javax.crypto.Cipher;
16
17 import org.apache.commons.codec.binary.Base64;
18
19 import sun.misc.BASE64Decoder;
20 import sun.misc.BASE64Encoder;
21
22
23 public class RSAtest{
24 public static final String KEY_ALGORITHM="RSA";
25 public static final String SIGNATURE_ALGORITHM="MD5withRSA";
26 private static final int KEY_SIZE=1024;
27 private static final String PUBLIC_KEY="RSAPublicKey";
28 private static final String PRIVATE_KEY="RSAPrivateKey";
29 public static String str_pubK = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCqPvovSfXcwBbW8cKMCgwqNpsYuzF8RPAPFb7LGsnVo44JhM/xxzDyzoYtdfNmtbIuKVi9PzIsyp6rg+09gbuI6UGwBZ5DWBDBMqv5MPdOF5dCQkB2Bbr5yPfURPENypUz+pBFBg41d+BC+rwRiXELwKy7Y9caD/MtJyHydj8OUwIDAQAB";
30 public static String str_priK = "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";
31 /**
32 * 使用getPublicKey得到公钥,返回类型为PublicKey
33 * @param base64 String to PublicKey
34 * @throws Exception
35 */
36 public static PublicKey getPublicKey(String key) throws Exception {
37 byte[] keyBytes;
38 keyBytes = (new BASE64Decoder()).decodeBuffer(key);
39 X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
40 KeyFactory keyFactory = KeyFactory.getInstance("RSA");
41 PublicKey publicKey = keyFactory.generatePublic(keySpec);
42 return publicKey;
43 }
44 /**
45 * 转换私钥
46 * @param base64 String to PrivateKey
47 * @throws Exception
48 */
49 public static PrivateKey getPrivateKey(String key) throws Exception {
50 byte[] keyBytes;
51 keyBytes = (new BASE64Decoder()).decodeBuffer(key);
52 PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
53 KeyFactory keyFactory = KeyFactory.getInstance("RSA");
54 PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
55 return privateKey;
56 }
57
58 //***************************签名和验证*******************************
59 public static byte[] sign(byte[] data) throws Exception{
60 PrivateKey priK = getPrivateKey(str_priK);
61 Signature sig = Signature.getInstance(SIGNATURE_ALGORITHM);
62 sig.initSign(priK);
63 sig.update(data);
64 return sig.sign();
65 }
66
67 public static boolean verify(byte[] data,byte[] sign) throws Exception{
68 PublicKey pubK = getPublicKey(str_pubK);
69 Signature sig = Signature.getInstance(SIGNATURE_ALGORITHM);
70 sig.initVerify(pubK);
71 sig.update(data);
72 return sig.verify(sign);
73 }
74
75 //************************加密解密**************************
76 public static byte[] encrypt(byte[] bt_plaintext)throws Exception{
77 PublicKey publicKey = getPublicKey(str_pubK);
78 Cipher cipher = Cipher.getInstance("RSA");
79 cipher.init(Cipher.ENCRYPT_MODE, publicKey);
80 byte[] bt_encrypted = cipher.doFinal(bt_plaintext);
81 return bt_encrypted;
82 }
83
84 public static byte[] decrypt(byte[] bt_encrypted)throws Exception{
85 PrivateKey privateKey = getPrivateKey(str_priK);
86 Cipher cipher = Cipher.getInstance("RSA");
87 cipher.init(Cipher.DECRYPT_MODE, privateKey);
88 byte[] bt_original = cipher.doFinal(bt_encrypted);
89 return bt_original;
90 }
91 //********************main函数：加密解密和签名验证*********************
92 public static void main(String[] args) throws Exception {
93 String str_plaintext = "这是一段用来测试密钥转换的明文";
94 System.err.println("明文："+str_plaintext);
95 byte[] bt_cipher = encrypt(str_plaintext.getBytes());
96 System.out.println("加密后："+Base64.encodeBase64String(bt_cipher));
97
98 byte[] bt_original = decrypt(bt_cipher);
99 String str_original = new String(bt_original);
100 System.out.println("解密结果:"+str_original);
101
102 String str="被签名的内容";
103 System.err.println("\n原文:"+str);
104 byte[] signature=sign(str.getBytes());
105 System.out.println("产生签名："+Base64.encodeBase64String(signature));
106 boolean status=verify(str.getBytes(), signature);
107 System.out.println("验证情况："+status);
108 }
109
110 }
曾经在百度知道上寻求过这个问题，一直都没能很好的解决。今日coding测试成功，来分享一下，技术有限，不足之处望指正。。。。。。by SHADOW.Delta