RSA 数据加密解密

 下述代码中：PUBLIC_KEY 和 PRIVATE_KEY 可自己生成后替换即可。

1package com.bing.security.util;
2
3
4
5import org.apache.commons.codec.binary.Hex;
6
7import javax.crypto.Cipher;
8import java.io.ByteArrayOutputStream;
9import java.security.*;
10import java.security.spec.PKCS8EncodedKeySpec;
11import java.security.spec.X509EncodedKeySpec;
12import java.util.Base64;
13
14/**
15 * @package：com.bing.security.util
16 * @des： 数据加密解密工具类
17 * @autor ：Ryan Wang
18 * @createTime： 2018/2/9-11:29
19 */
20public class SecurityUtil {
21
22    /**
23     * 对数据加密生成16进制字符串
24     * @param data 要处理的字符串
25     */
26    public static String encryptDataAsHex(String data) {
27        byte[] bytes = encryptData(data);
28        return Hex.encodeHexString(bytes).toUpperCase();
29    }
30
31    /**
32     * 对数据加密并进行Base64转码
33     * @param data 要处理的字符串
34     */
35    public static String encryptDataAsEncode(String data) {
36        byte[] bytes = encryptData(data);
37        return Base64.getEncoder().encodeToString(bytes);
38    }
39
40    /**
41     * 将16进制的字符串进行解密
42     * @param data
43     */
44    public static String decryptDataFromHex(String data) {
45        if (data == null) {
46            return "";
47        }
48        byte[] encryptData = hexStringToBytes(data);
49        return new String(decryptData(encryptData));
50    }
51
52    /**
53     * 将base64编码的字符串进行解密
54     * @param data
55     */
56    public static String decryptDataFromEncode(String data) {
57        if (data == null) {
58            return "";
59        }
60        byte[] encryptData = Base64.getDecoder().decode(data);
61        return new String(decryptData(encryptData));
62    }
63
64    private static byte[] decryptData(byte[] encryptData) {
65        ByteArrayOutputStream outputStream = null;
66        try {
67            Cipher cipher = Cipher.getInstance("RSA");
68            cipher.init(Cipher.DECRYPT_MODE, getPrivateKey());
69            int length = encryptData.length;
70            int offset = 0;
71            int i = 0;
72            byte[] cache;
73            outputStream = new ByteArrayOutputStream();
74            while (length - offset > 0) {
75                /*最大解密字节长度*/
76                Integer MAX_DECRYPT_BLOCK = 128;
77                if (length - offset > MAX_DECRYPT_BLOCK) {
78                    cache = cipher.doFinal(encryptData, offset, MAX_DECRYPT_BLOCK);
79                } else {
80                    cache = cipher.doFinal(encryptData, offset, length - offset);
81                }
82                outputStream.write(cache, 0, cache.length);
83                offset = (++i) * MAX_DECRYPT_BLOCK;
84            }
85            outputStream.close();
86        } catch (Exception e) {
87            e.printStackTrace();
88        }
89        return outputStream != null ? outputStream.toByteArray() : new byte[0];
90    }
91
92    private static byte[] encryptData(String data) {
93        if (data == null) {
94            return new byte[0];
95        }
96        ByteArrayOutputStream outputStream;
97        try {
98            Cipher cipher = Cipher.getInstance("RSA");
99            cipher.init(Cipher.ENCRYPT_MODE, getPublicKey());
100            int length = data.getBytes().length;
101            int offset = 0;
102            int i = 0;
103            byte[] cache;
104            outputStream = new ByteArrayOutputStream();
105            while (length - offset > 0) {
106                /*最大加密字节长度*/
107                Integer MAX_ENCRYPT_BLOCK = 117;
108                if (length - offset > MAX_ENCRYPT_BLOCK) {
109                    cache = cipher.doFinal(data.getBytes(), offset, MAX_ENCRYPT_BLOCK);
110                } else {
111                    cache = cipher.doFinal(data.getBytes(), offset, length - offset);
112                }
113                outputStream.write(cache, 0, cache.length);
114                offset = (++i) * MAX_ENCRYPT_BLOCK;
115            }
116            outputStream.close();
117        } catch (Exception e) {
118            return new byte[0];
119        }
120        return outputStream.toByteArray();
121    }
122
123    /**
124     * 将16进制的字符串转为byte[]
125     * @param hexString
126     */
127    private static byte[] hexStringToBytes(String hexString) {
128        if (hexString == null) {
129            return null;
130        }
131        hexString = hexString.toUpperCase();
132        int length = hexString.length() / 2;
133        char[] hexChars = hexString.toCharArray();
134        byte[] bytes = new byte[length];
135        for (int i =0;i<length;i++) {
136            int pos = i * 2;
137            bytes[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
138        }
139        return bytes;
140    }
141
142    private static byte charToByte(char c) {
143        return (byte) "0123456789ABCDEF".indexOf(c);
144    }
145
146    /**
147     * 获取RSA public key
148     */
149    private static PublicKey getPublicKey() throws Exception {
150        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(Constant.PUBLIC_KEY_STR));
151        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
152        return keyFactory.generatePublic(keySpec);
153    }
154
155    /**
156     * 获取RSA private key
157     */
158    private static PrivateKey getPrivateKey() throws Exception {
159        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(Constant.PRIVATE_KEY_STR));
160        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
161        return keyFactory.generatePrivate(keySpec);
162    }
163}