Skip to content

Commit a75d87c

Browse files
codingWangcodingWang
committed
java encrypt
1 parent 13d1947 commit a75d87c

File tree

9 files changed

+298
-0
lines changed

9 files changed

+298
-0
lines changed

‎bin/com/duwei/encrypt/FrequencyAnalysis$1.class

1.34 KB
Binary file not shown.

‎bin/com/duwei/encrypt/FrequencyAnalysis.class

5.62 KB
Binary file not shown.

‎bin/com/duwei/encrypt/MessageDigestTest.class

1.02 KB
Binary file not shown.

‎bin/com/duwei/encrypt/MyEncrypt.class

1.01 KB
Binary file not shown.

‎bin/com/duwei/encrypt/RSA.class

1.56 KB
Binary file not shown.

‎src/com/duwei/encrypt/FrequencyAnalysis.java

Lines changed: 154 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,154 @@
1+
package com.duwei.encrypt;
2+
3+
import java.io.File;
4+
import java.io.FileReader;
5+
import java.io.FileWriter;
6+
import java.io.IOException;
7+
import java.util.ArrayList;
8+
import java.util.Collections;
9+
import java.util.Comparator;
10+
import java.util.HashMap;
11+
import java.util.List;
12+
import java.util.Map;
13+
import java.util.Map.Entry;
14+
15+
/**
16+
* 频率分析法破解凯撒密码
17+
* http://blog.csdn.net/axi295309066/article/details/52491077
18+
*/
19+
public class FrequencyAnalysis {
20+
//英文里出现次数最多的字符
21+
private static final char MAGIC_CHAR = 'e';
22+
//破解生成的最大文件数
23+
private static final int DE_MAX_FILE = 4;
24+
25+
public static void main(String[] args) throws Exception {
26+
//测试1，统计字符个数
27+
//printCharCount("article1_en.txt");
28+
29+
//加密文件
30+
//int key = 3;
31+
//encryptFile("article1.txt", "article1_en.txt", key);
32+
33+
//读取加密后的文件
34+
String artile = file2String("article1_en.txt");
35+
//解密（会生成多个备选文件）
36+
decryptCaesarCode(artile, "article1_de.txt");
37+
}
38+
39+
public static void printCharCount(String path) throws IOException{
40+
String data = file2String(path);
41+
List<Entry<Character, Integer>> mapList = getMaxCountChar(data);
42+
for (Entry<Character, Integer> entry : mapList) {
43+
//输出前几位的统计信息
44+
System.out.println("字符'" + entry.getKey() + "'出现" + entry.getValue() + "次");
45+
}
46+
}
47+
48+
public static void encryptFile(String srcFile, String destFile, int key) throws IOException {
49+
String artile = file2String(srcFile);
50+
//加密文件
51+
String encryptData = MyEncrypt.encrypt(artile, key);
52+
//保存加密后的文件
53+
string2File(encryptData, destFile);
54+
}
55+
56+
/**
57+
* 破解凯撒密码
58+
* @param input 数据源
59+
* @return 返回解密后的数据
60+
*/
61+
public static void decryptCaesarCode(String input, String destPath) {
62+
int deCount = 0;//当前解密生成的备选文件数
63+
//获取出现频率最高的字符信息（出现次数越多越靠前）
64+
List<Entry<Character, Integer>> mapList = getMaxCountChar(input);
65+
for (Entry<Character, Integer> entry : mapList) {
66+
//限制解密文件备选数
67+
if (deCount >= DE_MAX_FILE) {
68+
break;
69+
}
70+
71+
//输出前几位的统计信息
72+
System.out.println("字符'" + entry.getKey() + "'出现" + entry.getValue() + "次");
73+
74+
++deCount;
75+
//出现次数最高的字符跟MAGIC_CHAR的偏移量即为秘钥
76+
int key = entry.getKey() - MAGIC_CHAR;
77+
System.out.println("猜测key = " + key + "， 解密生成第" + deCount + "个备选文件" + "\n");
78+
String decrypt = MyEncrypt.decrypt(input, key);
79+
80+
String fileName = "de_" + deCount + destPath;
81+
string2File(decrypt, fileName);
82+
}
83+
}
84+
85+
//统计String里出现最多的字符
86+
public static List<Entry<Character, Integer>> getMaxCountChar(String data) {
87+
Map<Character, Integer> map = new HashMap<Character, Integer>();
88+
char[] array = data.toCharArray();
89+
for (char c : array) {
90+
if(!map.containsKey(c)) {
91+
map.put(c, 1);
92+
}else{
93+
Integer count = map.get(c);
94+
map.put(c, count + 1);
95+
}
96+
}
97+
98+
//输出统计信息
99+
/*for (Entry<Character, Integer> entry : map.entrySet()) {
100+
System.out.println(entry.getKey() + "出现" + entry.getValue() + "次");
101+
}*/
102+
103+
//获取获取最大值
104+
int maxCount = 0;
105+
for (Entry<Character, Integer> entry : map.entrySet()) {
106+
//不统计空格
107+
if (/*entry.getKey() != ' ' && */entry.getValue() > maxCount) {
108+
maxCount = entry.getValue();
109+
}
110+
}
111+
112+
//map转换成list便于排序
113+
List<Entry<Character, Integer>> mapList = new ArrayList<Map.Entry<Character,Integer>>(map.entrySet());
114+
//根据字符出现次数排序
115+
Collections.sort(mapList, new Comparator<Entry<Character, Integer>>(){
116+
@Override
117+
public int compare(Entry<Character, Integer> o1,
118+
Entry<Character, Integer> o2) {
119+
return o2.getValue().compareTo(o1.getValue());
120+
}
121+
});
122+
return mapList;
123+
}
124+
125+
public static String file2String(String path) throws IOException {
126+
FileReader reader = new FileReader(new File(path));
127+
char[] buffer = new char[1024];
128+
int len = -1;
129+
StringBuffer sb = new StringBuffer();
130+
while ((len = reader.read(buffer)) != -1) {
131+
sb.append(buffer, 0, len);
132+
}
133+
return sb.toString();
134+
}
135+
136+
public static void string2File(String data, String path){
137+
FileWriter writer = null;
138+
try {
139+
writer = new FileWriter(new File(path));
140+
writer.write(data);
141+
} catch (Exception e) {
142+
e.printStackTrace();
143+
}finally {
144+
if (writer != null) {
145+
try {
146+
writer.close();
147+
} catch (IOException e) {
148+
e.printStackTrace();
149+
}
150+
}
151+
}
152+
153+
}
154+
}

‎src/com/duwei/encrypt/MessageDigestTest.java

Lines changed: 33 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,33 @@
1+
package com.duwei.encrypt;
2+
3+
import java.security.MessageDigest;
4+
import java.security.NoSuchAlgorithmException;
5+
6+
public class MessageDigestTest {
7+
8+
/**
9+
* @param args
10+
*/
11+
public static void main(String[] args) {
12+
// TODO Auto-generated method stub
13+
14+
}
15+
16+
17+
public void MDAl(String content){
18+
//常用算法：MD5、SHA、CRC
19+
MessageDigest digest = null;
20+
try {
21+
digest = MessageDigest.getInstance("MD5");
22+
} catch (NoSuchAlgorithmException e) {
23+
e.printStackTrace();
24+
}
25+
byte[] result = digest.digest(content.getBytes());
26+
//消息摘要的结果一般都是转换成16 进制字符串形式展示
27+
//String hex = Hex.encode(result);
28+
//MD5 结果为16 字节（128 个比特位）、转换为16 进制表示后长度是32 个字符
29+
//SHA 结果为20 字节（160 个比特位）、转换为16 进制表示后长度是40 个字符
30+
//System.out.println(hex);
31+
}
32+
33+
}

‎src/com/duwei/encrypt/MyEncrypt.java

Lines changed: 60 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,60 @@
1+
package com.duwei.encrypt;
2+
3+
public class MyEncrypt {
4+
public static void main(String[] args) {
5+
6+
}
7+
8+
/**
9+
* 加密
10+
* @param input 数据源（需要加密的数据）
11+
* @param key 秘钥，即偏移量
12+
* @return 返回加密后的数据
13+
*/
14+
public static String encrypt(String input, int key) {
15+
//得到字符串里的每一个字符
16+
char[] array = input.toCharArray();
17+
for (int i = 0; i < array.length; ++i) {
18+
//字符转换成ASCII 码值
19+
int ascii = array[i];
20+
//字符偏移，例如a->b
21+
ascii = ascii + key;
22+
//ASCII 码值转换为char
23+
char newChar = (char) ascii;
24+
//替换原有字符
25+
array[i] = newChar;
26+
27+
//以上4 行代码可以简写为一行
28+
//array[i] = (char) (array[i] + key);
29+
}
30+
//字符数组转换成String
31+
return new String(array);
32+
}
33+
34+
/**
35+
* 解密
36+
* @param input 数据源（被加密后的数据）
37+
* @param key 秘钥，即偏移量
38+
* @return 返回解密后的数据
39+
*/
40+
public static String decrypt(String input, int key) {
41+
//得到字符串里的每一个字符
42+
char[] array = input.toCharArray();
43+
for (int i = 0; i < array.length; ++i) {
44+
//字符转换成ASCII 码值
45+
int ascii = array[i];
46+
//恢复字符偏移，例如b->a
47+
ascii = ascii - key;
48+
//ASCII 码值转换为char
49+
char newChar = (char) ascii;
50+
//替换原有字符
51+
array[i] = newChar;
52+
53+
//以上4 行代码可以简写为一行
54+
//array[i] = (char) (array[i] - key);
55+
}
56+
57+
//字符数组转换成String
58+
return new String(array);
59+
}
60+
}

‎src/com/duwei/encrypt/RSA.java

Lines changed: 51 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,51 @@
1+
package com.duwei.encrypt;
2+
3+
import java.security.InvalidKeyException;
4+
import java.security.KeyPair;
5+
import java.security.KeyPairGenerator;
6+
import java.security.NoSuchAlgorithmException;
7+
import java.security.PrivateKey;
8+
import java.security.PublicKey;
9+
10+
import javax.crypto.BadPaddingException;
11+
import javax.crypto.Cipher;
12+
import javax.crypto.IllegalBlockSizeException;
13+
import javax.crypto.NoSuchPaddingException;
14+
15+
public class RSA {
16+
//一次性加密数据的长度不能大于117 字节
17+
private static final int ENCRYPT_BLOCK_MAX = 117;
18+
//一次性解密的数据长度不能大于128 字节
19+
private static final int DECRYPT_BLOCK_MAX = 128;
20+
21+
public static void main(String[] args) {
22+
23+
}
24+
/**
25+
* RSA加密解密API
26+
* @param content
27+
*/
28+
public void encryptRsa(String content) {
29+
try {
30+
// 1，获取cipher 对象
31+
Cipher cipher = Cipher.getInstance("RSA");
32+
// 2，通过秘钥对生成器KeyPairGenerator 生成公钥和私钥
33+
KeyPair keyPair = KeyPairGenerator
34+
.getInstance("RSA")
35+
.generateKeyPair();
36+
PublicKey publicKey = keyPair.getPublic();//公钥
37+
PrivateKey privateKey = keyPair.getPrivate();//私钥
38+
// 3,使用公钥初始化密码器
39+
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
40+
// 4，执行加密操作
41+
byte[] result = cipher.doFinal(content.getBytes());
42+
// 使用私钥初始化密码器
43+
cipher.init(Cipher.DECRYPT_MODE, privateKey);
44+
// 执行解密操作
45+
byte[] deResult = cipher.doFinal(result);
46+
} catch (Exception e) {
47+
e.printStackTrace();
48+
}
49+
}
50+
51+
}

0 commit comments

Comments
 (0)