總體思路：前端用公鑰加密，後端用私鑰解密
rsa.html
展示了js進行加密、解密的過程
RSAUtil.java
是一個java類，後端用到的RSA加解密工具類，裏面包含了一個main方法，可以允許進行測試
一般範式
1、前端請求後端生成RSA公鑰信息；
2、後臺端可以利用RSAUtil.java生成的RSA信息，將私鑰自己存起來，將公鑰返回給前端
3、前端拿到公鑰，進行加密，並提交加密後的密文給後端
4、後端拿到前端提交過來的密文，利用之前生成好的私鑰進行解密
rsa.html
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<meta name=viewport content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no">
<meta http-equiv="Cache-Control" content="no-transform"/>
<meta http-equiv="Cache-Control" content="no-siteapp"/>
<meta name="applicable-device" content="pc,mobile">
<script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/jsbn.js"></script>
<script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/jsbn2.js"></script>
<script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/prng4.js"></script>
<script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/rng.js"></script>
<script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/rsa.js"></script>
<script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/rsa2.js"></script>
<title>RSA</title>
</head>
<body>
<script type="text/javascript">
// 這個是後臺生成並返回的RSA信息（公鑰）
var RSADo = {"modulus":"a5261939975948bb7a58dffe5ff54e65f0498f9175f5a09288810b8975871e99af3b5dd94057b0fc07535f5f97444504fa35169d461d0d30cf0192e307727c065168c788771c561a9400fb49175e9e6aa4e23fe11af69e9412dd23b0cb6684c4c2429bce139e848ab26d0829073351f4acd36074eafd036a5eb83359d2a698d3",
"publicExponent":"10001"}
var privateKey = "8e9912f6d3645894e8d38cb58c0db81ff516cf4c7e5a14c7f1eddb1459d2cded4d8d293fc97aee6aefb861859c8b6a3d1dfe710463e1f9ddc72048c09751971c4a580aa51eb523357a3cc48d31cfad1d4a165066ed92d4748fb6571211da5cb14bc11b6e2df7c1a559e6d5ac1cd5c94703a22891464fba23d0d965086277a161"
// 加密：要測試的明文數據
var str = 'test就撒3242旦立刻反擊啊是！@#￥#%……￥#%43'
// 實例化js的RSA對象生成
var rsa = new RSAKey()
rsa.setPublic(RSADo.modulus, RSADo.publicExponent)
var encryptStr = rsa.encrypt(str);
console.log('RSADo', JSON.stringify(RSADo))
console.log('明文（explain）：', str)
console.log('加密後（encrypt）：', encryptStr)
// 解密
rsa.setPrivate(RSADo.modulus, RSADo.publicExponent, privateKey)
var decryptStr = rsa.decrypt(encryptStr)
console.log('解密私鑰：', privateKey)
console.log('解密後（decrypt）', decryptStr)
</script>
</body>
</html>
RSAUtil.java
package com.xxx.common.crypto;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
public class RSAUtil {
private static final int MAX_ENCRYPT_BLOCK = 117; // RSA最大加密明文大小
private static final int MAX_DECRYPT_BLOCK = 128; // RSA最大解密密文大小
/**
* 生成公鑰和私鑰
*
* @throws NoSuchAlgorithmException
*/
public static KeyPair genRSAKeyPair() throws NoSuchAlgorithmException {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(1024);
return keyPairGen.generateKeyPair();
}
/**
* 使用模和指數生成RSA公鑰
* 注意：【此代碼用了默認補位方式，爲RSA/None/PKCS1Padding，不同JDK默認的補位方式可能不同，如Android默認是RSA
* /None/NoPadding】
*
* @param modulus 模
* @param exponent 指數
* @return
*/
public static RSAPublicKey getPublicKey(String modulus, String exponent) {
try {
BigInteger b1 = new BigInteger(modulus, 16);
BigInteger b2 = new BigInteger(exponent, 16);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* 使用模和指數生成RSA私鑰
* 注意：【此代碼用了默認補位方式，爲RSA/None/PKCS1Padding，不同JDK默認的補位方式可能不同，如Android默認是RSA
* /None/NoPadding】
*
* @param modulus 模
* @param exponent 指數
* @return
*/
public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {
try {
BigInteger b1 = new BigInteger(modulus, 16);
BigInteger b2 = new BigInteger(exponent, 16);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* 公鑰加密
*/
public static byte[] encryptByPublicKey(byte[] data, RSAPublicKey publicKey) throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
int inputLen = data.length;
try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
int offSet = 0;
byte[] cache;
int i = 0;
// 對數據分段加密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
} else {
cache = cipher.doFinal(data, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_ENCRYPT_BLOCK;
}
return out.toByteArray();
}
}
/**
* 私鑰解密
*/
public static byte[] decryptByPrivateKey(byte[] encryptedData, RSAPrivateKey privateKey) throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
int inputLen = encryptedData.length;
try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
int offSet = 0;
byte[] cache;
int i = 0;
// 對數據分段解密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
} else {
cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_DECRYPT_BLOCK;
}
return out.toByteArray();
}
}
/**
* ASCII碼轉BCD碼
*/
public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
byte[] bcd = new byte[asc_len / 2];
int j = 0;
for (int i = 0; i < (asc_len + 1) / 2; i++) {
bcd[i] = asc_to_bcd(ascii[j++]);
bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
}
return bcd;
}
public static byte asc_to_bcd(byte asc) {
byte bcd;
if ((asc >= '0') && (asc <= '9'))
bcd = (byte) (asc - '0');
else if ((asc >= 'A') && (asc <= 'F'))
bcd = (byte) (asc - 'A' + 10);
else if ((asc >= 'a') && (asc <= 'f'))
bcd = (byte) (asc - 'a' + 10);
else
bcd = (byte) (asc - 48);
return bcd;
}
/**
* BCD轉字符串
*/
public static String bcd2Str(byte[] bytes) {
char temp[] = new char[bytes.length * 2], val;
for (int i = 0; i < bytes.length; i++) {
val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
val = (char) (bytes[i] & 0x0f);
temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
}
return new String(temp);
}
/**
* 拆分字符串
*/
public static String[] splitString(String string, int len) {
int x = string.length() / len;
int y = string.length() % len;
int z = 0;
if (y != 0) {
z = 1;
}
String[] strings = new String[x + z];
String str = "";
for (int i = 0; i < x + z; i++) {
if (i == x + z - 1 && y != 0) {
str = string.substring(i * len, i * len + y);
} else {
str = string.substring(i * len, i * len + len);
}
strings[i] = str;
}
return strings;
}
/**
* 拆分數組
*/
public static byte[][] splitArray(byte[] data, int len) {
int x = data.length / len;
int y = data.length % len;
int z = 0;
if (y != 0) {
z = 1;
}
byte[][] arrays = new byte[x + z][];
byte[] arr;
for (int i = 0; i < x + z; i++) {
arr = new byte[len];
if (i == x + z - 1 && y != 0) {
System.arraycopy(data, i * len, arr, 0, y);
} else {
System.arraycopy(data, i * len, arr, 0, len);
}
arrays[i] = arr;
}
return arrays;
}
public static void main(String[] args) throws Exception {
KeyPair keyPair = genRSAKeyPair();
//生成公鑰和私鑰
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
//模hex
String modulus = publicKey.getModulus().toString(16);
//公鑰指數hex
String public_exponent = publicKey.getPublicExponent().toString(16);
//私鑰指數hex
String private_exponent = privateKey.getPrivateExponent().toString(16);
System.err.println("public_modulus: " + modulus);
System.err.println("public_exponent: " + public_exponent);
System.err.println("private_exponent: " + private_exponent);
//明文
String plaintStr = "test就撒3242旦立刻反擊啊是！@#￥#%……￥#%43";
System.err.println("plaintStr: " + plaintStr);
//使用模和指數生成公鑰和私鑰
RSAPublicKey pubKey = getPublicKey(modulus, public_exponent);
RSAPrivateKey priKey = getPrivateKey(modulus, private_exponent);
//公鑰加密後的密文
byte[] encryptStr = encryptByPublicKey(plaintStr.getBytes("utf-8"), pubKey);
System.err.println("encryptStr: " + HexUtil.bytesToHexString(encryptStr));
//私鑰解密後的明文
byte[] decryptStr = decryptByPrivateKey(encryptStr, priKey);
System.err.println("decryptStr: " + new String(decryptStr, "utf-8"));
}
}