RSA分段加密 - Java
前言
RSA的 key 长度为 1024 用公钥加密比较长的字符串时会异常，这里介绍 java 如何对长文本进行分段加密
- 附上其它链接：
RSA加密 - Java
RSA加密 - Vue
RSA分段解密 - Vue
具体实现
- 实现类
import com.alibaba.fastjson.JSONObject;
import org.apache.commons.lang3.ArrayUtils;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.EncodedKeySpec;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;
public class RSAUtils {
/**
* 公钥
*/
private static final String PUBLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCaaI4MBywkCjIppZnraqN3pbrcZTq/t0+aMBo8K3pK9BDD6XkM6N2Yfcva7BSFbUWuAcI7piXak0UKn9CElDuhNzUSgQn4IXKxIt3Iva5cV83qYumj+0yRjjLT8Muu1Y1rgBZjY9oBwhVoV+Twg25+UJ+6Q6HM4xTwQQJDoyy4jwIDAQAB";
/**
* 私钥
*/
private static final String PRIVATE_KEY = "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";
/**
* 私钥分段加密
* @param content
* @return
* @throws Exception
*/
public static String encryptLongByPrivateKey(String content) throws Exception {
// 获取私钥
PrivateKey privateKey = getPrivateKey(PRIVATE_KEY);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
// URLEncoder编码解决中文乱码问题
byte[] data = URLEncoder.encode(content, "UTF-8").getBytes("UTF-8");
// 加密时超过117字节就报错。为此采用分段加密的办法来加密
byte[] enBytes = null;
for (int i = 0; i < data.length; i += 117) {
// 注意要使用2的倍数，否则会出现加密后的内容再解密时为乱码
byte[] doFinal = cipher.doFinal(ArrayUtils.subarray(data, i, i + 117));
enBytes = ArrayUtils.addAll(enBytes, doFinal);
}
return Base64.getEncoder().encodeToString(enBytes);
}
/**
* 公钥分段解密
* @param content
* @return
* @throws Exception
*/
public static String decryptLongByPublicKey(String content) throws Exception {
//获取公钥
PublicKey publicKey = getPublicKey(PUBLIC_KEY);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, publicKey);
byte[] data = Base64.getDecoder().decode(content);
// 返回UTF-8编码的解密信息
int inputLen = data.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 对数据分段解密
while (inputLen - offSet > 0) {
if (inputLen - offSet > 128) {
cache = cipher.doFinal(data, offSet, 128);
} else {
cache = cipher.doFinal(data, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * 128;
}
byte[] decryptedData = out.toByteArray();
out.close();
return URLDecoder.decode(new String(decryptedData, "UTF-8"));
}
/**
* 将base64编码后的公钥字符串转成PublicKey实例
* @param publicKey 公钥
* @return PublicKey实例
* @throws Exception 异常信息
*/
public static PublicKey getPublicKey(String publicKey) throws Exception {
EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(publicKey));
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return keyFactory.generatePublic(keySpec);
}
/**
* 将base64编码后的私钥字符串转成PrivateKey实例
* @param privateKey 私钥
* @return PrivateKey实例
* @throws Exception 异常信息
*/
private static PrivateKey getPrivateKey(String privateKey) throws Exception {
byte[] keyBytes = Base64.getDecoder().decode(privateKey);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return keyFactory.generatePrivate(keySpec);
}
public static void main(String[] args) throws Exception {
Map<String,Object> map = new HashMap<>();
map.put("name", "Cosini");
map.put("phone", "13888888888");
map.put("explain", "加解密失败或中文乱码请仔细查看demo");
String content = JSONObject.toJSONString(map);
// 密文
String cipherText = RSAUtils.encryptLongByPrivateKey(content);
System.out.println("encryptLongByPrivateKey: " + cipherText);
// 明文
String plainText = RSAUtils.decryptLongByPublicKey(cipherText);
System.out.println("decryptLongByPublicKey: " + plainText);
}
}
- 结果如下所示：
- 注：分段加密中文乱码是因为一个中文3个字节，在解密最大长度分界如果被分隔成了两段转成 String 就会产生乱码。这里使用 URLEncoder 进行编码，解决中文字符乱码问题。
源码
