1.代码
package com.peak.common.utils;
import org.apache.tomcat.util.codec.binary.Base64;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
/**
* @ClassName RSAUtils
* @Description: RSA 加密解密工具类
* @Author jql
* @Date 2020/7/17 13:29
* @Version V1.0
**/
public class RSAUtils {
/**
* RSA最大加密明文大小
**/
private static final int MAX_ENCRYPT_BLOCK = 117;
/**
* RSA最大解密密文大小
**/
private static final int MAX_DECRYPT_BLOCK = 128;
public static final String KEY_ALGORITHM = "RSA";
public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
/**
* @Title: getKeyPair
* @Description: 获取密钥对
* @Date: 2020/7/17 14:44
* @return: java.security.KeyPair
**/
public static KeyPair getKeyPair() throws Exception {
KeyPairGenerator generator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
generator.initialize(1024);
return generator.generateKeyPair();
}
/**
* @Title: getPrivateKey
* @Description: 获取私钥
* @param privateKey 私钥字符串
* @Date: 2020/7/17 14:45
* @return: java.security.PrivateKey
**/
public static PrivateKey getPrivateKey(String privateKey) throws Exception {
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
return keyFactory.generatePrivate(keySpec);
}
/**
* @Title: getPublicKey
* @Description: 获取公钥
* @param publicKey 公钥字符串
* @Date: 2020/7/17 14:47
* @return: java.security.PublicKey
**/
public static PublicKey getPublicKey(String publicKey) throws Exception {
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
return keyFactory.generatePublic(keySpec);
}
/**
* @Title: encrypt
* @Description: RSA 加密
* @param data 待加密数据
* @param publicKey 公钥
* @Date: 2020/7/17 14:47
* @return: java.lang.String
**/
public static String encrypt(String data, PublicKey publicKey) throws Exception {
Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
int inputLen = data.getBytes().length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offset = 0;
byte[] cache;
int i = 0;
// 对数据分段加密
while (inputLen - offset > 0) {
if (inputLen - offset > MAX_ENCRYPT_BLOCK) {
cache = cipher.doFinal(data.getBytes(), offset, MAX_ENCRYPT_BLOCK);
} else {
cache = cipher.doFinal(data.getBytes(), offset, inputLen - offset);
}
out.write(cache, 0, cache.length);
i++;
offset = i * MAX_ENCRYPT_BLOCK;
}
byte[] encryptedData = out.toByteArray();
out.close();
// 获取加密内容使用base64进行编码,并以UTF-8为标准转化成字符串
// 加密后的字符串
return new String(Base64.encodeBase64String(encryptedData));
}
/**
* @Title: decrypt
* @Description: RSA 解密
* @param data 待解密数据
* @param privateKey 私钥
* @Date: 2020/7/17 14:48
* @return: java.lang.String
**/
public static String decrypt(String data, PrivateKey privateKey) throws Exception {
Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, privateKey);
byte[] dataBytes = Base64.decodeBase64(data);
int inputLen = dataBytes.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 > MAX_DECRYPT_BLOCK) {
cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
} else {
cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
}
out.write(cache, 0, cache.length);
i++;
offset = i * MAX_DECRYPT_BLOCK;
}
byte[] decryptedData = out.toByteArray();
out.close();
// 解密后的内容
return new String(decryptedData, "UTF-8");
}
/**
* @Title: sign
* @Description: 签名
* @param data 待签名数据
* @param privateKey 私钥
* @Date: 2020/7/17 14:49
* @return: java.lang.String
**/
public static String sign(String data, PrivateKey privateKey) throws Exception {
byte[] keyBytes = privateKey.getEncoded();
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PrivateKey key = keyFactory.generatePrivate(keySpec);
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initSign(key);
signature.update(data.getBytes());
return new String(Base64.encodeBase64(signature.sign()));
}
/**
* @Title: verify
* @Description: 验签
* @param srcData 原始字符串
* @param publicKey 公钥
* @param sign 签名
* @Date: 2020/7/17 14:50
* @return: boolean
**/
public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {
byte[] keyBytes = publicKey.getEncoded();
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PublicKey key = keyFactory.generatePublic(keySpec);
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initVerify(key);
signature.update(srcData.getBytes());
return signature.verify(Base64.decodeBase64(sign.getBytes()));
}
}
2.测试
public static void main(String[] args) {
try {
// 生成密钥对
KeyPair keyPair = getKeyPair();
String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
System.out.println("私钥:" + privateKey);
System.out.println("公钥:" + publicKey);
// RSA加密
String data = "待加密的文字内容";
String encryptData = encrypt(data, getPublicKey(publicKey));
System.out.println("加密后内容:" + encryptData);
// RSA解密
String decryptData = decrypt(encryptData, getPrivateKey(privateKey));
System.out.println("解密后内容:" + decryptData);
// RSA签名
String sign = sign(data, getPrivateKey(privateKey));
// RSA验签
boolean result = verify(data, getPublicKey(publicKey), sign);
System.out.print("验签结果:" + result);
} catch (Exception e) {
e.printStackTrace();
System.out.print("加解密异常");
}
}
参考：https://blog.csdn.net/qy20115549/article/details/83105736