java8中怎么实现Rsa加解密和签名验签
java8中怎么实现Rsa加解密和签名验签，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
直接上码
package util;
import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;
import javax.crypto.Cipher;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
public class RsaUtil {
/**
* RSA算法
*/
public static final String KEY_ALGORITHM_RSA = "RSA";
/**
* Map获取公钥的键
*/
private static final String PUBLIC_KEY = "RSAPublicKey";
/**
* Map获取私钥的键
*/
private static final String PRIVATE_KEY = "RSAPrivateKey";
/**
* 签名算法: MD5withRSA
*/
public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
/**
* 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 = 256;
//获得公钥字符串
public static String getPublicKeyStr(Map<String, Object> keyMap) throws Exception {
//获得map中的公钥对象 转为key对象
Key key = (Key) keyMap.get(PUBLIC_KEY);
//编码返回字符串
return encryptBASE64(key.getEncoded());
}
//获得私钥字符串
public static String getPrivateKeyStr(Map<String, Object> keyMap) throws Exception {
//获得map中的私钥对象 转为key对象
Key key = (Key) keyMap.get(PRIVATE_KEY);
//编码返回字符串
return encryptBASE64(key.getEncoded());
}
/**
* 获取公钥
* @param key base64编码后公钥
* @return
* @throws Exception
*/
public static PublicKey getPublicKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = (new BASE64Decoder()).decodeBuffer(key);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM_RSA);
return keyFactory.generatePublic(keySpec);
}
/**
* 获取私钥
*
* @param key base64编码后私钥
* @return
* @throws Exception
*/
public static PrivateKey getPrivateKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = (new BASE64Decoder()).decodeBuffer(key);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM_RSA);
return keyFactory.generatePrivate(keySpec);
}
// base64解码返回byte
public static byte[] decryptBASE64(String key) throws Exception {
return (new BASE64Decoder()).decodeBuffer(key);
}
// base64编码返回字符串
public static String encryptBASE64(byte[] key) throws Exception {
return (new BASE64Encoder()).encodeBuffer(key);
}
// 签名
public static byte[] sign(byte[] data, String privateKeyStr) throws Exception {
PrivateKey priK = getPrivateKey(privateKeyStr);
Signature sig = Signature.getInstance(SIGNATURE_ALGORITHM);
sig.initSign(priK);
sig.update(data);
return sig.sign();
}
// 验证签名
public static boolean verify(byte[] data, byte[] sign, String publicKeyStr) throws Exception {
PublicKey pubK = getPublicKey(publicKeyStr);
Signature sig = Signature.getInstance(SIGNATURE_ALGORITHM);
sig.initVerify(pubK);
sig.update(data);
return sig.verify(sign);
}
// 初始化公钥私钥
public static Map<String, Object> initKey() throws Exception {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM_RSA);
// 初始化密钥对生成器，密钥大小为96-1024位
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
Map<String, Object> keyMap = new HashMap<String, Object>(2);
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}
// 加密
public static byte[] encrypt(byte[] plainText, String publicKeyStr) throws Exception {
PublicKey publicKey = getPublicKey(publicKeyStr);
Cipher cipher = Cipher.getInstance(KEY_ALGORITHM_RSA);
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
int inputLen = plainText.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
int i = 0;
byte[] cache;
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
cache = cipher.doFinal(plainText, offSet, MAX_ENCRYPT_BLOCK);
} else {
cache = cipher.doFinal(plainText, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_ENCRYPT_BLOCK;
}
byte[] encryptText = out.toByteArray();
out.close();
return encryptText;
}
// 解密
public static byte[] decrypt(byte[] encryptText, String privateKeyStr) throws Exception {
PrivateKey privateKey = getPrivateKey(privateKeyStr);
Cipher cipher = Cipher.getInstance(KEY_ALGORITHM_RSA);
cipher.init(Cipher.DECRYPT_MODE, privateKey);
int inputLen = encryptText.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(encryptText, offSet, MAX_DECRYPT_BLOCK);
} else {
cache = cipher.doFinal(encryptText, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_DECRYPT_BLOCK;
}
byte[] plainText = out.toByteArray();
out.close();
return plainText;
}
public static void main(String[] args) {
Map<String, Object> keyMap;
byte[] cipherText;
String input = "Hello World! 您好 世界！！";
try {
keyMap = initKey();
String publicKey = getPublicKeyStr(keyMap);
System.out.println("公钥------------------");
System.out.println(publicKey);
String privateKey = getPrivateKeyStr(keyMap);
System.out.println("私钥------------------");
System.out.println(privateKey);
System.out.println("测试可行性-------------------");
System.out.println("明文=======" + input);
cipherText = encrypt(input.getBytes(), publicKey);
//加密后的东西
System.out.println("密文=======" + new String(cipherText));
//开始解密
byte[] plainText = decrypt(cipherText, privateKey);
System.out.println("解密后明文===== " + new String(plainText));
System.out.println("验证签名-----------");
String str = "被签名的内容";
System.out.println("\n原文:" + str);
byte[] signature = sign(str.getBytes(), privateKey);
boolean status = verify(str.getBytes(), signature, publicKey);
System.out.println("验证情况：" + status);
} catch (Exception e) {
e.printStackTrace();
}
}
}
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