MD5,Base64,RSAUtils 加密

最新推荐文章于 2025-06-05 18:06:13 发布

lvdaan

最新推荐文章于 2025-06-05 18:06:13 发布

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CC 4.0 BY-SA版权

分类专栏： java Util 文章标签： MD5 Base64 RSA

本文链接：https://blog.youkuaiyun.com/lvdaan/article/details/79226095

java Util 专栏收录该内容

10 篇文章

订阅专栏

本文介绍了几种常用的加密解密技术，包括MD5、Base64和RSA等算法的应用实例。详细解析了各种加密方式的实现原理及代码实现，并提供了一个完整的RSA加密解密示例。

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俗话说的好前人种树后人乘凉，最近用到加密解密相关，根据前辈们的文章做个记录，方便以后直接使用

MD5加密

package com.qingxu.extension.util;

import java.security.MessageDigest;

/**
 * 编码工具类
 * Created by Administrator on 2018/1/25.
 */
public class MD5Util {

    /**
     *  MD5加密
     */
    public static String MD5(String key) {
        char hexDigits[] = {
                '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
        };
        try {
            byte[] btInput = key.getBytes();
            // 获得MD5摘要算法的 MessageDigest 对象
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            // 使用指定的字节更新摘要
            mdInst.update(btInput);
            // 获得密文
            byte[] md = mdInst.digest();
            // 把密文转换成十六进制的字符串形式
            int j = md.length;
            char str[] = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(str);
        } catch (Exception e) {
            return null;
        }
    }


}

其中hexDigits[] 中的字符大小写可以根据自己需要调换

二、Base64 加密解密，因为java新增的很好实现

package com.qingxu.extension.util;

import com.sun.org.apache.xml.internal.security.utils.Base64;

import java.io.*;


/**
 * BASE64编码解码工具包
 * 依赖javabase64-1.3.1.jar
 */
public class Base64Utils {

    /**
     * 文件读取缓冲区大小
     */
    private static final int CACHE_SIZE = 1024;

    /**
     * BASE64字符串解码为二进制数据
     * @param base64
     * @return
     * @throws Exception
     */
    public static byte[] decode(String base64) throws Exception {
        return Base64.decode(base64.getBytes());
    }

    /**
     * 二进制数据编码为BASE64字符串
     * @param bytes
     * @return
     * @throws Exception
     */
    public static String encode(byte[] bytes) throws Exception {
        return new String(Base64.encode(bytes));
    }

    /**
     * 将文件编码为BASE64字符串
     * 大文件慎用，可能会导致内存溢出
     * @param filePath
     *            文件绝对路径
     * @return
     * @throws Exception
     */
    public static String encodeFile(String filePath) throws Exception {
        byte[] bytes = fileToByte(filePath);
        return encode(bytes);
    }

    /**
     * BASE64字符串转回文件
     * @param filePath
     *            文件绝对路径
     * @param base64
     *            编码字符串
     * @throws Exception
     */
    public static void decodeToFile(String filePath, String base64) throws Exception {
        byte[] bytes = decode(base64);
        byteArrayToFile(bytes, filePath);
    }

    /**
     * 文件转换为二进制数组
     * @param filePath
     *            文件路径
     * @return
     * @throws Exception
     */
    public static byte[] fileToByte(String filePath) throws Exception {
        byte[] data = new byte[0];
        File file = new File(filePath);
        if (file.exists()) {
            FileInputStream in = new FileInputStream(file);
            ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
            byte[] cache = new byte[CACHE_SIZE];
            int nRead = 0;
            while ((nRead = in.read(cache)) != -1) {
                out.write(cache, 0, nRead);
                out.flush();
            }
            out.close();
            in.close();
            data = out.toByteArray();
        }
        return data;
    }

    /**
     * 二进制数据写文件
     * @param bytes
     *            二进制数据
     * @param filePath
     *            文件生成目录
     */
    public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {
        InputStream in = new ByteArrayInputStream(bytes);
        File destFile = new File(filePath);
        if (!destFile.getParentFile().exists()) {
            destFile.getParentFile().mkdirs();
        }
        destFile.createNewFile();
        OutputStream out = new FileOutputStream(destFile);
        byte[] cache = new byte[CACHE_SIZE];
        int nRead = 0;
        while ((nRead = in.read(cache)) != -1) {
            out.write(cache, 0, nRead);
            out.flush();
        }
        out.close();
        in.close();
    }

}

三、RSA加密

package com.qingxu.extension.encode;

import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

/**
 * RSA公钥/私钥/签名工具包
 * 罗纳德·李维斯特（Ron [R]ivest）、阿迪·萨莫尔（Adi [S]hamir）和伦纳德·阿德曼（Leonard [A]dleman）
 * 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式<br/>
 * 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密，<br/>
 * 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全
 *

 */
public class RSAUtils {

    /**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";

    /**
     * 签名算法MD5withRSA
     */
    public static final String SIGNATURE_ALGORITHM = "SHA1withRSA";

    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";

    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    /**
     * 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;

    /**
     * 生成密钥对(公钥和私钥)
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        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;
    }

    /**
     * 用私钥对信息生成数字签名
     * @param data 已加密数据
     * @param privateKey 私钥(BASE64编码)
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);

        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);

        return Base64Utils.encode(signature.sign());
    }

    /**
     * 校验数字签名
     * @param data 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign 数字签名
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(Base64Utils.decode(sign));
    }

    /**
     * 私钥解密
     * @param encryptedData 已加密数据
     * @param privateKey 私钥(BASE64编码)
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.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(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;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * 公钥解密
     * @param encryptedData 已加密数据
     * @param publicKey 公钥(BASE64编码)
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.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(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;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * 公钥加密
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     */
    public static byte[] encryptByPublicKey(byte[] data, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.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, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * 私钥加密
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     */
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.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, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * 获取私钥
     * @param keyMap 密钥对
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64Utils.encode(key.getEncoded());
    }

    /**
     * 获取公钥
     * @param keyMap 密钥对
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64Utils.encode(key.getEncoded());
    }

}

其中的签名算法可以根据自己需求做改动，在底层源码中有记载

四、示例

package com.qingxu.extension.encode;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.security.KeyFactory;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

public class Rsa {

    private String priKey;
    private String pubKey;

    public static void main(String[] args) {
        Rsa rsa = new Rsa();
        String str = "我要加密这段文字。";
        System.out.println("原文:"+"我要加密这段文字。");
        String crypt = rsa.encryptByPrivateKey(str);
        System.out.println("私钥加密密文:"+crypt);
        String result = rsa.decryptByPublicKey(crypt);
        System.out.println("原文:"+result);

        System.out.println("---");

        str = "我要加密这段文字。";
        System.out.println("原文:"+"我要加密这段文字。");
        crypt = rsa.encryptByPublicKey(str);
        System.out.println("公钥加密密文:"+crypt);
        result = rsa.decryptByPrivateKey(crypt);
        System.out.println("原文:"+result);

        System.out.println("---");

        str = "我要签名这段文字。";
        System.out.println("原文："+str);
        String str1 = rsa.signByPrivateKey(str);
        System.out.println("签名结果："+str1);
        if(rsa.verifyByPublicKey(str1, str)){
            System.out.println("成功");
        } else {
            System.out.println("失败");
        }
    }

    public Rsa(){
        priKey = readStringFromFile("java_private.pem");
        pubKey = readStringFromFile("java_public.pem");
    }

    /**
     * 使用私钥加密
     * @see decByPriKey
     */
    public String encryptByPrivateKey(String data) {
        // 加密
        String str = "";
        try {
            byte[] pribyte = base64decode(priKey.trim());
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pribyte);
            KeyFactory fac = KeyFactory.getInstance("RSA");
            RSAPrivateKey privateKey = (RSAPrivateKey) fac.generatePrivate(keySpec);
            Cipher c1 = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            c1.init(Cipher.ENCRYPT_MODE, privateKey);
            str = base64encode(c1.doFinal(data.getBytes()));
        } catch (Exception e) {
            e.printStackTrace();

        }
        return str;
    }

    /**
     * 使用私钥解密
     * @see decByPriKey
     */
    public String decryptByPrivateKey(String data) {
        // 加密
        String str = "";
        try {
            byte[] pribyte = base64decode(priKey.trim());
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pribyte);
            KeyFactory fac = KeyFactory.getInstance("RSA");
            RSAPrivateKey privateKey = (RSAPrivateKey) fac.generatePrivate(keySpec);
            Cipher c1 = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            c1.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] temp = c1.doFinal(base64decode(data));
            str = new String(temp);
        } catch (Exception e) {
            e.printStackTrace();

        }
        return str;
    }


    /**
     * 使用公钥加密
     * @see decByPriKey
     */
    public String encryptByPublicKey(String data) {
        // 加密
        String str = "";
        try {
            byte[] pubbyte = base64decode(pubKey.trim());
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(pubbyte);
            KeyFactory fac = KeyFactory.getInstance("RSA");
            RSAPublicKey rsaPubKey = (RSAPublicKey) fac.generatePublic(keySpec);
            Cipher c1 = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            c1.init(Cipher.ENCRYPT_MODE, rsaPubKey);
            str = base64encode(c1.doFinal(data.getBytes()));
        } catch (Exception e) {
            e.printStackTrace();

        }
        return str;
    }

    /**
     * 使用公钥解密
     * @see decByPriKey
     */
    public String decryptByPublicKey(String data) {
        // 加密
        String str = "";
        try {
            byte[] pubbyte = base64decode(pubKey.trim());
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(pubbyte);
            KeyFactory fac = KeyFactory.getInstance("RSA");
            RSAPublicKey rsaPubKey = (RSAPublicKey) fac.generatePublic(keySpec);
            Cipher c1 = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            c1.init(Cipher.DECRYPT_MODE, rsaPubKey);
            byte[] temp = c1.doFinal(base64decode(data));
            str = new String(temp);
        } catch (Exception e) {
            e.printStackTrace();

        }
        return str;
    }
    /**
     * 本方法使用SHA1withRSA签名算法产生签名
     * @param String src 签名的原字符串
     * @return String 签名的返回结果(16进制编码)。当产生签名出错的时候，返回null。
     */
    public String signByPrivateKey(String src) {
        try {
            Signature sigEng = Signature.getInstance("SHA1withRSA");
            byte[] pribyte = base64decode(priKey.trim());
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pribyte);
            KeyFactory fac = KeyFactory.getInstance("RSA");
            RSAPrivateKey privateKey = (RSAPrivateKey) fac.generatePrivate(keySpec);
            sigEng.initSign(privateKey);
            sigEng.update(src.getBytes());
            byte[] signature = sigEng.sign();
            return base64encode(signature);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 使用共钥验证签名
     * @param sign
     * @param src
     * @return
     */
    public boolean verifyByPublicKey(String sign, String src) {
        try {
            Signature sigEng = Signature.getInstance("SHA1withRSA");
            byte[] pubbyte = base64decode(pubKey.trim());
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(pubbyte);
            KeyFactory fac = KeyFactory.getInstance("RSA");
            RSAPublicKey rsaPubKey = (RSAPublicKey) fac.generatePublic(keySpec);
            sigEng.initVerify(rsaPubKey);
            sigEng.update(src.getBytes());
            byte[] sign1 = base64decode(sign);
            return sigEng.verify(sign1);
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     *  base64加密
     * @param bstr
     * @return
     */
    @SuppressWarnings("restriction")
    private String base64encode(byte[] bstr) {
        String str =  new sun.misc.BASE64Encoder().encode(bstr);
        str = str.replaceAll("\r\n", "").replaceAll("\r", "").replaceAll("\n", "");
        return str;
    }

    /**
     * base64解密
     * @param str
     * @return byte[]
     */
    @SuppressWarnings("restriction")
    private byte[] base64decode(String str) {
        byte[] bt = null;
        try {
            sun.misc.BASE64Decoder decoder = new sun.misc.BASE64Decoder();
            bt = decoder.decodeBuffer(str);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return bt;
    }

    /**
     * 从文件中读取所有字符串
     * @param fileName
     * @return	String
     */
    private String readStringFromFile(String fileName){
        StringBuffer str = new StringBuffer();
        try {
            File file = new File(fileName);
            FileReader fr = new FileReader(file);
            char[] temp = new char[1024];
            while (fr.read(temp) != -1) {
                str.append(temp);
            }
            fr.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

        }
        return str.toString();
    }
}