Java RSA加密

文章目录

1. 1. 生成一对密匙，支持数据分段加解密

生成一对密匙，支持数据分段加解密

• 加密需要使用的编码

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
import java.security.MessageDigest;

public class Coder {

    public static final String KEY_SHA="SHA";
    public static final String KEY_MD5="MD5";

    /**
     * BASE64解密
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptBASE64(String key) throws Exception{
        return (new BASE64Decoder()).decodeBuffer(key);
    }

    /**
     * BASE64加密
     * @param key
     * @return
     * @throws Exception
     */
    public static String encryptBASE64(byte[] key)throws Exception{
        return (new BASE64Encoder()).encodeBuffer(key);
    }

    /**
     * MD5加密
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptMD5(byte[] data)throws Exception{
        MessageDigest md5 = MessageDigest.getInstance(KEY_MD5);
        md5.update(data);
        return md5.digest();
    }

    /**
     * SHA加密
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptSHA(byte[] data)throws Exception{
        MessageDigest sha = MessageDigest.getInstance(KEY_SHA);
        sha.update(data);
        return sha.digest();
    }
}

• RSA生成密匙对 和加解密

import com.campus.util.string.StringUtil;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
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;

public class RSAKey extends Coder{

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

    //签名算法
    private static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    //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)
     * @return Map<String, Object>
     * @throws Exception
     */
    private 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;
    }

    /**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     *
     * @param data 已加密数据
     * @param privateKey 私钥(BASE64编码)
     *
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = decryptBASE64(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 encryptBASE64(signature.sign());
    }

    /**
     * <p>
     * 校验数字签名
     * </p>
     *
     * @param data 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign 数字签名
     *
     * @return
     * @throws Exception
     *
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        byte[] keyBytes = decryptBASE64(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(decryptBASE64(sign));
    }

    /**
     * <P>
     * 私钥解密
     * </p>
     *
     * @param encryptedData 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    private static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
            throws Exception {
        byte[] keyBytes = decryptBASE64(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);
        return segmentData(encryptedData,cipher,MAX_DECRYPT_BLOCK);
    }

    /**
     * <p>
     * 公钥解密
     * </p>
     *
     * @param encryptedData 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
            throws Exception {
        byte[] keyBytes = decryptBASE64(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);
        return segmentData(encryptedData,cipher,MAX_DECRYPT_BLOCK);
    }

    /**
     * 对数据分段加密
     * @param data  byte[]
     * @param cipher Cipher
     * @return byte[]
     * @throws Exception
     */
    private static byte[] segmentData(byte[] data,Cipher cipher,int max) throws Exception{
        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) {
                cache = cipher.doFinal(data, offSet, max);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * max;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }



    /**
     * <p>
     * 公钥加密
     * </p>
     *
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    private static byte[] encryptByPublicKey(byte[] data, String publicKey)
            throws Exception {
        byte[] keyBytes = decryptBASE64(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);
        return segmentData(data,cipher,MAX_ENCRYPT_BLOCK);
    }



    /**
     * <p>
     * 私钥加密
     * </p>
     *
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    private static byte[] encryptByPrivateKey(byte[] data, String privateKey)
            throws Exception {
        byte[] keyBytes = decryptBASE64(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);
        return segmentData(data,cipher,MAX_ENCRYPT_BLOCK);
    }



    /**
     * <p>
     * 获取私钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    private static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return encryptBASE64(key.getEncoded());
    }


    /**
     * <p>
     * 获取公钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    private static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return encryptBASE64(key.getEncoded());
    }


    /**
     * 获取一对RSA 密匙
     * @return Map<String, String>
     */
    public static Map<String, String> getKeys(){
        Map<String, String> map;
        try {
            Map<String, Object> maps = genKeyPair();
            map = new HashMap<>();
            String publicKey = getPublicKey(maps);
            String privateKey = getPrivateKey(maps);

            map.put("ServicePub",publicKey);
            map.put("ServicePri",privateKey);
            return map;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return  null;
    }


    /**
     * 传入密钥 和数据 进行解密
     * @param priKey String
     * @param value String
     * @return String
     */
    public static String RSADecodeRes(String priKey, String value){
        if (StringUtil.isEmpty(priKey) || StringUtil.isEmpty(value)){
            return null;
        }

        try {
            byte[] value_byte = decryptByPrivateKey(decryptBASE64(value),priKey);
            return new String(value_byte);
        } catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }



    /**
     * 根据公匙 进行加密
     * @param pubKey
     * @param value
     * @return String
     */
    public static String RSAEncodeRes(String pubKey, String value) throws Exception {

        if (StringUtil.isEmpty(pubKey) || StringUtil.isEmpty(value)){
            return null;
        }

        byte[] val_byte = encryptByPublicKey(value.getBytes(),pubKey);
        return encryptBASE64(val_byte);
    }




/**
    public static void main(String[] args) throws Exception {
        Map<String, Object> map = genKeyPair();
        String pub = getPublicKey(map);
        String pri = getPrivateKey(map);

        JSONObject json = new JSONObject();
        json.put("pub",pub);
        json.put("pir",pri);

    }
*/

}