JAVA RSA加密解密 工具类

1：RsaUtil.JAVA

import org.Apache.commons.codec.binary.Base64;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
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.HashMap;
import java.util.Map;

public class RsaUtil {
    public static final String KEY_ALGORITHM = "RSA";
    //public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
    private static final String PUBLIC_KEY = "FrankPublic";
    private static final String PRIVATE_KEY = "FrankPrivateKey";
    /**
     * 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;
    //获得公钥
    public static String getPublicKey(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);
        //byte[] publicKey = key.getEncoded();
        //编码返回字符串
        return encryptBASE64(key.getEncoded());
    }

    //获得私钥
    public static String getPrivateKey(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);
        //byte[] privateKey = key.getEncoded();
        //编码返回字符串
        return encryptBASE64(key.getEncoded());
    }

    //解码返回byte
    public static byte[] decryptBASE64(String key) throws Exception {
        return (new BASE64Decoder()).decodeBuffer(key);
    }

    //编码返回字符串
    public static String encryptBASE64(byte[] key) throws Exception {
        return (new BASE64Encoder()).encodeBuffer(key);
    }

    //map对象中存放公私钥
    public static Map<String, Object> initKey() throws Exception {
        //获得对象 KeyPairGenerator 参数 RSA 1024个字节
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        //通过对象 KeyPairGenerator 获取对象KeyPair
        KeyPair keyPair = keyPairGen.generateKeyPair();
        //通过对象 KeyPair 获取RSA公私钥对象RSAPublicKey RSAPrivateKey
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        //公私钥对象存入map中
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }

    /**
     * 获取私钥
     *
     * @param privateKey 私钥字符串
     * @return
     */
    public static PrivateKey getPrivateKey() throws Exception {
        String privateKey="XXX";
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
        return keyFactory.generatePrivate(keySpec);
    }

    /**
     * 获取公钥
     *
     * @param publicKey 公钥字符串
     * @return
     */
    public static PublicKey getPublicKey() throws Exception {
        String publicKey="XXX";
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
        return keyFactory.generatePublic(keySpec);
    }


    /**
     * RSA加密
     *
     * @param data      待加密数据
     * @return
     */
    public static String encrypt(String data) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, getPublicKey());
        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));
    }

    /**
     * RSA解密
     *
     * @param data       待解密数据
     * @return
     */
    public static String decrypt(String data) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, getPrivateKey());
        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");
    }
}

2:调用方式

先调用 initKey() 方法 获取到一个Map对象，里面包含了公钥和私钥，key值就是上面定义的 PUBLIC_KEY 和 PRIVATE_KEY 两个常量

如果想看里面具体的 公钥和私钥字符串形式 将此Map对象做为参数，

传递到 getPublicKey(Map<String, Object> keyMap) 和 getPrivateKey(Map<String, Object> keyMap) 方法中即可获取到值

好了，看完以后，将需要加密的字符放到 encrypt(String data) 方法中进行加密，将需要解密的字符放到  decrypt(String data) 方法中进行解密

即可。