import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

/**
 * 2022/3/29
 *
 */

public class TestRSA {

    public static String publicKey = "xxxxxx";
    public static String privateKey = "xxxxxx";

    private static String algorithm = "RSA"; //$NON-NLS-1$
    private static final int MAX_ENCRYPT_BLOCK = 117;
    private static final int MAX_DECRYPT_BLOCK = 128;
    private static String data = "123456"; //$NON-NLS-1$

    public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException, InvalidKeyException, IOException {
        String test = testEncrypt(privateKey,data);
        String testDecrypt = testDecrypt(publicKey, test);
        System.out.println(testDecrypt);

    }


    /**
     * 加密
     * @param key
     * @param data
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     * @throws NoSuchPaddingException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     * @throws InvalidKeyException
     * @throws IOException
     */
    public static String testEncrypt(String key,String data) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException, InvalidKeyException, IOException{
        byte[] decode = Base64.getDecoder().decode(key);
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(decode);
        KeyFactory kf = KeyFactory.getInstance(algorithm);
        PrivateKey generatePrivate = kf.generatePrivate(pkcs8EncodedKeySpec);
        Cipher ci = Cipher.getInstance(algorithm);
        ci.init(Cipher.ENCRYPT_MODE, generatePrivate);

        byte[] bytes = data.getBytes();
        int inputLen = bytes.length;
        int offLen = 0;//偏移量
        int i = 0;
        ByteArrayOutputStream bops = new ByteArrayOutputStream();
        while(inputLen - offLen > 0){
            byte [] cache;
            if(inputLen - offLen > 117){
                cache = ci.doFinal(bytes, offLen,117);
            }else{
                cache = ci.doFinal(bytes, offLen,inputLen - offLen);
            }
            bops.write(cache);
            i++;
            offLen = 117 * i;
        }
        bops.close();
        byte[] encryptedData = bops.toByteArray();
        String encodeToString = Base64.getEncoder().encodeToString(encryptedData);
        return encodeToString;
    }




    /**
     * 解密
     * @param key
     * @param data
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeyException
     * @throws NoSuchPaddingException
     * @throws InvalidKeySpecException
     * @throws BadPaddingException
     * @throws IllegalBlockSizeException
     * @throws IOException
     */
    public static String testDecrypt(String key,String data) throws NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, InvalidKeySpecException, IllegalBlockSizeException, BadPaddingException, IOException{
        byte[] decode = Base64.getDecoder().decode(key);
//      PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(decode); //java底层 RSA公钥只支持X509EncodedKeySpec这种格式
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(decode);
        KeyFactory kf = KeyFactory.getInstance(algorithm);
        PublicKey generatePublic = kf.generatePublic(x509EncodedKeySpec);
        Cipher ci = Cipher.getInstance(algorithm);
        ci.init(Cipher.DECRYPT_MODE,generatePublic);

        byte[] bytes = Base64.getDecoder().decode(data);
        int inputLen = bytes.length;
        int offLen = 0;
        int i = 0;
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        while(inputLen - offLen > 0){
            byte[] cache;
            if(inputLen - offLen > 128){
                cache = ci.doFinal(bytes,offLen,128);
            }else{
                cache = ci.doFinal(bytes,offLen,inputLen - offLen);
            }
            byteArrayOutputStream.write(cache);
            i++;
            offLen = 128 * i;

        }
        byteArrayOutputStream.close();
        byte[] byteArray = byteArrayOutputStream.toByteArray();
        return new String(byteArray);
    }



}