import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import java.io.*;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.security.*;
import 
 
java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Enumeration;

public class RSAUtil {

    public static final String SIGN_ALGORITHMS = "SHA1WithRSA";

    /**
     * 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;


    public static String sign(String content, String input_charset, Key key)
            throws UnsupportedEncodingException, Exception {
        Cipher cipher;
        try 
 
{
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
            cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] output = cipher.doFinal(content.getBytes(input_charset));
            return Base64.encode(output);
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("無此加密演算法");
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
            return null;
        } catch (InvalidKeyException e) {
            throw new Exception("加密公鑰非法,請檢查");
        } catch (IllegalBlockSizeException e) {
            throw new Exception("明文長度非法");
        } catch (BadPaddingException e) {
            throw new Exception("明文資料已損壞");
        }
    }

    public static String readFile(String filePath, String charSet) throws Exception {
        FileInputStream fileInputStream = new FileInputStream(filePath);
        try {
            FileChannel fileChannel = fileInputStream.getChannel();
            ByteBuffer byteBuffer = ByteBuffer.allocate((int) fileChannel.size());
            fileChannel.read(byteBuffer);
            byteBuffer.flip();
            return new String(byteBuffer.array(), charSet);
        } finally {
            fileInputStream.close();
        }

    }

    public static String getKey(String string) throws Exception {
        String content = readFile(string, "UTF8");
        return content.replaceAll("\\-{5}[\\w\\s]+\\-{5}[\\r\\n|\\n]", "");
    }

    public static boolean verifyByKeyPath(String content, String sign, String publicKeyPath, String input_charset) {
        try {
            return verifyByPublicKey(content, sign, getKey(publicKeyPath), input_charset);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }


    public static KeyInfo getPFXPrivateKey(String pfxPath, String password)
            throws KeyStoreException, NoSuchAlgorithmException,
            CertificateException, IOException, UnrecoverableKeyException {
        FileInputStream fis = new FileInputStream(pfxPath);
        KeyStore ks = KeyStore.getInstance("PKCS12");
        ks.load(fis, password.toCharArray());
        fis.close();
        Enumeration<String> enumas = ks.aliases();
        String keyAlias = null;
        if (enumas.hasMoreElements())// we are readin just one certificate.
{
            keyAlias = enumas.nextElement();
        }

        KeyInfo keyInfo = new KeyInfo();

        PrivateKey prikey = (PrivateKey) ks.getKey(keyAlias, password.toCharArray());
        Certificate cert = ks.getCertificate(keyAlias);
        PublicKey pubkey = cert.getPublicKey();

        keyInfo.privateKey = prikey;
        keyInfo.publicKey = pubkey;
        return keyInfo;
    }

    public static class KeyInfo {

        PublicKey publicKey;
        PrivateKey privateKey;

        public PublicKey getPublicKey() {
            return publicKey;
        }

        public PrivateKey getPrivateKey() {
            return privateKey;
        }
    }

    // =====================獲取公鑰私鑰===============================//
    //得到公鑰
public static PublicKey getPublicKey(String key) throws Exception {
        if (key == null) {
            throw new Exception("加密公鑰為空, 請設定");
        }
        byte[] buffer = Base64.decode(key);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
        return keyFactory.generatePublic(keySpec);
    }

    /**
     * 得到私鑰
     *
     * @param key 金鑰字串（經過base64編碼）
     * @throws Exception
     */
public static PrivateKey getPrivateKey(String key) throws Exception {
        byte[] keyBytes = buildPKCS8Key(key);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

    /**
     * 獲取公鑰
     *
     * @param filename
* @return
* @throws Exception
     */
public static PublicKey getPublicKeyFile(String filename) throws Exception {
        File f = new File(filename);
        FileInputStream fis = new FileInputStream(f);
        DataInputStream dis = new DataInputStream(fis);
        byte[] keyBytes = new byte[(int) f.length()];
        dis.readFully(keyBytes);
        dis.close();
        X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePublic(spec);
    }

    /**
     * 獲取私鑰
     *
     * @param filename
* @return
* @throws Exception
     */
public static PrivateKey getPrivateKeyFile(String filename) throws Exception {
        File f = new File(filename);
        FileInputStream fis = new FileInputStream(f);
        DataInputStream dis = new DataInputStream(fis);
        byte[] keyBytes = new byte[(int) f.length()];
        dis.readFully(keyBytes);
        dis.close();
        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(spec);
    }

    private static byte[] buildPKCS8Key(String privateKey) throws IOException {
        if (privateKey.contains("-----BEGIN PRIVATE KEY-----")) {
            return Base64.decode(privateKey.replaceAll("-----\\w+ PRIVATE KEY-----", ""));
        } else if (privateKey.contains("-----BEGIN RSA PRIVATE KEY-----")) {
            final byte[] innerKey = Base64.decode(privateKey.replaceAll("-----\\w+ RSA PRIVATE KEY-----", ""));
            final byte[] result = new byte[innerKey.length + 26];
            System.arraycopy(Base64.decode("MIIEvAIBADANBgkqhkiG9w0BAQEFAASCBKY="), 0, result, 0, 26);
            System.arraycopy(BigInteger.valueOf(result.length - 4).toByteArray(), 0, result, 2, 2);
            System.arraycopy(BigInteger.valueOf(innerKey.length).toByteArray(), 0, result, 24, 2);
            System.arraycopy(innerKey, 0, result, 26, innerKey.length);
            return result;
        } else {
            return Base64.decode(privateKey);
        }
    }


    // ==========================祕鑰加解密================================//
    //私鑰加密 呼叫方法
public static String signByPrivate(String content, String privateKey,
                                       String input_charset) throws Exception {
        if (privateKey == null) {
            throw new Exception("加密私鑰為空, 請設定");
        }
        PrivateKey privateKeyInfo = getPrivateKey(privateKey);
        java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
        signature.initSign(privateKeyInfo);
        signature.update(content.getBytes(input_charset));
        return Base64.encode(signature.sign());
    }

    /**
     * RSA驗簽名檢查
     *
     * @param content       待簽名資料
     * @param sign          簽名值
     * @param publicKey     支付寶公鑰
     * @param input_charset 編碼格式
     * @return 布林值
     *///使用私鑰加密 公鑰解密驗證 呼叫方法
public static boolean verifyByPublicKey(String content, String sign, String publicKey, String input_charset) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] encodedKey = Base64.decode(publicKey);
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
            java.security.Signature signature = java.security.Signature
                    .getInstance(SIGN_ALGORITHMS);
            signature.initVerify(pubKey);
            signature.update(content.getBytes(input_charset));
            boolean bverify = signature.verify(Base64.decode(sign));
            return bverify;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;

    }

    /**
     * <P>     * 私鑰解密
     * </p>     *
     * @param encryptedData 已加密資料
     * @param privateKey    私鑰(BASE64編碼)
     * @return
* @throws Exception
     */
public static String decryptByPrivateKey(String encryptedData, String privateKey) throws Exception {

        byte[] encrypt = Base64.decode(encryptedData);//轉換加密資料型別轉換
PrivateKey privateK = getPrivateKey(privateKey);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encrypt.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對資料分段解密
while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encrypt, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encrypt, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return new String(decryptedData);
    }

    /**
     * <p>     * 公鑰加密
     * </p>     *
     * @param data      源資料
     * @param publicKey 公鑰(BASE64編碼)
     * @return
* @throws Exception
     */
public static String encryptByPublicKey(String data, String publicKey) throws Exception {
        byte[] encryptDate = data.getBytes("UTF-8");
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, getPublicKey(publicKey));
        int inputLen = encryptDate.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對資料分段加密
while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(encryptDate, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptDate, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();

        return Base64.encode(encryptedData);
    }

    /**
     * 公鑰加密，私鑰驗證
     * @param content       未加密的資料
     * @param sign          加密後的資料
     * @param privateKey    私鑰
     * @return
* @throws Exception
     */
public static boolean verifyByPrivateKey(String content, String sign, String privateKey) throws Exception {
        String data = decryptByPrivateKey(sign, privateKey);
        if (content.equals(data)) {
            return true;
        }
        return false;
    }
}

public class Base64  
{  
    private static char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',  
            'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',  
            'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };  
  
    private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55,  
            56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,  
            21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,  
            47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };  
  
    private Base64(){}  
  
    public static synchronized String encode(byte[] data)  
    {  
        int len = data.length;  
        int i = 0;  
        int b1, b2, b3;  
        StringBuilder sb = new StringBuilder(len);  
  
        while (i < len)  
        {  
            b1 = data[i++] & 0xff;  
            if (i == len)  
            {  
                sb.append(base64EncodeChars[b1 >>> 2]);  
                sb.append(base64EncodeChars[(b1 & 0x3) << 4]);  
                sb.append("==");  
                break;  
            }  
            b2 = data[i++] & 0xff;  
            if (i == len)  
            {  
                sb.append(base64EncodeChars[b1 >>> 2]);  
                sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
                sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);  
                sb.append("=");  
                break;  
            }  
            b3 = data[i++] & 0xff;  
            sb.append(base64EncodeChars[b1 >>> 2]);  
            sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
            sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);  
            sb.append(base64EncodeChars[b3 & 0x3f]);  
        }  
        return sb.toString();  
    }  
  
    public static synchronized byte[] decode(String str)  
    {  
        byte[] data = str.getBytes();  
        int len = data.length;  
        ByteArrayOutputStream buf = new ByteArrayOutputStream(len);  
        int i = 0;  
        int b1, b2, b3, b4;  
  
        while (i < len)  
        {  
  
            /* b1 */  
do  
{  
                b1 = base64DecodeChars[data[i++]];  
            }  
            while (i < len && b1 == -1);  
            if (b1 == -1)  
            {  
                break;  
            }  
  
            /* b2 */  
do  
{  
                b2 = base64DecodeChars[data[i++]];  
            }  
            while (i < len && b2 == -1);  
            if (b2 == -1)  
            {  
                break;  
            }  
            buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));  
  
            /* b3 */  
do  
{  
                b3 = data[i++];  
                if (b3 == 61)  
                {  
                    return buf.toByteArray();  
                }  
                b3 = base64DecodeChars[b3];  
            }  
            while (i < len && b3 == -1);  
            if (b3 == -1)  
            {  
                break;  
            }  
            buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));  
  
            /* b4 */  
do  
{  
                b4 = data[i++];  
                if (b4 == 61)  
                {  
                    return buf.toByteArray();  
                }  
                b4 = base64DecodeChars[b4];  
            }  
            while (i < len && b4 == -1);  
            if (b4 == -1)  
            {  
                break;  
            }  
            buf.write((int) (((b3 & 0x03) << 6) | b4));  
        }  
        return buf.toByteArray();  
    }

   }