Java使用RSA加密解密签名及校验

Java使用RSA加密解密签名及校验

由于项目要用到非对称加密解密签名校验什么的，于是参考《Java加密解密的艺术》写一个RSA进行加密解密签名及校验的Demo，代码很简单，特此分享！

RSA加密解密类：

 package com.ihep;

 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.security.InvalidKeyException;
 import java.security.KeyFactory;
 import java.security.KeyPair;
 import java.security.KeyPairGenerator;
 import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;

 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 javax.crypto.BadPaddingException;
 import javax.crypto.Cipher;
 import javax.crypto.IllegalBlockSizeException;
 import javax.crypto.NoSuchPaddingException;

 import com.fcplay.Base64;

 public class RSAEncrypt {
     /**
      * 字节数据转字符串专用集合
      */
     private static final char[] HEX_CHAR = { '0', '1', '2', '3', '4', '5', '6',
             '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

     /**
      * 随机生成密钥对
      */
     public static void genKeyPair(String filePath) {
         // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
         KeyPairGenerator keyPairGen = null;
         try {
             keyPairGen = KeyPairGenerator.getInstance("RSA");
         } catch (NoSuchAlgorithmException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         // 初始化密钥对生成器，密钥大小为96-1024位
         keyPairGen.initialize(1024,new SecureRandom());
         // 生成一个密钥对，保存在keyPair中
         KeyPair keyPair = keyPairGen.generateKeyPair();
         // 得到私钥
         RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
         // 得到公钥
         RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
         try {
             // 得到公钥字符串
             String publicKeyString = Base64.encode(publicKey.getEncoded());
             // 得到私钥字符串
             String privateKeyString = Base64.encode(privateKey.getEncoded());
             // 将密钥对写入到文件
             FileWriter pubfw = new FileWriter(filePath + "/publicKey.keystore");
             FileWriter prifw = new FileWriter(filePath + "/privateKey.keystore");
             BufferedWriter pubbw = new BufferedWriter(pubfw);
             BufferedWriter pribw = new BufferedWriter(prifw);
             pubbw.write(publicKeyString);
             pribw.write(privateKeyString);
             pubbw.flush();
             pubbw.close();
             pubfw.close();
             pribw.flush();
             pribw.close();
             prifw.close();
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     /**
      * 从文件中输入流中加载公钥
      *
      * @param in
      *            公钥输入流
      * @throws Exception
      *             加载公钥时产生的异常
      */
     public static String loadPublicKeyByFile(String path) throws Exception {
         try {
             BufferedReader br = new BufferedReader(new FileReader(path
                     + "/publicKey.keystore"));
             String readLine = null;
             StringBuilder sb = new StringBuilder();
             while ((readLine = br.readLine()) != null) {
                 sb.append(readLine);
             }
             br.close();
             return sb.toString();
         } catch (IOException e) {
             throw new Exception("公钥数据流读取错误");
         } catch (NullPointerException e) {
             throw new Exception("公钥输入流为空");
         }
     }

     /**
      * 从字符串中加载公钥
      *
      * @param publicKeyStr
      *            公钥数据字符串
      * @throws Exception
      *             加载公钥时产生的异常
      */
     public static RSAPublicKey loadPublicKeyByStr(String publicKeyStr)
             throws Exception {
         try {
             byte[] buffer = Base64.decode(publicKeyStr);
             KeyFactory keyFactory = KeyFactory.getInstance("RSA");
             X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
             return (RSAPublicKey) keyFactory.generatePublic(keySpec);
         } catch (NoSuchAlgorithmException e) {
             throw new Exception("无此算法");
         } catch (InvalidKeySpecException e) {
             throw new Exception("公钥非法");
         } catch (NullPointerException e) {
             throw new Exception("公钥数据为空");
         }
     }

     /**
      * 从文件中加载私钥
      *
      * @param keyFileName
      *            私钥文件名
      * @return 是否成功
      * @throws Exception
      */
     public static String loadPrivateKeyByFile(String path) throws Exception {
         try {
             BufferedReader br = new BufferedReader(new FileReader(path
                     + "/privateKey.keystore"));
             String readLine = null;
             StringBuilder sb = new StringBuilder();
             while ((readLine = br.readLine()) != null) {
                 sb.append(readLine);
             }
             br.close();
             return sb.toString();
         } catch (IOException e) {
             throw new Exception("私钥数据读取错误");
         } catch (NullPointerException e) {
             throw new Exception("私钥输入流为空");
         }
     }

     public static RSAPrivateKey loadPrivateKeyByStr(String privateKeyStr)
             throws Exception {
         try {
             byte[] buffer = Base64.decode(privateKeyStr);
             PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
             KeyFactory keyFactory = KeyFactory.getInstance("RSA");
             return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
         } catch (NoSuchAlgorithmException e) {
             throw new Exception("无此算法");
         } catch (InvalidKeySpecException e) {
             throw new Exception("私钥非法");
         } catch (NullPointerException e) {
             throw new Exception("私钥数据为空");
         }
     }

     /**
      * 公钥加密过程
      *
      * @param publicKey
      *            公钥
      * @param plainTextData
      *            明文数据
      * @return
      * @throws Exception
      *             加密过程中的异常信息
      */
     public static byte[] encrypt(RSAPublicKey publicKey, byte[] plainTextData)
             throws Exception {
         if (publicKey == null) {
             throw new Exception("加密公钥为空, 请设置");
         }
         Cipher cipher = null;
         try {
             // 使用默认RSA
             cipher = Cipher.getInstance("RSA");
             // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
             cipher.init(Cipher.ENCRYPT_MODE, publicKey);
             byte[] output = cipher.doFinal(plainTextData);
             return output;
         } catch (NoSuchAlgorithmException e) {
             throw new Exception("无此加密算法");
         } catch (NoSuchPaddingException e) {
             e.printStackTrace();
             return null;
         } catch (InvalidKeyException e) {
             throw new Exception("加密公钥非法,请检查");
         } catch (IllegalBlockSizeException e) {
             throw new Exception("明文长度非法");
         } catch (BadPaddingException e) {
             throw new Exception("明文数据已损坏");
         }
     }

     /**
      * 私钥加密过程
      *
      * @param privateKey
      *            私钥
      * @param plainTextData
      *            明文数据
      * @return
      * @throws Exception
      *             加密过程中的异常信息
      */
     public static byte[] encrypt(RSAPrivateKey privateKey, byte[] plainTextData)
             throws Exception {
         if (privateKey == null) {
             throw new Exception("加密私钥为空, 请设置");
         }
         Cipher cipher = null;
         try {
             // 使用默认RSA
             cipher = Cipher.getInstance("RSA");
             cipher.init(Cipher.ENCRYPT_MODE, privateKey);
             byte[] output = cipher.doFinal(plainTextData);
             return output;
         } catch (NoSuchAlgorithmException e) {
             throw new Exception("无此加密算法");
         } catch (NoSuchPaddingException e) {
             e.printStackTrace();
             return null;
         } catch (InvalidKeyException e) {
             throw new Exception("加密私钥非法,请检查");
         } catch (IllegalBlockSizeException e) {
             throw new Exception("明文长度非法");
         } catch (BadPaddingException e) {
             throw new Exception("明文数据已损坏");
         }
     }

     /**
      * 私钥解密过程
      *
      * @param privateKey
      *            私钥
      * @param cipherData
      *            密文数据
      * @return 明文
      * @throws Exception
      *             解密过程中的异常信息
      */
     public static byte[] decrypt(RSAPrivateKey privateKey, byte[] cipherData)
             throws Exception {
         if (privateKey == null) {
             throw new Exception("解密私钥为空, 请设置");
         }
         Cipher cipher = null;
         try {
             // 使用默认RSA
             cipher = Cipher.getInstance("RSA");
             // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
             cipher.init(Cipher.DECRYPT_MODE, privateKey);
             byte[] output = cipher.doFinal(cipherData);
             return output;
         } catch (NoSuchAlgorithmException e) {
             throw new Exception("无此解密算法");
         } catch (NoSuchPaddingException e) {
             e.printStackTrace();
             return null;
         } catch (InvalidKeyException e) {
             throw new Exception("解密私钥非法,请检查");
         } catch (IllegalBlockSizeException e) {
             throw new Exception("密文长度非法");
         } catch (BadPaddingException e) {
             throw new Exception("密文数据已损坏");
         }
     }

     /**
      * 公钥解密过程
      *
      * @param publicKey
      *            公钥
      * @param cipherData
      *            密文数据
      * @return 明文
      * @throws Exception
      *             解密过程中的异常信息
      */
     public static byte[] decrypt(RSAPublicKey publicKey, byte[] cipherData)
             throws Exception {
         if (publicKey == null) {
             throw new Exception("解密公钥为空, 请设置");
         }
         Cipher cipher = null;
         try {
             // 使用默认RSA
             cipher = Cipher.getInstance("RSA");
             // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
             cipher.init(Cipher.DECRYPT_MODE, publicKey);
             byte[] output = cipher.doFinal(cipherData);
             return output;
         } catch (NoSuchAlgorithmException e) {
             throw new Exception("无此解密算法");
         } catch (NoSuchPaddingException e) {
             e.printStackTrace();
             return null;
         } catch (InvalidKeyException e) {
             throw new Exception("解密公钥非法,请检查");
         } catch (IllegalBlockSizeException e) {
             throw new Exception("密文长度非法");
         } catch (BadPaddingException e) {
             throw new Exception("密文数据已损坏");
         }
     }

     /**
      * 字节数据转十六进制字符串
      *
      * @param data
      *            输入数据
      * @return 十六进制内容
      */
     public static String byteArrayToString(byte[] data) {
         StringBuilder stringBuilder = new StringBuilder();
         for (int i = 0; i < data.length; i++) {
             // 取出字节的高四位 作为索引得到相应的十六进制标识符 注意无符号右移
             stringBuilder.append(HEX_CHAR[(data[i] & 0xf0) >>> 4]);
             // 取出字节的低四位 作为索引得到相应的十六进制标识符
             stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);
             if (i < data.length - 1) {
                 stringBuilder.append(' ');
             }
         }
         return stringBuilder.toString();
     }
 }

签名及校验类：

 package com.ihep;

 import java.security.KeyFactory;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.spec.PKCS8EncodedKeySpec;
 import java.security.spec.X509EncodedKeySpec;



 /**
  * RSA签名验签类
  */
 public class RSASignature{

     /**
      * 签名算法
      */
     public static final String SIGN_ALGORITHMS = "SHA1WithRSA";

     /**
     * RSA签名
     * @param content 待签名数据
     * @param privateKey 商户私钥
     * @param encode 字符集编码
     * @return 签名值
     */
     public static String sign(String content, String privateKey, String encode)
     {
         try
         {
             PKCS8EncodedKeySpec priPKCS8    = new PKCS8EncodedKeySpec( Base64.decode(privateKey) );

             KeyFactory keyf                 = KeyFactory.getInstance("RSA");
             PrivateKey priKey               = keyf.generatePrivate(priPKCS8);

             java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);

             signature.initSign(priKey);
             signature.update( content.getBytes(encode));

             byte[] signed = signature.sign();

             return Base64.encode(signed);
         }
         catch (Exception e)
         {
             e.printStackTrace();
         }

         return null;
     }

     public static String sign(String content, String privateKey)
     {
         try
         {
             PKCS8EncodedKeySpec priPKCS8    = new PKCS8EncodedKeySpec( Base64.decode(privateKey) );
             KeyFactory keyf = KeyFactory.getInstance("RSA");
             PrivateKey priKey = keyf.generatePrivate(priPKCS8);
             java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
             signature.initSign(priKey);
             signature.update( content.getBytes());
             byte[] signed = signature.sign();
             return Base64.encode(signed);
         }
         catch (Exception e)
         {
             e.printStackTrace();
         }
         return null;
     }

     /**
     * RSA验签名检查
     * @param content 待签名数据
     * @param sign 签名值
     * @param publicKey 分配给开发商公钥
     * @param encode 字符集编码
     * @return 布尔值
     */
     public static boolean doCheck(String content, String sign, String publicKey,String encode)
     {
         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(encode) );

             boolean bverify = signature.verify( Base64.decode(sign) );
             return bverify;

         }
         catch (Exception e)
         {
             e.printStackTrace();
         }

         return false;
     }

     public static boolean doCheck(String content, String sign, String publicKey)
     {
         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() );

             boolean bverify = signature.verify( Base64.decode(sign) );
             return bverify;

         }
         catch (Exception e)
         {
             e.printStackTrace();
         }

         return false;
     }

 }

再来一个Base64的类，当然你也可以用commons-codec-1.9.jar

 package com.ihep;

 public final class Base64 {

     static private final int     BASELENGTH           = 128;
     static private final int     LOOKUPLENGTH         = 64;
     static private final int     TWENTYFOURBITGROUP   = 24;
     static private final int     EIGHTBIT             = 8;
     static private final int     SIXTEENBIT           = 16;
     static private final int     FOURBYTE             = 4;
     static private final int     SIGN                 = -128;
     static private final char    PAD                  = '=';
     static private final boolean fDebug               = false;
     static final private byte[]  base64Alphabet       = new byte[BASELENGTH];
     static final private char[]  lookUpBase64Alphabet = new char[LOOKUPLENGTH];

     static {
         for (int i = 0; i < BASELENGTH; ++i) {
             base64Alphabet[i] = -1;
         }
         for (int i = 'Z'; i >= 'A'; i--) {
             base64Alphabet[i] = (byte) (i - 'A');
         }
         for (int i = 'z'; i >= 'a'; i--) {
             base64Alphabet[i] = (byte) (i - 'a' + 26);
         }

         for (int i = '9'; i >= '0'; i--) {
             base64Alphabet[i] = (byte) (i - '0' + 52);
         }

         base64Alphabet['+'] = 62;
         base64Alphabet['/'] = 63;

         for (int i = 0; i <= 25; i++) {
             lookUpBase64Alphabet[i] = (char) ('A' + i);
         }

         for (int i = 26, j = 0; i <= 51; i++, j++) {
             lookUpBase64Alphabet[i] = (char) ('a' + j);
         }

         for (int i = 52, j = 0; i <= 61; i++, j++) {
             lookUpBase64Alphabet[i] = (char) ('0' + j);
         }
         lookUpBase64Alphabet[62] = (char) '+';
         lookUpBase64Alphabet[63] = (char) '/';

     }

     private static boolean isWhiteSpace(char octect) {
         return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
     }

     private static boolean isPad(char octect) {
         return (octect == PAD);
     }

     private static boolean isData(char octect) {
         return (octect < BASELENGTH && base64Alphabet[octect] != -1);
     }

     /**
      * Encodes hex octects into Base64
      *
      * @param binaryData Array containing binaryData
      * @return Encoded Base64 array
      */
     public static String encode(byte[] binaryData) {

         if (binaryData == null) {
             return null;
         }

         int lengthDataBits = binaryData.length * EIGHTBIT;
         if (lengthDataBits == 0) {
             return "";
         }

         int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
         int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
         int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
         char encodedData[] = null;

         encodedData = new char[numberQuartet * 4];

         byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;

         int encodedIndex = 0;
         int dataIndex = 0;
         if (fDebug) {
             System.out.println("number of triplets = " + numberTriplets);
         }

         for (int i = 0; i < numberTriplets; i++) {
             b1 = binaryData[dataIndex++];
             b2 = binaryData[dataIndex++];
             b3 = binaryData[dataIndex++];

             if (fDebug) {
                 System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
             }

             l = (byte) (b2 & 0x0f);
             k = (byte) (b1 & 0x03);

             byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
             byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
             byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);

             if (fDebug) {
                 System.out.println("val2 = " + val2);
                 System.out.println("k4   = " + (k << 4));
                 System.out.println("vak  = " + (val2 | (k << 4)));
             }

             encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
             encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
             encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
             encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
         }

         // form integral number of 6-bit groups
         if (fewerThan24bits == EIGHTBIT) {
             b1 = binaryData[dataIndex];
             k = (byte) (b1 & 0x03);
             if (fDebug) {
                 System.out.println("b1=" + b1);
                 System.out.println("b1<<2 = " + (b1 >> 2));
             }
             byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
             encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
             encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
             encodedData[encodedIndex++] = PAD;
             encodedData[encodedIndex++] = PAD;
         } else if (fewerThan24bits == SIXTEENBIT) {
             b1 = binaryData[dataIndex];
             b2 = binaryData[dataIndex + 1];
             l = (byte) (b2 & 0x0f);
             k = (byte) (b1 & 0x03);

             byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
             byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);

             encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
             encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
             encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
             encodedData[encodedIndex++] = PAD;
         }

         return new String(encodedData);
     }

     /**
      * Decodes Base64 data into octects
      *
      * @param encoded string containing Base64 data
      * @return Array containind decoded data.
      */
     public static byte[] decode(String encoded) {

         if (encoded == null) {
             return null;
         }

         char[] base64Data = encoded.toCharArray();
         // remove white spaces
         int len = removeWhiteSpace(base64Data);

         if (len % FOURBYTE != 0) {
             return null;//should be divisible by four
         }

         int numberQuadruple = (len / FOURBYTE);

         if (numberQuadruple == 0) {
             return new byte[0];
         }

         byte decodedData[] = null;
         byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
         char d1 = 0, d2 = 0, d3 = 0, d4 = 0;

         int i = 0;
         int encodedIndex = 0;
         int dataIndex = 0;
         decodedData = new byte[(numberQuadruple) * 3];

         for (; i < numberQuadruple - 1; i++) {

             if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
                 || !isData((d3 = base64Data[dataIndex++]))
                 || !isData((d4 = base64Data[dataIndex++]))) {
                 return null;
             }//if found "no data" just return null

             b1 = base64Alphabet[d1];
             b2 = base64Alphabet[d2];
             b3 = base64Alphabet[d3];
             b4 = base64Alphabet[d4];

             decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
             decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
             decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
         }

         if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
             return null;//if found "no data" just return null
         }

         b1 = base64Alphabet[d1];
         b2 = base64Alphabet[d2];

         d3 = base64Data[dataIndex++];
         d4 = base64Data[dataIndex++];
         if (!isData((d3)) || !isData((d4))) {//Check if they are PAD characters
             if (isPad(d3) && isPad(d4)) {
                 if ((b2 & 0xf) != 0)//last 4 bits should be zero
                 {
                     return null;
                 }
                 byte[] tmp = new byte[i * 3 + 1];
                 System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                 tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                 return tmp;
             } else if (!isPad(d3) && isPad(d4)) {
                 b3 = base64Alphabet[d3];
                 if ((b3 & 0x3) != 0)//last 2 bits should be zero
                 {
                     return null;
                 }
                 byte[] tmp = new byte[i * 3 + 2];
                 System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                 tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                 tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                 return tmp;
             } else {
                 return null;
             }
         } else { //No PAD e.g 3cQl
             b3 = base64Alphabet[d3];
             b4 = base64Alphabet[d4];
             decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
             decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
             decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);

         }

         return decodedData;
     }

     /**
      * remove WhiteSpace from MIME containing encoded Base64 data.
      *
      * @param data  the byte array of base64 data (with WS)
      * @return      the new length
      */
     private static int removeWhiteSpace(char[] data) {
         if (data == null) {
             return 0;
         }

         // count characters that's not whitespace
         int newSize = 0;
         int len = data.length;
         for (int i = 0; i < len; i++) {
             if (!isWhiteSpace(data[i])) {
                 data[newSize++] = data[i];
             }
         }
         return newSize;
     }
 }

最后是一个MainTest：

 package com.ihep;

 public class MainTest {

     public static void main(String[] args) throws Exception {
         String filepath="G:/tmp/";

         //RSAEncrypt.genKeyPair(filepath);


         System.out.println("--------------公钥加密私钥解密过程-------------------");
         String plainText="ihep_公钥加密私钥解密";
         //公钥加密过程
         byte[] cipherData=RSAEncrypt.encrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)),plainText.getBytes());
         String cipher=Base64.encode(cipherData);
         //私钥解密过程
         byte[] res=RSAEncrypt.decrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)), Base64.decode(cipher));
         String restr=new String(res);
         System.out.println("原文："+plainText);
         System.out.println("加密："+cipher);
         System.out.println("解密："+restr);
         System.out.println();

         System.out.println("--------------私钥加密公钥解密过程-------------------");
         plainText="ihep_私钥加密公钥解密";
         //私钥加密过程
         cipherData=RSAEncrypt.encrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)),plainText.getBytes());
         cipher=Base64.encode(cipherData);
         //公钥解密过程
         res=RSAEncrypt.decrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)), Base64.decode(cipher));
         restr=new String(res);
         System.out.println("原文："+plainText);
         System.out.println("加密："+cipher);
         System.out.println("解密："+restr);
         System.out.println();

         System.out.println("---------------私钥签名过程------------------");
         String content="ihep_这是用于签名的原始数据";
         String signstr=RSASignature.sign(content,RSAEncrypt.loadPrivateKeyByFile(filepath));
         System.out.println("签名原串："+content);
         System.out.println("签名串："+signstr);
         System.out.println();

         System.out.println("---------------公钥校验签名------------------");
         System.out.println("签名原串："+content);
         System.out.println("签名串："+signstr);

         System.out.println("验签结果："+RSASignature.doCheck(content, signstr, RSAEncrypt.loadPublicKeyByFile(filepath)));
         System.out.println();

     }
 }

看看运行截图：