java之RSA和Base64加密帮助类

1、RSAUtils.java类
package com.sangfor.vpn.client.service.utils;
import java.io.BufferedReader;  
import java.io.ByteArrayOutputStream;  
import java.io.IOException;  
import java.io.InputStream;  
import java.io.InputStreamReader;  
import java.math.BigInteger;  
import java.security.KeyFactory;  
import java.security.KeyPair;  
import java.security.KeyPairGenerator;  
import java.security.NoSuchAlgorithmException;  
import java.security.PrivateKey;  
import java.security.PublicKey;  
import java.security.interfaces.RSAPrivateKey;  
import java.security.interfaces.RSAPublicKey;  
import java.security.spec.InvalidKeySpecException;  
import java.security.spec.PKCS8EncodedKeySpec;  
import java.security.spec.RSAPublicKeySpec;  
import java.security.spec.X509EncodedKeySpec;  
 
import javax.crypto.Cipher;  
 
/**
 * Created by wk on 2017/2/14.
 */  
 
public class RSAUtils {  
    private static String RSA = "RSA";  
    /** *//**  
     * RSA最大加密明文大小  
     */    
    private static final int MAX_ENCRYPT_BLOCK = 117;    
    /**
     * 随机生成RSA密钥对(默认密钥长度为1024)
     *
     * @return
     */  
    public static KeyPair generateRSAKeyPair()  
    {  
        return generateRSAKeyPair(1024);  
    }  
 
    /**
     * 随机生成RSA密钥对
     *
     * @param keyLength
     *            密钥长度，范围：512～2048<br>
     *            一般1024
     * @return
     */  
    public static KeyPair generateRSAKeyPair(int keyLength)  
    {  
        try  
        {  
            KeyPairGenerator kpg = KeyPairGenerator.getInstance(RSA);  
            kpg.initialize(keyLength);  
            return kpg.genKeyPair();  
        } catch (NoSuchAlgorithmException e)  
        {  
            e.printStackTrace();  
            return null;  
        }  
    }  
 
    /**
     * 用公钥加密 <br>
     * 每次加密的字节数，不能超过密钥的长度值减去11
     *
     * @param data
     *            需加密数据的byte数据
     * @param publicKey 公钥
     * @return 加密后的byte型数据
     */  
    public static byte[] encryptData(byte[] data, PublicKey publicKey)  
    {  
          
        try  
        {  
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");  
            // 编码前设定编码方式及密钥  
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);  
            // 传入编码数据并返回编码结果  
            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_ENCRYPT_BLOCK) {    
                    cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);    
                } else {    
                    cache = cipher.doFinal(data, offSet, inputLen - offSet);    
                }    
                out.write(cache, 0, cache.length);    
                i++;    
                offSet = i * MAX_ENCRYPT_BLOCK;    
            }    
            byte[] encryptedData = out.toByteArray();    
            out.close();    
            return encryptedData;    
        } catch (Exception e)  
        {  
            e.printStackTrace();  
            return null;  
        }  
    }  
 
    /**
     * 用私钥解密
     *
     * @param encryptedData
     *            经过encryptedData()加密返回的byte数据
     * @param privateKey
     *            私钥
     * @return
     */  
    public static byte[] decryptData(byte[] encryptedData, PrivateKey privateKey)  
    {  
        try  
        {  
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");  
            cipher.init(Cipher.DECRYPT_MODE, privateKey);  
            return cipher.doFinal(encryptedData);  
        } catch (Exception e)  
        {     
            e.printStackTrace();  
            return null;  
        }  
    }  
 
    /**
     * 通过公钥byte[](publicKey.getEncoded())将公钥还原，适用于RSA算法
     *
     * @param keyBytes
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */  
    public static PublicKey getPublicKey(byte[] keyBytes) throws NoSuchAlgorithmException,  
            InvalidKeySpecException  
    {  
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);  
        PublicKey publicKey = keyFactory.generatePublic(keySpec);  
        return publicKey;  
    }  
 
    /**
     * 通过私钥byte[]将公钥还原，适用于RSA算法
     *
     * @param keyBytes
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */  
    public static PrivateKey getPrivateKey(byte[] keyBytes) throws NoSuchAlgorithmException,  
            InvalidKeySpecException  
    {  
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);  
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);  
        return privateKey;  
    }  
 
    /**
     * 使用N、e值还原公钥
     *
     * @param modulus
     * @param publicExponent
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */  
    public static PublicKey getPublicKey(String modulus, String publicExponent)  
            throws NoSuchAlgorithmException, InvalidKeySpecException  
    {  
        BigInteger bigIntModulus = new BigInteger(modulus);  
        BigInteger bigIntPrivateExponent = new BigInteger(publicExponent);  
        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent);  
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);  
        PublicKey publicKey = keyFactory.generatePublic(keySpec);  
        return publicKey;  
    }  
 
    /**
     * 使用N、d值还原私钥
     *
     * @param modulus
     * @param privateExponent
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */  
    public static PrivateKey getPrivateKey(String modulus, String privateExponent)  
            throws NoSuchAlgorithmException, InvalidKeySpecException  
    {  
        BigInteger bigIntModulus = new BigInteger(modulus);  
        BigInteger bigIntPrivateExponent = new BigInteger(privateExponent);  
        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent);  
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);  
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);  
        return privateKey;  
    }  
 
    /**
     * 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 PublicKey loadPublicKey(String publicKeyStr) throws Exception  
    {  
        try  
        {  
            byte[] buffer = Base64Utils.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");  
        }  
    }  
 
    /**
     * 从字符串中加载私钥<br>
     * 加载时使用的是PKCS8EncodedKeySpec（PKCS#8编码的Key指令）。
     *
     * @param privateKeyStr
     * @return
     * @throws Exception
     */  
    public static PrivateKey loadPrivateKey(String privateKeyStr) throws Exception  
    {  
        try  
        {  
            byte[] buffer = Base64Utils.decode(privateKeyStr);  
            // X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);  
            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");  
        }  
    }  
 
    /**
     * 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 PublicKey loadPublicKey(InputStream in) throws Exception  
    {  
        try  
        {  
            return loadPublicKey(readKey(in));  
        } 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");  
        }  
    }  
 
    /**
     * 从文件中加载私钥
     *
     * @param in
     *            私钥文件名
     * @return 是否成功
     * @throws Exception
     */  
    public static PrivateKey loadPrivateKey(InputStream in) throws Exception  
    {  
        try  
        {  
            return loadPrivateKey(readKey(in));  
        } 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");  
        }  
    }  
 
    /**
     * 读取密钥信息
     *
     * @param in
     * @return
     * @throws IOException
     */  
    private static String readKey(InputStream in) throws IOException  
    {  
        BufferedReader br = new BufferedReader(new InputStreamReader(in));  
        String readLine = null;  
        StringBuilder sb = new StringBuilder();  
        while ((readLine = br.readLine()) != null)  
        {  
            if (readLine.charAt(0) == '-')  
            {  
                continue;  
            } else  
            {  
                sb.append(readLine);  
                sb.append('\r');  
            }  
        }  
 
        return sb.toString();  
    }  
 
    /**
     * 打印公钥信息
     *
     * @param publicKey
     */  
    public static void printPublicKeyInfo(PublicKey publicKey)  
    {  
        RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;  
        System.out.println("----------RSAPublicKey----------");  
        System.out.println("Modulus.length=" + rsaPublicKey.getModulus().bitLength());  
        System.out.println("Modulus=" + rsaPublicKey.getModulus().toString());  
        System.out.println("PublicExponent.length=" + rsaPublicKey.getPublicExponent().bitLength());  
        System.out.println("PublicExponent=" + rsaPublicKey.getPublicExponent().toString());  
    }  
 
    public static void printPrivateKeyInfo(PrivateKey privateKey)  
    {  
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) privateKey;  
        System.out.println("----------RSAPrivateKey ----------");  
        System.out.println("Modulus.length=" + rsaPrivateKey.getModulus().bitLength());  
        System.out.println("Modulus=" + rsaPrivateKey.getModulus().toString());  
        System.out.println("PrivateExponent.length=" + rsaPrivateKey.getPrivateExponent().bitLength());  
        System.out.println("PrivatecExponent=" + rsaPrivateKey.getPrivateExponent().toString());  
 
    }  

} 

2、Base64Utils.java类
package com.sangfor.vpn.client.service.utils;
 
import java.io.UnsupportedEncodingException;  
 
/**
 * Created by wk on 2017/2/14.
 */  
 
public class Base64Utils {  
    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 };  
 
    /**
     * 加密
     *
     * @param data
     * @return
     */  
    public static String encode(byte[] data)  
    {  
        StringBuffer sb = new StringBuffer();  
        int len = data.length;  
        int i = 0;  
        int b1, b2, b3;  
        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();  
    }  
 
    /**
     * 解密
     *
     * @param str
     * @return
     */  
    public static byte[] decode(String str)  
    {  
        try  
        {  
            return decodePrivate(str);  
        } catch (UnsupportedEncodingException e)  
        {  
            e.printStackTrace();  
        }  
        return new byte[]  
                {};  
    }  
 
    private static byte[] decodePrivate(String str) throws UnsupportedEncodingException  
    {  
        StringBuffer sb = new StringBuffer();  
        byte[] data = null;  
        data = str.getBytes("US-ASCII");  
        int len = data.length;  
        int i = 0;  
        int b1, b2, b3, b4;  
        while (i < len)  
        {  
 
            do  
            {  
                b1 = base64DecodeChars[data[i++]];  
            } while (i < len && b1 == -1);  
            if (b1 == -1)  
                break;  
 
            do  
            {  
                b2 = base64DecodeChars[data[i++]];  
            } while (i < len && b2 == -1);  
            if (b2 == -1)  
                break;  
            sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));  
 
            do  
            {  
                b3 = data[i++];  
                if (b3 == 61)  
                    return sb.toString().getBytes("iso8859-1");  
                b3 = base64DecodeChars[b3];  
            } while (i < len && b3 == -1);  
            if (b3 == -1)  
                break;  
            sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));  
 
            do  
            {  
                b4 = data[i++];  
                if (b4 == 61)  
                    return sb.toString().getBytes("iso8859-1");  
                b4 = base64DecodeChars[b4];  
            } while (i < len && b4 == -1);  
            if (b4 == -1)  
                break;  
            sb.append((char) (((b3 & 0x03) << 6) | b4));  
        }  
        return sb.toString().getBytes("iso8859-1");  
    }  
 
} 

3、SecurityUtils类
package com.sangfor.vpn.client.service.utils;
 
import java.io.FileInputStream;  
import java.io.FileNotFoundException;  
import java.io.InputStream;  
import java.security.PrivateKey;  
import java.security.PublicKey;  
 
public class SecurityUtils {  
    /**
     * 解密
     * @param cipherText 密文
     * @return 返回解密后的字符串
     * @throws Exception  
     */  
    public static String decrypt(String cipherText) throws Exception{  
         // 从文件中得到私钥  
        FileInputStream inPrivate = new FileInputStream(  
                SecurityUtils.class.getClassLoader().getResource("").getPath() + "/pkcs8_private_key.pem");  
        PrivateKey privateKey = RSAUtils.loadPrivateKey(inPrivate);  
        byte[] decryptByte = RSAUtils.decryptData(Base64Utils.decode(cipherText), privateKey);  
        String decryptStr = new String(decryptByte,"utf-8");  
        return decryptStr;  
    }  
    /**
     * 加密
     * @param plainTest 明文
     * @return  返回加密后的密文
     * @throws Exception  
     */  
    public static String encrypt(String plainTest) throws Exception{  
        PublicKey publicKey = RSAUtils.loadPublicKey(plainTest);  
        // 加密  
        byte[] encryptByte = RSAUtils.encryptData(plainTest.getBytes(), publicKey);  
        String afterencrypt = Base64Utils.encode(encryptByte);  
        return afterencrypt;  
    }  
    
    /**
     * 加密
     * @param plainTest 明文
     * @return  返回加密后的密文
     * @throws Exception  
     */  
    public static String encrypt(String plainTest, String key) throws Exception{  
        PublicKey publicKey = RSAUtils.loadPublicKey(key);  
        // 加密  
        byte[] encryptByte = RSAUtils.encryptData(plainTest.getBytes(), publicKey);  
        String afterencrypt = Base64Utils.encode(encryptByte);  
        return afterencrypt;  
    }  
} 




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