Android 网络请求加密

转载请注明出处：

http://blog.csdn.net/aa464971/article/details/51034462

本文以Android客户端加密提交数据到Java服务端后进行解密为例子。

生成RSA公钥和密钥的方法请参考：

http://blog.csdn.net/aa464971/article/details/51035200

Android端的加密思路需要4步：

1.生成AES密钥；

2.使用RSA公钥加密刚刚生成的AES密钥；

3.再使用第1步生成的AES密钥，通过AES加密需要提交给服务端的数据；

4.将第2与第3生成的内容传给服务端。

JAVA服务端的解密思路只需3步：

1.获取到客户端传过来的AES密钥密文和内容密文；

2.使用RSA私钥解密从客户端拿到的AES密钥密文；

3.再使用第2步解密出来的明文密钥，通过AES解密内容的密文。

AES的代码可以在JAVA和Android上通用

package com.dyhdyh.encrypt;

import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * AES
 * @author dengyuhan
 * @create 2016/3/31 15:43
 */
public class AES {
    // /** 算法/模式/填充 **/
    private static final String CipherMode = "AES/ECB/PKCS5Padding";
    // private static final String CipherMode = "AES";

    /**
     * 生成一个AES密钥对象
     * @return
     */
    public static SecretKeySpec generateKey(){
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom());
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            return key;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 生成一个AES密钥字符串
     * @return
     */
    public static String generateKeyString(){
        return byte2hex(generateKey().getEncoded());
    }

    /**
     * 加密字节数据
     * @param content
     * @param key
     * @return
     */
    public static byte[] encrypt(byte[] content,byte[] key) {
        try {
            Cipher cipher = Cipher.getInstance(CipherMode);
            cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "AES"));
            byte[] result = cipher.doFinal(content);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 通过byte[]类型的密钥加密String
     * @param content
     * @param key
     * @return 16进制密文字符串
     */
    public static String encrypt(String content,byte[] key) {
        try {
            Cipher cipher = Cipher.getInstance(CipherMode);
            cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "AES"));
            byte[] data = cipher.doFinal(content.getBytes("UTF-8"));
            String result = byte2hex(data);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 通过String类型的密钥加密String
     * @param content
     * @param key
     * @return 16进制密文字符串
     */
    public static String encrypt(String content,String key) {
        byte[] data = null;
        try {
            data = content.getBytes("UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
        }
        data = encrypt(data,new SecretKeySpec(hex2byte(key), "AES").getEncoded());
        String result = byte2hex(data);
        return result;
    }

    /**
     * 通过byte[]类型的密钥解密byte[]
     * @param content
     * @param key
     * @return
     */
    public static byte[] decrypt(byte[] content,byte[] key) {
        try {
            Cipher cipher = Cipher.getInstance(CipherMode);
            cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"));
            byte[] result = cipher.doFinal(content);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 通过String类型的密钥 解密String类型的密文
     * @param content
     * @param key
     * @return
     */
    public static String decrypt(String content, String key) {
        byte[] data = null;
        try {
            data = hex2byte(content);
        } catch (Exception e) {
            e.printStackTrace();
        }
        data = decrypt(data, hex2byte(key));
        if (data == null)
            return null;
        String result = null;
        try {
            result = new String(data, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 通过byte[]类型的密钥 解密String类型的密文
     * @param content
     * @param key
     * @return
     */
    public static String decrypt(String content,byte[] key) {
        try {
            Cipher cipher = Cipher.getInstance(CipherMode);
            cipher.init(Cipher.DECRYPT_MODE,new SecretKeySpec(key, "AES"));
            byte[] data = cipher.doFinal(hex2byte(content));
            return new String(data, "UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 字节数组转成16进制字符串
     * @param b
     * @return
     */
    public static String byte2hex(byte[] b) { // 一个字节的数，
        StringBuffer sb = new StringBuffer(b.length * 2);
        String tmp = "";
        for (int n = 0; n < b.length; n++) {
            // 整数转成十六进制表示
            tmp = (Integer.toHexString(b[n] & 0XFF));
            if (tmp.length() == 1) {
                sb.append("0");
            }
            sb.append(tmp);
        }
        return sb.toString().toUpperCase(); // 转成大写
    }

    /**
     * 将hex字符串转换成字节数组
     * @param inputString
     * @return
     */
    private static byte[] hex2byte(String inputString) {
        if (inputString == null || inputString.length() < 2) {
            return new byte[0];
        }
        inputString = inputString.toLowerCase();
        int l = inputString.length() / 2;
        byte[] result = new byte[l];
        for (int i = 0; i < l; ++i) {
            String tmp = inputString.substring(2 * i, 2 * i + 2);
            result[i] = (byte) (Integer.parseInt(tmp, 16) & 0xFF);
        }
        return result;
    }
}

Android - RSA实现

package com.dyhdyh.encrypt;

import android.util.Base64;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
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.Cipher;

/**
 * 用于Android平台的RSA加密解密
 *
 * @desc
 * @author dengyuhan
 * @create 2016-3-31 下午2:36:18
 */
public class RSA {
    private static final String ALGORITHM = "RSA";
    private static final String TRANSFORMATION = "RSA";

    /**
     * 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 RSAPublicKey loadPublicKey(InputStream in) throws Exception {
        try {
            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 loadPublicKey(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
     * @return
     * @throws Exception
     *             加载公钥时产生的异常
     */
    public static RSAPublicKey loadPublicKey(String publicKeyStr)
            throws Exception {
        try {
            byte[] buffer = Base64.decode(publicKeyStr, Base64.DEFAULT);
            KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
            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 in
     *            私钥输入流
     * @return
     * @throws Exception
     */
    public static RSAPrivateKey loadPrivateKey(InputStream in) throws Exception {
        try {
            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 loadPrivateKey(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");
        }
    }

    /**
     * 从字符串中加载私钥
     *
     * @desc
     * @param privateKeyStr
     *            私钥字符串
     * @return
     * @throws Exception
     */
    public static RSAPrivateKey loadPrivateKey(String privateKeyStr)
            throws Exception {
        try {
            byte[] buffer = Base64.decode(privateKeyStr, Base64.DEFAULT);
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
            KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
            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
     *
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static String encryptByPublicKey(String data, RSAPublicKey publicKey)
            throws Exception {
        // 模长
        int key_len = publicKey.getModulus().bitLength() / 8;
        // 加密数据长度 <= 模长-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
        // 如果明文长度大于模长-11则要分组加密
        for (String s : datas) {
            mi += bcd2Str(encryptByPublicKey(s.getBytes(), publicKey));
        }
        return mi;
    }

    /**
     * 公钥加密
     * @desc
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, RSAPublicKey publicKey)
            throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * 私钥加密
     * @desc
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data,
            RSAPrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }


    /**
     * 私钥加密
     * @desc
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static String encryptByPrivateKey(String data,
            RSAPrivateKey privateKey) throws Exception {
        // 模长
        int key_len = privateKey.getModulus().bitLength() / 8;
        // 加密数据长度 <= 模长-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
        // 如果明文长度大于模长-11则要分组加密
        for (String s : datas) {
            mi += bcd2Str(encryptByPrivateKey(s.getBytes(), privateKey));
        }
        return mi;
    }

    /**
     * 私钥解密
     *
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static String decryptByPrivateKey(String data,
            RSAPrivateKey privateKey) throws Exception {
        // 模长
        int key_len = privateKey.getModulus().bitLength() / 8;
        byte[] bytes = data.getBytes();
        byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
        // 如果密文长度大于模长则要分组解密
        String ming = "";
        byte[][] arrays = splitArray(bcd, key_len);
        for (byte[] arr : arrays) {
            ming += new String(decryptByPrivateKey(arr, privateKey));
        }
        return ming;
    }

    /**
     * 私钥解密
     * @desc
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] data,
            RSAPrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 公钥解密
     * @desc
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static String decryptByPublicKey(String data,
            RSAPublicKey publicKey) throws Exception {
        // 模长
        int key_len = publicKey.getModulus().bitLength() / 8;
        byte[] bytes = data.getBytes();
        byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
        // 如果密文长度大于模长则要分组解密
        String ming = "";
        byte[][] arrays = splitArray(bcd, key_len);
        for (byte[] arr : arrays) {
            ming += new String(decryptByPublicKey(arr, publicKey));
        }
        return ming;
    }

    /**
     * 公钥解密
     * @desc
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data,
            RSAPublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * ASCII码转BCD码
     *
     */
    private static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
        byte[] bcd = new byte[asc_len / 2];
        int j = 0;
        for (int i = 0; i < (asc_len + 1) / 2; i++) {
            bcd[i] = asc_to_bcd(ascii[j++]);
            bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
        }
        return bcd;
    }

    private static byte asc_to_bcd(byte asc) {
        byte bcd;

        if ((asc >= '0') && (asc <= '9'))
            bcd = (byte) (asc - '0');
        else if ((asc >= 'A') && (asc <= 'F'))
            bcd = (byte) (asc - 'A' + 10);
        else if ((asc >= 'a') && (asc <= 'f'))
            bcd = (byte) (asc - 'a' + 10);
        else
            bcd = (byte) (asc - 48);
        return bcd;
    }

    /**
     * BCD转字符串
     */
    private static String bcd2Str(byte[] bytes) {
        char temp[] = new char[bytes.length * 2], val;

        for (int i = 0; i < bytes.length; i++) {
            val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
            temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

            val = (char) (bytes[i] & 0x0f);
            temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
        }
        return new String(temp);
    }

    /**
     * 拆分字符串
     */
    private static String[] splitString(String string, int len) {
        int x = string.length() / len;
        int y = string.length() % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        String[] strings = new String[x + z];
        String str = "";
        for (int i = 0; i < x + z; i++) {
            if (i == x + z - 1 && y != 0) {
                str = string.substring(i * len, i * len + y);
            } else {
                str = string.substring(i * len, i * len + len);
            }
            strings[i] = str;
        }
        return strings;
    }

    /**
     * 拆分数组
     */
    private static byte[][] splitArray(byte[] data, int len) {
        int x = data.length / len;
        int y = data.length % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        byte[][] arrays = new byte[x + z][];
        byte[] arr;
        for (int i = 0; i < x + z; i++) {
            arr = new byte[len];
            if (i == x + z - 1 && y != 0) {
                System.arraycopy(data, i * len, arr, 0, y);
            } else {
                System.arraycopy(data, i * len, arr, 0, len);
            }
            arrays[i] = arr;
        }
        return arrays;
    }
}

JAVA - RSA实现

package com.dyhdyh.encrypt;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
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.Cipher;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

import sun.misc.BASE64Decoder;

/**
 * 用于java平台的RSA加密解密
 *
 * @desc
 * @author dengyuhan
 * @create 2016-3-31 下午2:36:18
 */
public class RSA {
    private static final String ALGORITHM = "RSA";
    private static final String TRANSFORMATION = "RSA";

    /**
     * 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 RSAPublicKey loadPublicKey(InputStream in) throws Exception {
        try {
            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 loadPublicKey(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
     * @return
     * @throws Exception
     *             加载公钥时产生的异常
     */
    public static RSAPublicKey loadPublicKey(String publicKeyStr)
            throws Exception {
        try {
            BASE64Decoder base64Decoder = new BASE64Decoder();
            byte[] buffer = base64Decoder.decodeBuffer(publicKeyStr);
            KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
            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 (IOException e) {
            throw new Exception("公钥数据内容读取错误");
        } catch (NullPointerException e) {
            throw new Exception("公钥数据为空");
        }
    }

    /**
     * 从文件中加载私钥
     *
     * @param in
     *            私钥输入流
     * @return
     * @throws Exception
     */
    public static RSAPrivateKey loadPrivateKey(InputStream in) throws Exception {
        try {
            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 loadPrivateKey(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");
        }
    }

    /**
     * 从字符串中加载私钥
     *
     * @desc
     * @param privateKeyStr
     *            私钥字符串
     * @return
     * @throws Exception
     */
    public static RSAPrivateKey loadPrivateKey(String privateKeyStr)
            throws Exception {
        try {
            BASE64Decoder base64Decoder = new BASE64Decoder();
            byte[] buffer = base64Decoder.decodeBuffer(privateKeyStr);
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
            KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
            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 (IOException e) {
            throw new Exception("私钥数据内容读取错误");
        } catch (NullPointerException e) {
            throw new Exception("私钥数据为空");
        }
    }

    /**
     * 公钥加密
     *
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static String encryptByPublicKey(String data, RSAPublicKey publicKey)
            throws Exception {
        // 模长
        int key_len = publicKey.getModulus().bitLength() / 8;
        // 加密数据长度 <= 模长-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
        // 如果明文长度大于模长-11则要分组加密
        for (String s : datas) {
            mi += bcd2Str(encryptByPublicKey(s.getBytes(), publicKey));
        }
        return mi;
    }

    /**
     * 公钥加密
     * @desc
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, RSAPublicKey publicKey)
            throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * 私钥加密
     * @desc
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data,
            RSAPrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 私钥加密
     * @desc
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static String encryptByPrivateKey(String data,
            RSAPrivateKey privateKey) throws Exception {
        // 模长
        int key_len = privateKey.getModulus().bitLength() / 8;
        // 加密数据长度 <= 模长-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
        // 如果明文长度大于模长-11则要分组加密
        for (String s : datas) {
            mi += bcd2Str(encryptByPrivateKey(s.getBytes(), privateKey));
        }
        return mi;
    }

    /**
     * 私钥解密
     *
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static String decryptByPrivateKey(String data,
            RSAPrivateKey privateKey) throws Exception {
        // 模长
        int key_len = privateKey.getModulus().bitLength() / 8;
        byte[] bytes = data.getBytes();
        byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
        // 如果密文长度大于模长则要分组解密
        String ming = "";
        byte[][] arrays = splitArray(bcd, key_len);
        for (byte[] arr : arrays) {
            ming += new String(decryptByPrivateKey(arr, privateKey));
        }
        return ming;
    }

    /**
     * 私钥解密
     * @desc
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] data,
            RSAPrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION,new BouncyCastleProvider());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 公钥解密
     * @desc
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static String decryptByPublicKey(String data,
            RSAPublicKey publicKey) throws Exception {
        // 模长
        int key_len = publicKey.getModulus().bitLength() / 8;
        byte[] bytes = data.getBytes();
        byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
        // 如果密文长度大于模长则要分组解密
        String ming = "";
        byte[][] arrays = splitArray(bcd, key_len);
        for (byte[] arr : arrays) {
            ming += new String(decryptByPublicKey(arr, publicKey));
        }
        return ming;
    }

    /**
     * 公钥解密
     * @desc
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data,
            RSAPublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION,new BouncyCastleProvider());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * ASCII码转BCD码
     *
     */
    private static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
        byte[] bcd = new byte[asc_len / 2];
        int j = 0;
        for (int i = 0; i < (asc_len + 1) / 2; i++) {
            bcd[i] = asc_to_bcd(ascii[j++]);
            bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
        }
        return bcd;
    }

    private static byte asc_to_bcd(byte asc) {
        byte bcd;

        if ((asc >= '0') && (asc <= '9'))
            bcd = (byte) (asc - '0');
        else if ((asc >= 'A') && (asc <= 'F'))
            bcd = (byte) (asc - 'A' + 10);
        else if ((asc >= 'a') && (asc <= 'f'))
            bcd = (byte) (asc - 'a' + 10);
        else
            bcd = (byte) (asc - 48);
        return bcd;
    }

    /**
     * BCD转字符串
     */
    private static String bcd2Str(byte[] bytes) {
        char temp[] = new char[bytes.length * 2], val;

        for (int i = 0; i < bytes.length; i++) {
            val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
            temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

            val = (char) (bytes[i] & 0x0f);
            temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
        }
        return new String(temp);
    }

    /**
     * 拆分字符串
     */
    private static String[] splitString(String string, int len) {
        int x = string.length() / len;
        int y = string.length() % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        String[] strings = new String[x + z];
        String str = "";
        for (int i = 0; i < x + z; i++) {
            if (i == x + z - 1 && y != 0) {
                str = string.substring(i * len, i * len + y);
            } else {
                str = string.substring(i * len, i * len + len);
            }
            strings[i] = str;
        }
        return strings;
    }

    /**
     * 拆分数组
     */
    private static byte[][] splitArray(byte[] data, int len) {
        int x = data.length / len;
        int y = data.length % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        byte[][] arrays = new byte[x + z][];
        byte[] arr;
        for (int i = 0; i < x + z; i++) {
            arr = new byte[len];
            if (i == x + z - 1 && y != 0) {
                System.arraycopy(data, i * len, arr, 0, y);
            } else {
                System.arraycopy(data, i * len, arr, 0, len);
            }
            arrays[i] = arr;
        }
        return arrays;
    }
}

JAVA的RSA跟Android的RSA有所不同：

1.加载key的时候，JAVA上用的是BASE64Decoder

BASE64Decoder base64Decoder = new BASE64Decoder();
byte[] buffer = base64Decoder.decodeBuffer(publicKeyStr);

而Android上用的Base64，这个地方只是API不一样，作用是一样的

byte[] buffer = Base64.decode(publicKeyStr, Base64.DEFAULT);

2.在JAVA平台上调用Cipher.getInstance()的时候，需要多传一个参数，也就是BouncyCastleProvider的实例：

Cipher cipher = Cipher.getInstance("RSA",new BouncyCastleProvider());

这个类jdk上是没有的，所以需要添加一个jar包bcprov-jdk15-143.jar

如果不这样做，JAVA上解密的时候就会抛出一个BadPaddingException

Exception in thread "main" javax.crypto.BadPaddingException: Blocktype mismatch: 0
    at sun.security.rsa.RSAPadding.unpadV15(RSAPadding.java:332)
    at sun.security.rsa.RSAPadding.unpad(RSAPadding.java:272)
    at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:356)
    at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:382)
    at javax.crypto.Cipher.doFinal(Cipher.java:2087)
    at com.dyhdyh.encrypt.RSA.decryptByPrivateKey(RSA.java:255)
    at com.dyhdyh.encrypt.RSA.decryptByPrivateKey(RSA.java:238)

这是因为Android的加密标准与JAVA的加密标准不一致导致，Android上的RSA实现是"RSA/None/NoPadding"，而标准JDK实现是"RSA/None/PKCS1Padding"，这造成了在Android上加密后无法在服务器上解密

最后来看看怎样混合加密(这里只举一种方式，附件里有完整的)

Android上加密

1.将openssl生成出来的公钥，放入assets文件夹内（不一定要放这里，只要能拿到文件内容就行）。

2.加载放在assets文件里的公钥

//加载RSA公钥
RSAPublicKey rsaPublicKey = RSA.loadPublicKey(getAssets().open("rsa_public_key.pem"));

3.再生成一个AES的密钥，用于AES加密

//生成一个AES密钥
String aesKey=AES.generateKeyString();

4.通过RSA的公钥来加密刚刚生成的AES密钥

//用RSA公钥加密AES的密钥
String encryptAesKey = RSA.encryptByPublicKey(aesKey, rsaPublicKey);

5.最后使用AES来加密需要传输的数据，AES加密需要传入两个参数，第一个是明文数据，第二个是3步生成出来的密钥

//再使用AES加密内容，传给服务器
String encryptContent = AES.encrypt(content, aesKey);

6.第5步返回的字符串就是加密过后的数据，最后将4和5传给服务端，接下来就是服务端的事情了。

客户端传过来密文之后，接下来就需要服务端来解密了

JAVA解密

1.加载RSA私钥(这里的私钥是跟客户端的公钥是成对的)

//加载私钥
RSAPrivateKey privateKey = RSA.loadPrivateKey(new FileInputStream("G:/RSA密钥/pkcs8_rsa_private_key.pem"));

2.通过RSA的私钥解密客户端传来的AES-KEY（也就是客户端的第4），因为这个key是加过密的，所以我们需要先将key解密成明文

//解密AES-KEY
String decryptAesKey = RSA.decryptByPrivateKey(aesKey, privateKey);

3.AES-KEY加密成明文之后，现在可以拿这个key来解密客户端传过来的数据了

//AES解密数据
String decrypt = AES.decrypt(content, decryptAesKey);

RSA-AES混合加密就是这个样子，有什么问题请跟帖回复，我会继续改进

最后附上完整demo

http://download.csdn.net/detail/aa464971/9478798