在项目工程中,有时候需要对网络传输的数据进行加密。有多种方式,本文使用3DES与RSA加密结合使用。

基本流程如下:

1、假设客户端获取了用户名与密码,需要传给服务器;本文使用RSA工具类生成公钥月私钥,公钥用于客户端加密,私钥用于服务端解密。 

 String content="用户名+密码";

2、自定义3DES加密密钥和向量:

 // 密钥 ,至少24位
    private final static String secretKey = "123456781234567812345678aaa";
    // 向量 8位
    private final static String iv = "3213abcd";

3、使用3DES对内容加密获取加密后的字符串

4、使用RSA对密钥和向量用公钥加密

5、服务器接收数据,用RSA私钥解密,获取密钥和向量,再使用3DES解密获取内容。

原理是:使用3DES对长内容加密,使用RSA对3DES使用的密钥加密,这样加密速度快,效率高。

注意点:

String。getBytes的方式,必须用特定的工具。这里本文使用的是系统自带的Base64中的方法。也可以使用sun中的BASE64Encoder方式,但是这种需要下载专门的jar。 

         RSA加密速度较慢,所以我们不对长内容加密。假设有变态的非要对长长的内容加密,本文在下面的RSA工具类中也封装了相关的方法,partSplit分段加密和解密。

具体代码如下:

3DES加密解密方法及常量:


// 密钥 ,至少24位
private final static String secretKey = "123456781234567812345678aaa";
// 向量 8位
private final static String iv = "3213abcd";
// 加解密统一使用的编码方式
private final static String encoding = "utf-8";


/**
 * DESTool加密
 *
 * @param plainText 普通文本
 * @return
 * @throws Exception
 */
public static String encode(String plainText) throws Exception {
    Key deskey = null;
    DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
    SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("DESede");
    deskey = keyfactory.generateSecret(spec);

    Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
    IvParameterSpec ips = new IvParameterSpec(iv.getBytes());
    cipher.init(Cipher.ENCRYPT_MODE, deskey, ips);
    byte[] encryptData = cipher.doFinal(plainText.getBytes(encoding));
    return Base64.encodeToString(encryptData,Base64.DEFAULT);
}

/**
 * DESTool解密
 *
 * @param encryptText 加密文本
 * @return
 * @throws Exception
 */
public static String decode(String encryptText, String secretKey, String iv) throws Exception {
    Key deskey = null;
    DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
    SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("desede");
    deskey = keyfactory.generateSecret(spec);
    Cipher cipher = Cipher.getInstance("desede/CBC/PKCS5Padding");
    IvParameterSpec ips = new IvParameterSpec(iv.getBytes());
    cipher.init(Cipher.DECRYPT_MODE, deskey, ips);
    byte[] decryptData = cipher.doFinal(Base64.decode(encryptText,Base64.DEFAULT));
    return new String(decryptData, encoding);
}

主要测试代码:


b31.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        try {
            String content="用户名+密码";
            Log.e("b31", "加密前content数据 ---->" + content);
            String s1 = encode(content);
            Log.e("b31", "DES加密后content数据 ---->" + s1);

            KeyPair keyPair = RSAUtil.generateRSAKeyPair(RSAUtil.DEFAULT_KEY_SIZE);
            // 公钥
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
            // 私钥
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

            byte[] s2 = RSAUtil.encryptByPublicKey(secretKey.getBytes(), publicKey.getEncoded());
            String s21 = Base64.encodeToString(s2,Base64.DEFAULT);
            Log.e("b31", "公钥加密后的 secretKey---->" + s21);
            byte[] s3 = RSAUtil.encryptByPublicKey(iv.getBytes(), publicKey.getEncoded());
            String s31 = Base64.encodeToString(s3,Base64.DEFAULT);
            Log.e("b31", "公钥加密后的 iv---->" + s31);

            //服务器端私钥解密,DES解密;s1,s21 s31为网络传输的参数:内容,加密key,加密向量
            byte[] s21bytes = Base64.decode(s21,Base64.DEFAULT);
            byte[] s31bytes = Base64.decode(s31,Base64.DEFAULT);
            byte[] s4 = RSAUtil.decryptByPrivateKey(s21bytes, privateKey.getEncoded());
            String s41 = new String(s4);
            Log.e("b31", "私钥解密后的 secretKey---->" + s41);
            byte[] s5 = RSAUtil.decryptByPrivateKey(s31bytes, privateKey.getEncoded());
            String s51 = new String(s5);
            Log.e("b31", "私钥解密后的 iv---->" + s51);
            if (secretKey.equals(s41) && iv.equals(s51)) {
                String s6 = decode(s1, s41, s51);
                Log.e("b31", "DES解密后的 content---->" + s6);
            } else {
                Log.e("b31", "参数不一致---->");
            }


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

RSA加密解密工具类:


public class RSAUtil {
    public static final String RSA = "RSA";// 非对称加密密钥算法
    public static final String ECB_PKCS1_PADDING = "RSA/ECB/PKCS1Padding";//加密填充方式
    public static final int DEFAULT_KEY_SIZE = 2048;//秘钥默认长度
    public static final byte[] DEFAULT_SPLIT = "#PART#".getBytes();    // 当要加密的内容超过bufferSize,则采用partSplit进行分块加密
    public static final int DEFAULT_BUFFERSIZE = (DEFAULT_KEY_SIZE / 8) - 11;// 当前秘钥支持加密的最大字节数

    /**
     * 随机生成RSA密钥对
     *
     * @param keyLength 密钥长度,范围:512~2048
     *                  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;
        }
    }

    /**
     * 用公钥对字符串进行加密
     *
     * @param data 原文
     */
    public static byte[] encryptByPublicKey(byte[] data, byte[] publicKey) throws Exception {
        // 得到公钥
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKey);
        KeyFactory kf = KeyFactory.getInstance(RSA);
        PublicKey keyPublic = kf.generatePublic(keySpec);
        // 加密数据
        Cipher cp = Cipher.getInstance(ECB_PKCS1_PADDING);
        cp.init(Cipher.ENCRYPT_MODE, keyPublic);
        return cp.doFinal(data);
    }
    /**
     * 私钥加密
     *
     * @param data       待加密数据
     * @param privateKey 密钥
     * @return byte[] 加密数据
     */
    public static byte[] encryptByPrivateKey(byte[] data, byte[] privateKey) throws Exception {
        // 得到私钥
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKey);
        KeyFactory kf = KeyFactory.getInstance(RSA);
        PrivateKey keyPrivate = kf.generatePrivate(keySpec);
        // 数据加密
        Cipher cipher = Cipher.getInstance(ECB_PKCS1_PADDING);
        cipher.init(Cipher.ENCRYPT_MODE, keyPrivate);
        return cipher.doFinal(data);
    }
    /**
     * 公钥解密
     *
     * @param data      待解密数据
     * @param publicKey 密钥
     * @return byte[] 解密数据
     */
    public static byte[] decryptByPublicKey(byte[] data, byte[] publicKey) throws Exception {
        // 得到公钥
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKey);
        KeyFactory kf = KeyFactory.getInstance(RSA);
        PublicKey keyPublic = kf.generatePublic(keySpec);
        // 数据解密
        Cipher cipher = Cipher.getInstance(ECB_PKCS1_PADDING);
        cipher.init(Cipher.DECRYPT_MODE, keyPublic);
        return cipher.doFinal(data);
    }
    /**
     * 使用私钥进行解密
     */
    public static byte[] decryptByPrivateKey(byte[] encrypted, byte[] privateKey) throws Exception {
        // 得到私钥
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKey);
        KeyFactory kf = KeyFactory.getInstance(RSA);
        PrivateKey keyPrivate = kf.generatePrivate(keySpec);

        // 解密数据
        Cipher cp = Cipher.getInstance(ECB_PKCS1_PADDING);
        cp.init(Cipher.DECRYPT_MODE, keyPrivate);
        byte[] arr = cp.doFinal(encrypted);
        return arr;
    }

    /**
     * 用公钥对字符串进行分段加密
     *
     */
    public static byte[] encryptByPublicKeyForSpilt(byte[] data, byte[] publicKey) throws Exception {
        int dataLen = data.length;
        if (dataLen <= DEFAULT_BUFFERSIZE) {
            return encryptByPublicKey(data, publicKey);
        }
        List<Byte> allBytes = new ArrayList<Byte>(2048);
        int bufIndex = 0;
        int subDataLoop = 0;
        byte[] buf = new byte[DEFAULT_BUFFERSIZE];
        for (int i = 0; i < dataLen; i++) {
            buf[bufIndex] = data[i];
            if (++bufIndex == DEFAULT_BUFFERSIZE || i == dataLen - 1) {
                subDataLoop++;
                if (subDataLoop != 1) {
                    for (byte b : DEFAULT_SPLIT) {
                        allBytes.add(b);
                    }
                }
                byte[] encryptBytes = encryptByPublicKey(buf, publicKey);
                for (byte b : encryptBytes) {
                    allBytes.add(b);
                }
                bufIndex = 0;
                if (i == dataLen - 1) {
                    buf = null;
                } else {
                    buf = new byte[Math.min(DEFAULT_BUFFERSIZE, dataLen - i - 1)];
                }
            }
        }
        byte[] bytes = new byte[allBytes.size()];
        {
            int i = 0;
            for (Byte b : allBytes) {
                bytes[i++] = b.byteValue();
            }
        }
        return bytes;
    }

    /**
     * 分段加密
     *
     * @param data       要加密的原始数据
     * @param privateKey 秘钥
     */
    public static byte[] encryptByPrivateKeyForSpilt(byte[] data, byte[] privateKey) throws Exception {
        int dataLen = data.length;
        if (dataLen <= DEFAULT_BUFFERSIZE) {
            return encryptByPrivateKey(data, privateKey);
        }
        List<Byte> allBytes = new ArrayList<Byte>(2048);
        int bufIndex = 0;
        int subDataLoop = 0;
        byte[] buf = new byte[DEFAULT_BUFFERSIZE];
        for (int i = 0; i < dataLen; i++) {
            buf[bufIndex] = data[i];
            if (++bufIndex == DEFAULT_BUFFERSIZE || i == dataLen - 1) {
                subDataLoop++;
                if (subDataLoop != 1) {
                    for (byte b : DEFAULT_SPLIT) {
                        allBytes.add(b);
                    }
                }
                byte[] encryptBytes = encryptByPrivateKey(buf, privateKey);
                for (byte b : encryptBytes) {
                    allBytes.add(b);
                }
                bufIndex = 0;
                if (i == dataLen - 1) {
                    buf = null;
                } else {
                    buf = new byte[Math.min(DEFAULT_BUFFERSIZE, dataLen - i - 1)];
                }
            }
        }
        byte[] bytes = new byte[allBytes.size()];
        {
            int i = 0;
            for (Byte b : allBytes) {
                bytes[i++] = b.byteValue();
            }
        }
        return bytes;
    }

    /**
     * 公钥分段解密
     *
     * @param encrypted 待解密数据
     * @param publicKey 密钥
     */
    public static byte[] decryptByPublicKeyForSpilt(byte[] encrypted, byte[] publicKey) throws Exception {
        int splitLen = DEFAULT_SPLIT.length;
        if (splitLen <= 0) {
            return decryptByPublicKey(encrypted, publicKey);
        }
        int dataLen = encrypted.length;
        List<Byte> allBytes = new ArrayList<Byte>(1024);
        int latestStartIndex = 0;
        for (int i = 0; i < dataLen; i++) {
            byte bt = encrypted[i];
            boolean isMatchSplit = false;
            if (i == dataLen - 1) {
                // 到data的最后了
                byte[] part = new byte[dataLen - latestStartIndex];
                System.arraycopy(encrypted, latestStartIndex, part, 0, part.length);
                byte[] decryptPart = decryptByPublicKey(part, publicKey);
                for (byte b : decryptPart) {
                    allBytes.add(b);
                }
                latestStartIndex = i + splitLen;
                i = latestStartIndex - 1;
            } else if (bt == DEFAULT_SPLIT[0]) {
                // 这个是以split[0]开头
                if (splitLen > 1) {
                    if (i + splitLen < dataLen) {
                        // 没有超出data的范围
                        for (int j = 1; j < splitLen; j++) {
                            if (DEFAULT_SPLIT[j] != encrypted[i + j]) {
                                break;
                            }
                            if (j == splitLen - 1) {
                                // 验证到split的最后一位,都没有break,则表明已经确认是split段
                                isMatchSplit = true;
                            }
                        }
                    }
                } else {
                    // split只有一位,则已经匹配了
                    isMatchSplit = true;
                }
            }
            if (isMatchSplit) {
                byte[] part = new byte[i - latestStartIndex];
                System.arraycopy(encrypted, latestStartIndex, part, 0, part.length);
                byte[] decryptPart = decryptByPublicKey(part, publicKey);
                for (byte b : decryptPart) {
                    allBytes.add(b);
                }
                latestStartIndex = i + splitLen;
                i = latestStartIndex - 1;
            }
        }
        byte[] bytes = new byte[allBytes.size()];
        {
            int i = 0;
            for (Byte b : allBytes) {
                bytes[i++] = b.byteValue();
            }
        }
        return bytes;
    }

    /**
     * 使用私钥分段解密
     *
     */
    public static byte[] decryptByPrivateKeyForSpilt(byte[] encrypted, byte[] privateKey) throws Exception {
        int splitLen = DEFAULT_SPLIT.length;
        if (splitLen <= 0) {
            return decryptByPrivateKey(encrypted, privateKey);
        }
        int dataLen = encrypted.length;
        List<Byte> allBytes = new ArrayList<Byte>(1024);
        int latestStartIndex = 0;
        for (int i = 0; i < dataLen; i++) {
            byte bt = encrypted[i];
            boolean isMatchSplit = false;
            if (i == dataLen - 1) {
                // 到data的最后了
                byte[] part = new byte[dataLen - latestStartIndex];
                System.arraycopy(encrypted, latestStartIndex, part, 0, part.length);
                byte[] decryptPart = decryptByPrivateKey(part, privateKey);
                for (byte b : decryptPart) {
                    allBytes.add(b);
                }
                latestStartIndex = i + splitLen;
                i = latestStartIndex - 1;
            } else if (bt == DEFAULT_SPLIT[0]) {
                // 这个是以split[0]开头
                if (splitLen > 1) {
                    if (i + splitLen < dataLen) {
                        // 没有超出data的范围
                        for (int j = 1; j < splitLen; j++) {
                            if (DEFAULT_SPLIT[j] != encrypted[i + j]) {
                                break;
                            }
                            if (j == splitLen - 1) {
                                // 验证到split的最后一位,都没有break,则表明已经确认是split段
                                isMatchSplit = true;
                            }
                        }
                    }
                } else {
                    // split只有一位,则已经匹配了
                    isMatchSplit = true;
                }
            }
            if (isMatchSplit) {
                byte[] part = new byte[i - latestStartIndex];
                System.arraycopy(encrypted, latestStartIndex, part, 0, part.length);
                byte[] decryptPart = decryptByPrivateKey(part, privateKey);
                for (byte b : decryptPart) {
                    allBytes.add(b);
                }
                latestStartIndex = i + splitLen;
                i = latestStartIndex - 1;
            }
        }
        byte[] bytes = new byte[allBytes.size()];
        {
            int i = 0;
            for (Byte b : allBytes) {
                bytes[i++] = b.byteValue();
            }
        }
        return bytes;
    }
}