- 前言
- 环境搭建
- 创建Native代码
- 使用
前言
开发过程中，为了数据交互安全，决定对数据进行des加密，然后进行前后交互；但是，如果密钥放置在android代码里面，就算是混淆，反编译也很容易让人拿到密钥，数据加密的安全度不高，因此考虑通过jni来返回一个密钥对数据进行加解密。从而达到数据的安全性。
环境搭建
- 下载NDK
通过android studio去下载NDK插件；打开File–>Project Structure–>SDK Location–>Android NDK Location,如下图： - 如果是第一次，没有下载NDK插件，在红色箭头的地方有个按钮用于下载安装，点击等待下载即可，使用AS下载的NDK会默认反正你的sdk的目录路径下；亦或者选中蓝色剪头的按钮选择已经下载好的NDK;点击“OK”，配置成功之后，会在local.properties文件下看见相应的路径指向，如下图：
- 配置NDK环境变量
- 创建NDK_HOME
右键我的电脑–>属性–>高级系统设置–>环境变量–>系统变量–>新建–>创建一个“NDK_HOME”,NDK的路径就是上一步中配置的路径，如下图： - 添加path
在系统变量中找到Path–>编辑，将;%NDK_HOME%添加至path中，如下图： - 验证配置是否成功
在cmd下输入“ndk-build”指令，如果出现下图结果，即配置成功：
创建Native代码
- 在java目录下创建一个带有native方法的java文件
/**
* native
*/
public class SmartCardJniUtil {
/**
* 加载so库
*/
static {
System.loadLibrary("SCJniUtil");
}
/**
* 获取密钥
* @return 密钥
*/
public native String getKey();
}- 通过Build–>Make Project项目
成功之后，在app–>intermediates–>classes–>debug–>个人项目路径下找到上面新建的native类的class文件，如下图： - 生成头文件
- 在File—settings—plugins下勾选Termainal
- 指令生成头文件
javah -d jni -classpath ;….\build\intermediates\classes\debug 类的包名。
按着以上说明，首先通过cd app\src\main跳转到main目录下，然后输入如下指令：
javah -d jni -classpath E:**\sdk\platforms\android-20\android.jar;….\build\intermediates\classes\debug com.a.b.c.SmartCardJniUtil
如下图： - 成功之后会在main目录下多一个jni文件，并包含了一个.h的头文件，如下图：
- 创建.c文件
在jni目录下右键–>New–>C/C++ Source File创建一个SmartCardJniUtil.c文件，然后引入头文件，返回密钥，如下代码：
#include "com_a_b_c_SmartCardJniUtil.h"
JNIEXPORT jstring JNICALL Java_com_a_b_c_SmartCardJniUtil_getKey
(JNIEnv *env, jobject jobject1) {
return (*env)->NewStringUTF(env, "1122334455667788");
};- 在build.gradle文件下添加配置，代码如下：
buildTypes {
release {
minifyEnabled true
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
ndk {
moduleName "SCJniUtil" //生成的so名字
abiFilters "armeabi", "armeabi-v7a", "x86" //输出指定三种abi体系结构下的so库。
}
}
debug {
ndk {
moduleName "SCJniUtil" //生成的so名字
abiFilters "armeabi", "armeabi-v7a", "x86" //输出指定三种abi体系结构下的so库。
}
}
}
sourceSets {
main {
jniLibs.srcDirs = ['libs']
}
}- 清理并重新make项目，生成so库，如下图：
- 关于Android.mk文件说明
通过eclipse开发jni的时候，需要进行一个Android.mk文件的配置，但是Android Studio中并没有做，没有做不代表没有，AS自动帮我们生成了，不需要我们自己去创建并配置，如下图： - 混淆文件中添加不混淆native的配置
-keepclasseswithmembernames class * {
native <methods>;
}使用
- 通过jni获取密钥
当以上步骤完成之后，实例化native对象，调用相应的方法即可获取到相应的结果，代码如下：
//实例化对象
SmartCardJniUtil jniUtil = new SmartCardJniUtil();
//获取密钥
jniUtil.getKey()- des加解密工具
public class DesUtil {
/**
* 数据加密，算法（DES）
*
* @param data 要进行加密的数据
* @return 加密后的数据
*/
public static String encryptBasedDes(String data, String keyStr) {
keyStr = StringUtilsSimple.leftPad(keyStr, 16, "0");
byte[] DES_KEY = ByteUtil.hexStr2Byte(keyStr);
String encryptedData = null;
try {
// DES算法要求有一个可信任的随机数源
SecureRandom sr = new SecureRandom();
DESKeySpec deskey = new DESKeySpec(DES_KEY);
// 创建一个密匙工厂，然后用它把DESKeySpec转换成一个SecretKey对象
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey key = keyFactory.generateSecret(deskey);
// 加密对象
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, key, sr);
// 加密，并把字节数组编码成字符串
encryptedData = ByteUtil.hexToStr(cipher.doFinal(data.getBytes()));
} catch (Exception e) {
// log.error("加密错误，错误信息：", e);
throw new RuntimeException("加密错误，错误信息：", e);
}
return encryptedData;
}
/**
* 数据解密，算法（DES）
*
* @param cryptData 加密数据
* @return 解密后的数据
*/
public static String decryptBasedDes(String cryptData, String keyStr) {
keyStr = StringUtilsSimple.leftPad(keyStr, 16, "0");
byte[] DES_KEY = ByteUtil.hexStr2Byte(keyStr);
String decryptedData = null;
try {
// DES算法要求有一个可信任的随机数源
SecureRandom sr = new SecureRandom();
DESKeySpec deskey = new DESKeySpec(DES_KEY);
// 创建一个密匙工厂，然后用它把DESKeySpec转换成一个SecretKey对象
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey key = keyFactory.generateSecret(deskey);
// 解密对象
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.DECRYPT_MODE, key, sr);
// 把字符串解码为字节数组，并解密
decryptedData = new String(cipher.doFinal(ByteUtil.hexStr2Byte(cryptData)));
} catch (Exception e) {
// log.error("解密错误，错误信息：", e);
throw new RuntimeException("解密错误，错误信息：", e);
}
return decryptedData;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
String str = "123456789";
// DES数据加密
long time = System.currentTimeMillis();
String s1 = encryptBasedDes(str, "1122334411223344");
System.out.println("time1:" + (System.currentTimeMillis() - time));
System.out.println(s1);
// DES数据解密
long time2 = System.currentTimeMillis();
String s2 = decryptBasedDes(s1, "1122334411223344");
System.out.println("time2:" + (System.currentTimeMillis() - time2));
System.err.println(s2);
}
}- 文本左右补位的工具
public class StringUtilsSimple
{
/**
* A String for a space character.
*
* @since 3.2
*/
public static final String SPACE = " ";
/**
* <p>The maximum size to which the padding constant(s) can expand.</p>
*/
private static final int PAD_LIMIT = 8192;
// Empty checks
// -----------------------------------------------------------------------
/**
* <p>
* Checks if a CharSequence is empty ("") or null.
* </p>
*
* <pre>
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
* </pre>
*
* <p>
* NOTE: This method changed in Lang version 2.0. It no longer trims the
* CharSequence. That functionality is available in isBlank().
* </p>
*
* @param cs
* the CharSequence to check, may be null
* @return {@code true} if the CharSequence is empty or null
* @since 3.0 Changed signature from isEmpty(String) to
* isEmpty(CharSequence)
*/
public static boolean isEmpty(final CharSequence cs)
{
return cs == null || cs.length() == 0;
}
/**
* <p>
* Left pad a String with a specified String.
* </p>
*
* <p>
* Pad to a size of {@code size}.
* </p>
*
* <pre>
* StringUtils.leftPad(null, *, *) = null
* StringUtils.leftPad("", 3, "z") = "zzz"
* StringUtils.leftPad("bat", 3, "yz") = "bat"
* StringUtils.leftPad("bat", 5, "yz") = "yzbat"
* StringUtils.leftPad("bat", 8, "yz") = "yzyzybat"
* StringUtils.leftPad("bat", 1, "yz") = "bat"
* StringUtils.leftPad("bat", -1, "yz") = "bat"
* StringUtils.leftPad("bat", 5, null) = " bat"
* StringUtils.leftPad("bat", 5, "") = " bat"
* </pre>
*
* @param str
* the String to pad out, may be null
* @param size
* the size to pad to
* @param padStr
* the String to pad with, null or empty treated as single space
* @return left padded String or original String if no padding is necessary,
* {@code null} if null String input
*/
public static String leftPad(final String str, final int size, String padStr)
{
if (str == null)
{
return null;
}
if (isEmpty(padStr))
{
padStr = SPACE;
}
final int padLen = padStr.length();
final int strLen = str.length();
final int pads = size - strLen;
if (pads <= 0)
{
return str; // returns original String when possible
}
if (padLen == 1 && pads <= PAD_LIMIT)
{
return leftPad(str, size, padStr.charAt(0));
}
if (pads == padLen)
{
return padStr.concat(str);
}
else if (pads < padLen)
{
return padStr.substring(0, pads).concat(str);
}
else
{
final char[] padding = new char[pads];
final char[] padChars = padStr.toCharArray();
for (int i = 0; i < pads; i++)
{
padding[i] = padChars[i % padLen];
}
return new String(padding).concat(str);
}
}
/**
* <p>Left pad a String with a specified character.</p>
*
* <p>Pad to a size of {@code size}.</p>
*
* <pre>
* StringUtils.leftPad(null, *, *) = null
* StringUtils.leftPad("", 3, 'z') = "zzz"
* StringUtils.leftPad("bat", 3, 'z') = "bat"
* StringUtils.leftPad("bat", 5, 'z') = "zzbat"
* StringUtils.leftPad("bat", 1, 'z') = "bat"
* StringUtils.leftPad("bat", -1, 'z') = "bat"
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padChar the character to pad with
* @return left padded String or original String if no padding is necessary,
* {@code null} if null String input
* @since 2.0
*/
public static String leftPad(final String str, final int size, final char padChar) {
if (str == null) {
return null;
}
final int pads = size - str.length();
if (pads <= 0) {
return str; // returns original String when possible
}
if (pads > PAD_LIMIT) {
return leftPad(str, size, String.valueOf(padChar));
}
return repeat(padChar, pads).concat(str);
}
/**
* <p>Returns padding using the specified delimiter repeated
* to a given length.</p>
*
* <pre>
* StringUtils.repeat('e', 0) = ""
* StringUtils.repeat('e', 3) = "eee"
* StringUtils.repeat('e', -2) = ""
* </pre>
*
* <p>Note: this method doesn't not support padding with
* <a href="http://www.unicode.org/glossary/#supplementary_character">Unicode Supplementary Characters</a>
* as they require a pair of {@code char}s to be represented.
* If you are needing to support full I18N of your applications
* consider using {@link #repeat(String, int)} instead.
* </p>
*
* @param ch character to repeat
* @param repeat number of times to repeat char, negative treated as zero
* @return String with repeated character
* @see #repeat(String, int)
*/
public static String repeat(final char ch, final int repeat) {
final char[] buf = new char[repeat];
for (int i = repeat - 1; i >= 0; i--) {
buf[i] = ch;
}
return new String(buf);
}
/**
* <p>Right pad a String with a specified String.</p>
*
* <p>The String is padded to the size of {@code size}.</p>
*
* <pre>
* StringUtils.rightPad(null, *, *) = null
* StringUtils.rightPad("", 3, "z") = "zzz"
* StringUtils.rightPad("bat", 3, "yz") = "bat"
* StringUtils.rightPad("bat", 5, "yz") = "batyz"
* StringUtils.rightPad("bat", 8, "yz") = "batyzyzy"
* StringUtils.rightPad("bat", 1, "yz") = "bat"
* StringUtils.rightPad("bat", -1, "yz") = "bat"
* StringUtils.rightPad("bat", 5, null) = "bat "
* StringUtils.rightPad("bat", 5, "") = "bat "
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padStr the String to pad with, null or empty treated as single space
* @return right padded String or original String if no padding is necessary,
* {@code null} if null String input
*/
public static String rightPad(final String str, final int size, String padStr) {
if (str == null) {
return null;
}
if (isEmpty(padStr)) {
padStr = SPACE;
}
final int padLen = padStr.length();
final int strLen = str.length();
final int pads = size - strLen;
if (pads <= 0) {
return str; // returns original String when possible
}
if (padLen == 1 && pads <= PAD_LIMIT) {
return rightPad(str, size, padStr.charAt(0));
}
if (pads == padLen) {
return str.concat(padStr);
} else if (pads < padLen) {
return str.concat(padStr.substring(0, pads));
} else {
final char[] padding = new char[pads];
final char[] padChars = padStr.toCharArray();
for (int i = 0; i < pads; i++) {
padding[i] = padChars[i % padLen];
}
return str.concat(new String(padding));
}
}
/**
* <p>Right pad a String with a specified character.</p>
*
* <p>The String is padded to the size of {@code size}.</p>
*
* <pre>
* StringUtils.rightPad(null, *, *) = null
* StringUtils.rightPad("", 3, 'z') = "zzz"
* StringUtils.rightPad("bat", 3, 'z') = "bat"
* StringUtils.rightPad("bat", 5, 'z') = "batzz"
* StringUtils.rightPad("bat", 1, 'z') = "bat"
* StringUtils.rightPad("bat", -1, 'z') = "bat"
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padChar the character to pad with
* @return right padded String or original String if no padding is necessary,
* {@code null} if null String input
* @since 2.0
*/
public static String rightPad(final String str, final int size, final char padChar) {
if (str == null) {
return null;
}
final int pads = size - str.length();
if (pads <= 0) {
return str; // returns original String when possible
}
if (pads > PAD_LIMIT) {
return rightPad(str, size, String.valueOf(padChar));
}
return str.concat(repeat(padChar, pads));
}
}
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