Most app developers will integrate some third party libraries into their apps. If it's to access a service, such as Dropbox or YouTube, or for logging crashes. The number of third party libraries and services is staggering. Most of those libraries and services are integrated by somehow authenticating with the service, most of the time, this happens through an API key. For security purposes, services usually generate a public and private, often also referred to as secret, key. Unfortunately, in order to connect to the services, this private key must be used to authenticate and hence, probably be part of the application.
Needless to say, that this faces in immense security problem. Public and private API keys can be extracted from APKs in a matter of minutes and can easily be automated.
假设我有类似的东西，我如何保护密钥:
public class DropboxService {
private final static String APP_KEY = "jk433g34hg3";
private final static String APP_SECRET = "987dwdqwdqw90";
private final static AccessType ACCESS_TYPE = AccessType.DROPBOX;
// SOME MORE CODE HERE
}
你认为储存私钥的最佳及最安全的方法是什么?混淆，加密，你怎么看?
另一种方法是一开始就不要在设备上保存秘密!请参阅移动API安全技术(特别是第3部分)。
使用历史悠久的间接传统，分享API端点和应用程序身份验证服务之间的秘密。
当您的客户端想要进行API调用时，它要求应用程序认证服务对其进行身份验证(使用强大的远程认证技术)，并接收由秘密签名的时间限制令牌(通常是JWT)。
令牌随每个API调用一起发送，端点可以在对请求执行之前验证其签名。
真正的秘密永远不会出现在设备上;事实上，应用程序从来不知道它是否有效，它只是请求身份验证并传递结果令牌。间接的好处是，如果你想改变秘密，你可以不需要用户更新他们安装的应用程序。
所以如果你想保护你的秘密，从一开始就不要把它放在你的应用程序中是一个很好的方法。
很少有想法，在我看来，只有第一个想法给了一些保证:
Keep your secrets on some server on internet, and when needed just grab them and use. If user is about to use dropbox then nothing stops you from making request to your site and get your secret key.
Put your secrets in jni code, add some variable code to make your libraries bigger and more difficult to decompile. You might also split key string in few parts and keep them in various places.
use obfuscator, also put in code hashed secret and later on unhash it when needed to use.
Put your secret key as last pixels of one of your image in assets. Then when needed read it in your code. Obfuscating your code should help hide code that will read it.
如果你想快速看看阅读你的apk代码是多么容易，然后获取APKAnalyser:
http://developer.sonymobile.com/knowledge-base/tool-guides/analyse-your-apks-with-apkanalyser/
As it is, your compiled application contains the key strings, but also the constant names APP_KEY and APP_SECRET. Extracting keys from such self-documenting code is trivial, for instance with the standard Android tool dx.
You can apply ProGuard. It will leave the key strings untouched, but it will remove the constant names. It will also rename classes and methods with short, meaningless names, where ever possible. Extracting the keys then takes some more time, for figuring out which string serves which purpose.
Note that setting up ProGuard shouldn't be as difficult as you fear. To begin with, you only need to enable ProGuard, as documented in project.properties. If there are any problems with third-party libraries, you may need to suppress some warnings and/or prevent them from being obfuscated, in proguard-project.txt. For instance:
-dontwarn com.dropbox.**
-keep class com.dropbox.** { *; }
This is a brute-force approach; you can refine such configuration once the processed application works.
You can obfuscate the strings manually in your code, for instance with a Base64 encoding or preferably with something more complicated; maybe even native code. A hacker will then have to statically reverse-engineer your encoding or dynamically intercept the decoding in the proper place.
You can apply a commercial obfuscator, like ProGuard's specialized sibling DexGuard. It can additionally encrypt/obfuscate the strings and classes for you. Extracting the keys then takes even more time and expertise.
You might be able to run parts of your application on your own server. If you can keep the keys there, they are safe.
In the end, it's an economic trade-off that you have to make: how important are the keys, how much time or software can you afford, how sophisticated are the hackers who are interested in the keys, how much time will they want to spend, how much worth is a delay before the keys are hacked, on what scale will any successful hackers distribute the keys, etc. Small pieces of information like keys are more difficult to protect than entire applications. Intrinsically, nothing on the client-side is unbreakable, but you can certainly raise the bar.
(我是ProGuard和DexGuard的开发者)
