![]() Using Collection. To demonstrate this approach, our app includes JNI calls to a C custom function that XORs our keys just like we did in our Java-based implementation. For our first solution, well remove stopwords manually by iterating over each word and checking if its a stopword: 4. It certainly is one of the more effective strategies to thwart reverse engineering attempts since it adds several layers of complexity. The strategy of moving sensitive operations out of Java and into native libraries was a common mitigation suggested in the /r/androiddev discussion. While I won’t try to cover all of the nuances of patching binaries here, rest assured that after patching our app with the new logging statement, every key that passes through this method will be dutifully written out to the console, negating all of our hard work. Instead of trying to figure out what permutations we take along the way, we can simply modify the generated instructions to log the values out to the console at the end. Public void useXorStringHiding ( String myHiddenMessage ), Lcom/apothesource/hidingpasswords/ HidingUtil -> a ( [B[BZ ) V We’ve done just that as well in our res/values/strings.xml file: Including Secrets in strings.xmlĪs an Android developer, your first instinct is probably to include any secrets, such as an API key, in your XML resources as you would with any other assets. It’s important that you appreciate the perspective of both the developer and the reverse-engineer as you look for potential vulnerabilities. The full source code is available for review, but be sure to also take a look at the decompiled source. ![]() I found the documentation for Java EE 7, can't find anything newer. To help illustrate some of these concepts, I created an example Android app on Github that we’ll analyze in this post. \\begingroup\ Looks like there's a class that may do the email parsing you want (ie can return just the front). You can also use the same annotation at the field level. You can ignore null fields at the class level by using JsonInclude (Include.NONNULL) to only include non-null fields, thus excluding any attribute whose value is null. While not a comprehensive review, we’ll take a look at the most common secret-stashing strategies (and how it can go wrong): In order to better control JSON output, you can ignore null fields, and Jackson provides a couple of options to do that. I would encrypt the string in a txt file and heavily obfuscate the key in your code. ![]() As a follow up on my somewhat incoherent rant about developers hiding passwords, keys, and other sensitive information in Android apps, I wanted to go through a semi-realistic example and explain the thought behind some of these strategies and why they may not be as effective as you might initially hope.
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