Add support for client-side encryption

[braintree]

Add support for client-side encryption

[michaelfairley]

We actually have an Android client-side encryption library that might serve your purposes. Despite having Android in the name, it doesn't actually have dependencies on any Android libraries, so it should hopefully work in any Java project. That said, because it was designed for Android, it's not distributed from Maven Central or anything, so you might need to include our source files in your project.

[willglynn]

Seems to work. Thanks! The availability of the Android client in a normal JVM context somehow did not occur to me.

The easiest way for me to integrate this was to define a local maven repo:

<repositories>
    <repository>
        <id>local-maven-repo</id>
        <url>file://${basedir}/../local-maven-repo</url>
    </repository>
</repositories>
…
<dependencies>
    <dependency>
        <groupId>braintree</groupId>
        <artifactId>braintree-android-encryption</artifactId>
        <version>1.0.0</version>
    </dependency>
</dependencies>

And then populate it with:

$ wget https://www.braintreepayments.com/assets/client_libraries/android/braintree-android-encryption-1.0.0.jar
$ mkdir -p ../local-maven-repo/braintree/braintree-android-encryption/1.0.0
$ mv braintree-android-encryption-1.0.0.jar ../local-maven-repo/braintree/braintree-android-encryption/1.0.0

Not quite as convenient as Maven Central, but not especially painful either.