Dracoon Java Crypto SDK

A library which implements the client-side encryption of Dracoon.

Introduction

A document which describes the client-side encryption in detail can be found here:

https://support.dracoon.com/hc/en-us/articles/360000986345

Setup

Minimum Requirements

Java 8 or newer

Download

Maven: Add this dependency to your pom.xml:

<dependency>
    <groupId>com.dracoon</groupId>
    <artifactId>dracoon-crypto-sdk</artifactId>
    <version>3.0.1</version>
</dependency>

Gradle: Add this dependency to your build.gradle:

compile 'com.dracoon:dracoon-crypto-sdk:3.0.1'

JAR import: The latest JAR can be found here.

Note that you also need to include the following dependencies:

1. Bouncy Castle PKIX/CMS/...: https://mvnrepository.com/artifact/org.bouncycastle/bcpkix-jdk18on:1.78.1
2. Bouncy Castle Provider: https://mvnrepository.com/artifact/org.bouncycastle/bcprov-jdk18on:1.78.1
3. Bouncy Castle Utils: https://mvnrepository.com/artifact/org.bouncycastle/bcutil-jdk18on:1.78.1

Java JCE Setup

IMPORTANT FOR JAVA VERSION 8 (<162):

You need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. Otherwise you'll get an exception about key length or an exception when parsing PKCS private keys.

The Unlimited Strength Jurisdiction Policy File can be found here:

• Java 8: https://www.oracle.com/technetwork/java/javase/downloads/jce8-download-2133166.html

For Java 9 and above, the Unlimited Strength Jurisdiction Policy Files are no longer needed. (For more information see: https://stackoverflow.com/questions/1179672)

Usage on Android

The Android platform ships with a cut-down version of Bouncy Castle. In the past (pre-Android 3.0), this caused conflicts and there was a separate version of the Crypto SDK for Android which used Spongy Castle.

Because there are very few people who use pre-Android 3.0 devices, and the fact that Spongy Castle is not maintained anymore, there is no longer a separate version.

To avoid problems you should reinitialize the Bouncy Castle security provider when your application starts. This can be done by extending Application and using a static initialization block. See following example.

...

import org.bouncycastle.jce.provider.BouncyCastleProvider;

public class DracoonApplication extends Application {
    
    static {
        Security.removeProvider(BouncyCastleProvider.PROVIDER_NAME);
        Security.addProvider(new BouncyCastleProvider());
    }

    ...
    
}

Example

An example can be found here: example/src/main/java/com/dracoon/sdk/crypto/example/Main.java

The example shows the complete encryption workflow, i.e. generate user keypair, validate user keypair, generate file key, encrypt file key, and finally encrypt and decrypt a file.

public static void main(String[] args) throws Exception {
    // --- INITIALIZATION ---
    // Generate key pair
    UserKeyPair userKeyPair = Crypto.generateUserKeyPair(UserKeyPair.Version.RSA2048,
            USER_PASSWORD);
    // Check key pair
    if (!Crypto.checkUserKeyPair(userKeyPair, USER_PASSWORD)) {
        ...
    }

    byte[] plainData = DATA.getBytes("UTF8");

    ...

    // --- ENCRYPTION ---
    // Generate plain file key
    PlainFileKey fileKey = Crypto.generateFileKey(PlainFileKey.Version.AES256GCM);
    // Encrypt blocks
    byte[] encData = encryptData(fileKey, plainData);
    // Encrypt file key
    EncryptedFileKey encFileKey = Crypto.encryptFileKey(fileKey, userKeyPair.getUserPublicKey());

    ...

    // --- DECRYPTION ---
    // Decrypt file key
    PlainFileKey decFileKey = Crypto.decryptFileKey(encFileKey, userKeyPair.getUserPrivateKey(),
            USER_PASSWORD);
    // Decrypt blocks
    byte[] decData = decryptData(decFileKey, encData);

    ...
}

Contribution

If you would like to contribute code, fork the repository and send a pull request. When submitting code, please make every effort to follow existing conventions and style in order to keep the code as readable as possible.

Copyright and License

Copyright Dracoon GmbH. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.