Themis examples for Java and Android

Here you can find simple example projects, showing how to integrate JavaThemis into desktop applications in Java and Android applications in Kotlin.

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⚠️ Repository is archived 📚

We moved the example projects to the main repository to keep them up-to-date more easily:

• docs/examples/android – Android application in Kotlin
• docs/examples/java – desktop application in Java

Examples provided here are not maintained and use JavaThemis 0.13. For up-to-date example projects using the latest version of Themis, please refer to the main repository.

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Learn more about using Themis in Java applications as well as writing Android applications in Kotlin.

How to run?

Java example

1. Install Themis Core and Themis JNI library (see below).
2. Open java-example in IntelliJ IDEA.
3. Run main.java.

Note: If you cannot run the example app because of error like this

Exception in thread "main" java.lang.UnsatisfiedLinkError: <some path>/libthemis_jni.so: libthemis.so.0: cannot open shared object file: No such file or directory

you will have to add LD_LIBRARY_PATH=/usr/local/lib (or wherever the libthemis is stored) to environment variables of the Application main configuration, so the JVM will be able to find it. This magic variable may be used on both Linux and macOS.

If libthemis_jni.so is the one it cannot find, you may want to try adding JVM option java.library.path=/path/to/dir_with_libthemis_jni.so.

Android example

1. Open android-example, import as Android Studio project.
2. Included library Themis for Android via bintray maven repository (see below).
3. Run MainActivitySecureCell as secure data storage or MainActivitySecureMessage to see secure messaging example.

What are these examples?

Client code (both Android and Java) contains simple example for symmetric and asymmetric encryption.

1. Symmetric encryption using Themis Secure Cell. Open main file for Java and MainActivitySecureCell for Android.

encryptDataForStoring()

1.1 Create SecureCell with desired password:

SecureCell sc = new SecureCell(passKey);

1.2. Encrypt data. You will get base64 encoded string as output in console.

SecureCellData encryptedData = sc.protect(password, optionalContext, message);
String encryptedDataString = Base64.getEncoder().encodeToString(encryptedData.getProtectedData());

1.3. Decrypt data previously encrypted. You will get original message as output in console.

byte[] decodedEncryptedString = Base64.getDecoder().decode(encryptedDataString);
SecureCellData encryptedDataFromString = new SecureCellData(decodedEncryptedString, null);

byte[] unprotected = sc.unprotect(password, optionalContext, encryptedDataFromString);
String decryptedString = new String(unprotected);

2. Asymmetric encryption using Themis Secure Message.

2.1 For Java, see main file:

encryptDataForMessaging

2.2 For Android, see MainActivitySecureMessage file:

secureMessageLocal

Themis Interactive simulator

Both examples contain ready-to-use solutions to test asymmetric encryption with Themis Interactive Server. No need to run your own server to check if you have implemented encryption correctly.

For Java check SMessageClient and SSessionClient. For Android check MainActivitySecureMessage and MainActivitySecureSession.

Comprehensive documentation can be found below: https://docs.cossacklabs.com/simulator/interactive/

How to install Themis

For Desktop Java

1. Install Themis Core and Themis JNI libraries.

   Follow the instructions. Linux and macOS are supported.

2. Add Maven Central repository and use java-themis in build.gradle:

   repositories {
       mavenCentral()
   }
   
   dependencies {
       // Add JavaThemis as runtime dependency of your application.
       // Always pin the latest version, you can find it here:
       // https://search.maven.org/artifact/com.cossacklabs.com/java-themis
       implementation 'com.cossacklabs.com:java-themis:0.13.1'
   }
   

   Please note that the package name is different from Android.

For Android

1. Add Maven Central repository to your repositories in build.gradle

repositories {
    google()
    jcenter()
    mavenCentral()
}

2. Link to themis from app/build.gradle

dependencies {
    // Add JavaThemis as runtime dependency of your application.
    // Always pin the latest version, you can find it here:
    // https://search.maven.org/artifact/com.cossacklabs.com/themis
    implementation 'com.cossacklabs.com:themis:0.13.1'
}

Please note that the package name is different from desktop Java.