Example app to decrypt Giosg chat messages with Java

This is a simple Java app that decrypts chat messages from Giosg chat messages. It uses customers private key provided in PEM format to decrypt the AES key of the encrypted messages.

App is provided as an example how to implement decryption in Java but could be used as stand alone tool also.

See usage instructions below.

Example data is provided in the example_data directory along with example private key in example_keys.

Pre build binaries

Pre build binaries can be found in the bin directory. You can run the app like this:

java -cp bin/decrypt-app-1.0-SNAPSHOT-jar-with-dependencies.jar com.giosg.decryptapp.App -k <privatekey.pem> -p <privatekey password> -c <chat.json> -m <messages.json>. You can also specify to output decrypted messages to a file with -o <output file>.

Project comes with some example data so you can test it with the following command:

java -cp bin/decrypt-app-1.0-SNAPSHOT-jar-with-dependencies.jar com.giosg.decryptapp.App -k example_keys/private.pem -p salaisuus -c example_data/chat.json -m example_data/messages.json

Installation and building the app

Make sure you have Maven installed (version 3.6.3 was used to build this app): mvn --version

Install dependencies: mvn dependency:resolve

Build assembly package with all dependencies bundled into it: mvn clean compile assembly:single

Run the app: java -cp target/decrypt-app-1.0-SNAPSHOT-jar-with-dependencies.jar com.giosg.decryptapp.App

usage: -k <privatekey.pem> -p <privatekey password> -c <chat.json> -m
          <messages.json> -o <output file>
 -c,--chat <arg>       Chat JSON file path
 -h,--help             Show help
 -k,--key <arg>        Private key PEM file path
 -m,--messages <arg>   Messages JSON file path
 -o,--out <arg>        Output file path
 -p,--pass <arg>       Private key password

While developing you can also build and run the app with provided test data with ./build_and_run.sh.