Provotum Backend

Endpoints

The different endpoints maintained by the Backen application are described in detail here:

• RESTful Interface
• Websocket Interface

Installation

Follow the steps below for setting up your development environment.

🚧 NOTE: The web3j wrappers are currently only working with geth 1.7.3 and below 🚧

Requirements

• The solidity compiler solc. Obtainable using brew as described in http://solidity.readthedocs.io/en/v0.4.21/installing-solidity.html:

   brew update
   brew upgrade
   brew tap ethereum/ethereum
   brew install solidity
   brew linkapps solidity

• Clone this repo: git clone git@github.com:provotum/backend.git && cd backend
• Init submodule: git submodule init && git submodule update --recursive.
• Install web3j for contract to Java wrapper compilation: brew install web3j.
• Adjust the application properties in src/main/resources/application.properties:

   # Evaluation
   evaluation.output=/tmp/evaluation
   # Ethereum and Web3J
   ethereum.web3j.rpchost=http://sealer01.provotum.ch:80
   ethereum.wallet.location=src/main/resources/wallets/local-net.json
   ethereum.wallet.password=password123
   # Encryption
   security.output.electionpublickey=src/main/resources/publickey.pub
   security.output.electionprivatekey=src/main/resources/privatekey.priv
   security.output.rsapublickey=src/main/resources/rsa-publickey.pub
   security.output.rsaprivatekey=src/main/resources/rsa-privatekey.priv
   # Spring Boot Configuration
   server.port=8080

• evaluation.output: Where the evaluation output should be stored. Contains time measurements of different operations.
• ethereum.web3j.rpchost: The host on which a geth node (with the RPC interface enabled) is running. MUST start with http resp. https.
• ethereum.wallet.location: The path to a pre-allocated wallet which is used to deploy the contracts
• ethereum.wallet.password: The password for the above wallet.
• security.output.electionpublickey: Where the election public key should be saved.
• security.output.electionprivatekey: Where the election private key should be saved.
• security.output.rsapublickey: The path to the RSA public key used for encrypting the random value parameter R of an ElGamal ciphertext.
• security.output.rsaprivatekey: The path to the RSA private key used for encrypting the random value parameter R of an ElGamal ciphertext.
• server.port: The port on which the backend should be accessible.

Development

Compile wrapper for contracts

Within the project directory use the Makefile to compile smart contracts and generate their wrappers using Web3j:

• make compile: Will take all *.sol files from eth-contracts/contracts and compile them to eth-contracts-build.
• make wrappers: Will the build files and generate Java wrappers for them in src/main/java/org.provotum/ethereum/wrappers
• make clean: Will remove all compiled contracts from eth-contracts-build

Running the App

To run the app with the configured parameters, invoke

   mvn spring-boot:run

Known Issues

NOTE: If it seems that the contract creations do not reach the sealer nodes, you should increase the maximum heap space of Java:

mvn spring-boot:run -Drun.jvmArguments="-Xmx768m" -Drun.profiles=dev