java-algorand-sdk

AlgoSDK is a Java library for communicating and interacting with the Algorand network. It contains a REST client for accessing algod instances over the web, and also exposes functionality for generating keypairs, mnemonics, creating transactions, signing transactions, and serializing data across the network.

Prerequisites

Java 8+ and Android minSdkVersion 26+

Installation

Maven:

<dependency>
    <groupId>com.algorand</groupId>
    <artifactId>algosdk</artifactId>
    <version>2.10.1</version>
</dependency>

Quickstart

This program connects to a running sandbox private network, creates a payment transaction between two of the accounts, signs it with kmd, and reads result from Indexer.

import com.algorand.algosdk.account.Account;
import com.algorand.algosdk.crypto.Address;
import com.algorand.algosdk.kmd.client.ApiException;
import com.algorand.algosdk.kmd.client.KmdClient;
import com.algorand.algosdk.kmd.client.api.KmdApi;
import com.algorand.algosdk.kmd.client.model.*;
import com.algorand.algosdk.transaction.SignedTransaction;
import com.algorand.algosdk.transaction.Transaction;
import com.algorand.algosdk.util.Encoder;
import com.algorand.algosdk.v2.client.common.AlgodClient;
import com.algorand.algosdk.v2.client.common.IndexerClient;
import com.algorand.algosdk.v2.client.common.Response;
import com.algorand.algosdk.v2.client.model.PendingTransactionResponse;
import com.algorand.algosdk.v2.client.model.PostTransactionsResponse;
import com.algorand.algosdk.v2.client.model.TransactionsResponse;

import java.io.IOException;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Main {
    private static String token = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
    private static KmdApi kmd = null;

    public static void main(String[] args) throws Exception {
        // Initialize algod/indexer v2 clients.
        AlgodClient algod = new AlgodClient("http://localhost", 4001, token);
        IndexerClient indexer = new IndexerClient("http://localhost", 8980);

        // Initialize KMD v1 client
        KmdClient kmdClient = new KmdClient();
        kmdClient.setBasePath("http://localhost:4002");
        kmdClient.setApiKey(token);
        kmd = new KmdApi(kmdClient);

        // Get accounts from sandbox.
        String walletHandle = getDefaultWalletHandle();
        List<Address> accounts  = getWalletAccounts(walletHandle);

        // Create a payment transaction
        Transaction tx1 = Transaction.PaymentTransactionBuilder()
                .lookupParams(algod) // lookup fee, firstValid, lastValid
                .sender(accounts.get(0))
                .receiver(accounts.get(1))
                .amount(1000000)
                .noteUTF8("test transaction!")
                .build();

        // Sign with KMD
        SignedTransaction stx1a = signTransactionWithKMD(tx1, walletHandle);
        byte[] stx1aBytes = Encoder.encodeToMsgPack(stx1a);

        // Sign with private key
        byte[] privateKey = lookupPrivateKey(accounts.get(0), walletHandle);
        Account account = new Account(privateKey);
        SignedTransaction stx1b = account.signTransaction(tx1);
        byte[] stx1bBytes = Encoder.encodeToMsgPack(stx1b);

        // KMD and signing directly should both be the same.
        if (!Arrays.equals(stx1aBytes, stx1bBytes)) {
            throw new RuntimeException("KMD disagrees with the manual signature!");
        }

        // Send transaction
        Response<PostTransactionsResponse> post = algod.RawTransaction().rawtxn(stx1aBytes).execute();
        if (!post.isSuccessful()) {
            throw new RuntimeException("Failed to post transaction");
        }

        // Wait for confirmation
        boolean done = false;
        while (!done) {
            Response<PendingTransactionResponse> txInfo = algod.PendingTransactionInformation(post.body().txId).execute();
            if (!txInfo.isSuccessful()) {
                throw new RuntimeException("Failed to check on tx progress");
            }
            if (txInfo.body().confirmedRound != null) {
                done = true;
            }
        }

        // Wait for indexer to index the round.
        Thread.sleep(5000);

        // Query indexer for the transaction
        Response<TransactionsResponse> transactions = indexer.searchForTransactions()
                .txid(post.body().txId)
                .execute();

        if (!transactions.isSuccessful()) {
            throw new RuntimeException("Failed to lookup transaction");
        }

        System.out.println("Transaction received! \n" + transactions.toString());
    }

    public static SignedTransaction signTransactionWithKMD(Transaction tx, String walletHandle) throws IOException, ApiException {
        SignTransactionRequest req = new SignTransactionRequest();
        req.transaction(Encoder.encodeToMsgPack(tx));
        req.setWalletHandleToken(walletHandle);
        req.setWalletPassword("");
        byte[] stxBytes = kmd.signTransaction(req).getSignedTransaction();
        return Encoder.decodeFromMsgPack(stxBytes, SignedTransaction.class);
    }

    public static byte[] lookupPrivateKey(Address addr, String walletHandle) throws ApiException {
        ExportKeyRequest req = new ExportKeyRequest();
        req.setAddress(addr.toString());
        req.setWalletHandleToken(walletHandle);
        req.setWalletPassword("");
        return kmd.exportKey(req).getPrivateKey();
    }

    public static String getDefaultWalletHandle() throws ApiException {
        for (APIV1Wallet w : kmd.listWallets().getWallets()) {
            if (w.getName().equals("unencrypted-default-wallet")) {
                InitWalletHandleTokenRequest tokenreq = new InitWalletHandleTokenRequest();
                tokenreq.setWalletId(w.getId());
                tokenreq.setWalletPassword("");
                return kmd.initWalletHandleToken(tokenreq).getWalletHandleToken();
            }
        }
        throw new RuntimeException("Default wallet not found.");
    }

    public static List<Address> getWalletAccounts(String walletHandle) throws ApiException, NoSuchAlgorithmException {
        List<Address> accounts = new ArrayList<>();

        ListKeysRequest keysRequest = new ListKeysRequest();
        keysRequest.setWalletHandleToken(walletHandle);
        for (String addr : kmd.listKeysInWallet(keysRequest).getAddresses()) {
            accounts.add(new Address(addr));
        }

        return accounts;
    }
}

Documentation

Javadoc can be found at https://algorand.github.io/java-algorand-sdk.
Additional resources and code samples are located at https://developer.algorand.org.

Cryptography

AlgoSDK depends on org.bouncycastle:bcprov-jdk15to18:1.78 for Ed25519 signatures, sha512/256 digests, and deserializing X.509-encoded Ed25519 private keys. The latter is the only explicit dependency on an external crypto library - all other references are abstracted through the JCA.

Java 9+

When using cryptographic functionality, and Java9+, you may run into the following warning:

WARNING: Illegal reflective access by org.bouncycastle.jcajce.provider.drbg.DRBG

This is known behavior, caused by more restrictive language features in Java 9+, that Bouncy Castle has yet to support. This warning can be suppressed safely. We will monitor cryptographic packages for updates or alternative implementations.

Contributing to this Project

build

This project uses Maven.

To build

~$ mvn package

To test

We are using separate version targets for production and testing to allow using JUnit5 for tests. Some IDEs, like IDEA do not support this very well. To workaround the issue a special ide profile should be enabled if your IDE does not support mixed target and testTarget versions. Regardless of IDE support, the tests can be run from the command line. In this case clean is used in case an incremental build was made by the IDE with Java8.

~$ mvn clean test

There is also a special integration test environment, and shared tests. To run these use the Makefile:

~$ make docker-test

To stand up the test harness, without running the entire test suite use the Makefile:

~$ make harness

You can then run specific cucumber-based unit and integration tests directly.

deploying artifacts

You can deploy artifacts to Maven Central and Github Pages using the Publish and Release Workflows with appropriate permissioning.

Testing

Many cross-SDK tests are defined in algorand-sdk-testing. Some are integration tests with additional dependencies. These dependencies are containerized in a docker file, which can be executed with make docker-test.

It is occasionally useful to run locally, or against alternate integration branches. To do this:

1. Install feature files for your test branch "./run_integration_tests.sh -feature-only -test-branch "
2. Run locally with make integration and make unit, or from the IDE by running "RunCucumberUnitTest.java"

Android Support

Significant work has been taken to ensure Android compatibility (in particular for minSdkVersion 26). Note that the default crypto provider on Android does not provide ed25519 signatures, so you will need to provide your own (e.g. BouncyCastle).

Algod V2 and Indexer Code Generation

The classes com.algorand.algosdk.v2.client.algod.\*, com.algorand.algosdk.v2.client.indexer.\*, com.algorand.algosdk.v2.client.common.AlgodClient, and com.algorand.algosdk.v2.client.common.IndexerClient are generated from OpenAPI specifications in: algod.oas2.json and indexer.oas2.json.

The specification files can be obtained from:

• algod.oas2.json
• indexer.oas2.json

A testing framework can also be generated with: com.algorand.sdkutils.RunQueryMapperGenerator and the tests run from com.algorand.sdkutils.RunAlgodV2Tests and com.algorand.sdkutils.RunIndexerTests

Regenerate the Client Code

The actual generation is done using the generate_java.sh script in the generator repo.

Updating the kmd REST client

The kmd REST client has not been upgraded to use the new code generation, it is still largely autogenerated by swagger-codegen. [https://github.com/swagger-api/swagger-codegen]

To regenerate the clients, first, check out the latest swagger-codegen from the github repo. (In particular, the Homebrew version is out of date and fails to handle raw byte arrays properly). Note OpenAPI 2.0 doesn't support unsigned types. Luckily we don't have any uint32 types in algod, so we can do a lossless type-mapping fromt uint64->int64 (Long) -> BigInteger:

curl http://localhost:8080/swagger.json | sed -e 's/uint32/int64/g' > temp.json
swagger-codegen generate -i temp.json -l java -c config.json

config.json looks like:

{
  "library": "okhttp-gson",
  "java8": false,
  "hideGenerationTimestamp": true,
  "serializableModel": false,
  "supportJava6": true,
  "invokerPackage": "com.algorand.algosdk.{kmd or algod}.client",
  "apiPackage": "com.algorand.algosdk.{kmd or algod}.client.api",
  "modelPackage": "com.algorand.algosdk.{kmd or algod}.client.model"
}

Make sure you convert all uint32 types to Long types.

The generated code (as of April 2019) has one circular dependency involving client.Pair. The client package depends on client.auth, but client.auth uses client.Pair which is in the client package. One more problem is that uint64 is not a valid format in OpenAPI 2.0; however, we need to send large integers to the algod API (kmd is fine). To resolve this, we do the following manual pass on generated code:

• Move Pair.java into the client.lib package
• Find-and-replace Integer with BigInteger (for uint64), Long (for uint32), etc. in com.algorand.algosdk.algod and subpackages (unnecessary for algod)
• Run an Optimize Imports operation on generated code, to minimize dependencies.

Note that msgpack-java is good at using the minimal representation.