Waves Crypto for Java

Table of contents

• How to install
• Quick start
• Cryptography
  • Seed phrase
  • Account seed
  • Private and public keys
  • Address
  • Signing
• Base encodings
• Hashing algorithms
• Merkle tree
• RSA

How to install

1. Go to the Waves-Crypto page at Maven Central;
2. open the latest version page of the library;
3. copy&paste dependency template into your project management tool config file (Maven, Gradle, etc).

Quick start

Here's a complete example of how to generate a new Waves account:

import com.wavesplatform.crypto.Crypto;
import com.wavesplatform.crypto.base.Base58;

public class WavesAccount {
    
    public static final byte MAINNET = 'W';
    public static final byte TESTNET = 'T';
    
    public static void main() {
        String seedPhrase = Crypto.getRandomSeedPhrase();
        
        byte[] accountSeed = Crypto.getAccountSeed(seedPhrase);
        byte[] privateKey = Crypto.getPrivateKey(accountSeed);
        byte[] publicKey = Crypto.getPublicKey(privateKey);
        
        byte[] publicKeyHash = Crypto.getPublicKeyHash(publicKey);
        byte[] mainnetAddress = Crypto.getAddress(MAINNET, publicKeyHash);
        byte[] testnetAddress = Crypto.getAddress(TESTNET, publicKeyHash);

        System.out.println("# Account details");
        System.out.println("Seed phrase:\t" + seedPhrase);
        System.out.println("Private key:\t" + Base58.encode(privateKey));
        System.out.println("Public key:\t" + Base58.encode(publicKey));
        System.out.println("Mainnet address:\t" + Base58.encode(mainnetAddress));
        System.out.println("Testnet address:\t" + Base58.encode(testnetAddress));
    }
}

Cryptography

Please read about Waves cryptography on the official documentation page.

Seed phrase

Seed phrase also means Recovery phrase.

This is usually a sequence of several words, but technically it's just an array of arbitrary bytes.

Human-readable phrase

String seedPhraseOf15WordsByDefault = Crypto.getRandomSeedPhrase();
String seedPhraseOfCustomWordsNumber = Crypto.getRandomSeedPhrase(15);

Random bytes phrase

byte[] seedPhraseOf255BytesByDefault = Crypto.getRandomSeedBytes();
byte[] seedPhraseOfCustomNumberOfBytes = Crypto.getRandomSeedBytes(255);

Account seed

Account seed is a hash of seed phrase and nonce.

Nonce allows creating multiple addresses from a single seed phrase.

The default nonce is 0.

byte[] accountSeedWithNonce0ByDefault = Crypto.getAccountSeed(seedPhrase);
byte[] accountSeedWithSpecificNonce = Crypto.getAccountSeed(seedPhrase, 1);

Private and public keys

From account seed, you can calculate a pair of private and public keys.

byte[] privateKey = Crypto.getPrivateKey(accountSeed);
byte[] publicKey = Crypto.getPublicKey(privateKey);

Address

Account address contains hash of public key, so you need to calculate that hash first.

byte chainId = 'T';
byte[] publicKeyHash = Crypto.getPublicKeyHash(publicKey);

byte[] address = Crypto.getAddress(chainId, publicKeyHash);

Signing

If you have generated an account, you can sign messages with private key and validate resulting signature with public key.

byte[] message = new Random().nextBytes(new byte[32]);

byte[] proof = Crypto.sign(privateKey, message);
boolean isValid = Crypto.isProofValid(publicKey, message, proof);

Base encodings

In the Waves blockchain, all binary data is presented in Base Encodings:

• Base58 is used for "short" values like:
  • private and public keys
  • addresses
  • proofs
  • transaction id
  • asset id
• Base64 is used for potentially long values like:
  • compiled Ride scripts
  • binary arguments of smart contract invocations
  • binary entries in account data storage
• Base16 is available in smart contracts for any purpose.

byte[] message = new Random().nextBytes(new byte[32]);

String base58Encoded = Base58.encode(message);
String base64Encoded = Base64.encode(message);
String base16Encoded = Base16.encode(message);

byte[] base58Decoded = Base58.decode(base58Encoded);
byte[] base64Decoded = Base64.decode(base64Encoded);
byte[] base16Decoded = Base16.decode(base16Encoded);

All decoded results are equal to the initial message.

Hashing algorithms

There are supported hashing algorithms:

• sha256
• blake2b256
• keccak256

byte[] message = new Random().nextBytes(new byte[32]);

byte[] shaHash = Hash.sha256(message);
byte[] blakeHash = Hash.blake(message);
byte[] keccakHash = Hash.keccak(message);

// the same as blake hashing
byte[] fastHash = Hash.fastHash(message);

// sequential hashing with blake and then keccak
byte[] secureHash = Hash.secureHash(message);

Merkle tree

TBD... see TestMerkleTree for usage examples.

RSA

TBD... see TestRsa for usage examples.