Fluree Crypto Java Library

A Java library that provides cryptographic utilities for generating keypairs, signing and verifying JSON Web Signatures (JWS), and deriving account IDs for use with Fluree.

Features

• Generate Keypair: Generate a secp256k1 keypair.
• Create JWS: Sign a payload using a private key and create a JWS.
• Verify JWS: Verify a JWS and retrieve the payload and public key used to sign it.
• Derive Public Key: Derive a public key from a private key.
• Derive Account ID from Private Key: Derive a Fluree-compatible account ID from a private key.
• Derive Account ID from Public Key: Derive a Fluree-compatible account ID from a public key.

Installation

Maven

Add the following dependency to your pom.xml:

<dependency>
    <groupId>com.fluree</groupId>
    <artifactId>crypto</artifactId>
    <version>1.0.0</version>
</dependency>

Gradle

Add the following dependency to your build.gradle:

implementation 'com.fluree:crypto:1.0.0'

Usage

1. Generate Keypair

You can generate a secp256k1 keypair using the generateKeyPair method.

import com.fluree.crypto.Crypto;
import com.fluree.crypto.Keypair;

public class Example {
    public static void main(String[] args) throws Exception {
        Keypair keypair = Crypto.generateKeyPair();
        System.out.println("Private Key: " + keypair.getPrivateKey());
        System.out.println("Public Key: " + keypair.getPublicKey());
    }
}

2. Create JWS

Sign a payload using a private key and create a JWS.

import com.fluree.crypto.Crypto;

public class Example {
    public static void main(String[] args) throws Exception {
        Keypair keypair = Crypto.generateKeyPair();
        String privateKey = keypair.getPrivateKey();
        String payload = "{\"foo\":\"bar\"}";
        String jws = Crypto.createJws(payload, privateKey);
        System.out.println("JWS: " + jws);
    }
}

3. Verify JWS

Verify a JWS and retrieve the payload and public key used to sign it.

import com.fluree.crypto.Crypto;
import java.util.HashMap;

public class Example {
    public static void main(String[] args) throws Exception {
        Keypair keypair = Crypto.generateKeyPair();
        String privateKey = keypair.getPrivateKey();
        String publicKey = keypair.getPublicKey();
        String payload = "{\"foo\":\"bar\"}";
        String jws = Crypto.createJws(payload, privateKey);
        HashMap<String, String> result = Crypto.verifyJws(jws);
        System.out.println("Payload: " + result.get("payload"));
        System.out.println("Public Key: " + result.get("pubkey"));
        Assert.assertEquals(result.get("payload"), payload);
        Assert.assertEquals(result.get("pubkey"), publicKey);
    }
}

4. Derive Public Key from Private Key

Derive the public key from a private key in hexadecimal format.

import com.fluree.crypto.Crypto;

public class Example {
    public static void main(String[] args) {
        Keypair keypair = Crypto.generateKeyPair();
        String privateKey = keypair.getPrivateKey();
        String publicKey = Crypto.pubKeyFromPrivate(privateKey);
        System.out.println("Public Key: " + publicKey);
    }
}

5. Derive Account ID from Private Key

Derive a Fluree-compatible account ID from a private key.

import com.fluree.crypto.Crypto;

public class Example {
    public static void main(String[] args) throws Exception {
        Keypair keypair = Crypto.generateKeyPair();
        String privateKey = keypair.getPrivateKey();
        String accountId = Crypto.accountIdFromPrivateKey(privateKey);
        System.out.println("Account ID: " + accountId);
    }
}

6. Derive Account ID from Public Key

Derive a Fluree-compatible account ID from a public key.

import com.fluree.crypto.Crypto;

public class Example {
    public static void main(String[] args) throws Exception {
        Keypair keypair = Crypto.generateKeyPair();
        String privateKey = keypair.getPrivateKey();
        String publicKey = Crypto.pubKeyFromPrivate(privateKey);
        String accountId = Crypto.accountIdFromPublicKey(publicKey);
        System.out.println("Account ID: " + accountId);
    }
}

Methods Overview

createJws(String payload, String privateKeyHex)

• Description: Creates a JWS (JSON Web Signature) using the provided payload and private key.
• Parameters:
  • payload: The stringified payload to sign.
  • privateKeyHex: The private key used to sign the payload (in hexadecimal format).
• Returns: A JWS string.
• Throws: Exception if the JWS creation fails.

verifyJws(String jwsString)

• Description: Verifies a JWS and returns a map containing the payload and public key.
• Parameters:
  • jwsString: The JWS string to verify.
• Returns:
  • A HashMap<String, String> containing the payload and pubkey.
  • null if the verification fails.

generateKeyPair()

• Description: Generates a secp256k1 keypair.
• Returns: A Keypair object containing the public and private keys.
• Throws: Exception if keypair generation fails.

pubKeyFromPrivate(String privateKeyHex)

• Description: Derives the public key from a private key.
• Parameters:
  • privateKeyHex: The private key (in hexadecimal format).
• Returns: The public key (in hexadecimal format).

accountIdFromPrivateKey(String privateKeyHex)

• Description: Derives a Fluree-compatible account ID from a private key.
• Parameters:
  • privateKeyHex: The private key (in hexadecimal format).
• Returns: The account ID (in base58 encoding).
• Throws: Exception if the account ID derivation fails.

accountIdFromPublicKey(String publicKey)

• Description: Derives a Fluree-compatible account ID from a public key.
• Parameters:
  • publicKey: The public key (in hexadecimal format).
• Returns: The account ID (in base58 encoding).
• Throws: Exception if the account ID derivation fails.

Development

Building the Project

To build the project, use Maven:

mvn clean install

Running Tests

To run tests, use:

mvn test

Contributing

Contributions are welcome! Please open an issue or submit a pull request.

License

This project is licensed under the Apache 2.0 License - see the LICENSE file for details.

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Happy coding! 🌟