Configure RSA512 algorithm for com.auth0.jwt.JWT using an RSA private/public key generated by openssl

JwtTest.java

import com.auth0.jwt.JWT;
import com.auth0.jwt.algorithms.Algorithm;
import org.bouncycastle.util.io.pem.PemReader;
import org.junit.Test;

import java.io.BufferedReader;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.KeyFactory;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * Configure RSA512 algorithm for com.auth0.jwt.JWT using an RSA private/public key generated by openssl.
 * 
 * See also: https://www.baeldung.com/java-read-pem-file-keys
 */
public class JwtTest {
	@Test
	public void test() throws Exception {
		// Generate RSA private/public key
		// $ openssl genrsa -out private.key 4096
		// $ openssl rsa -in private.key -pubout -out public.key
		// $ openssl pkcs8 -topk8 -nocrypt -in private.key -out private.pkcs8.key
		KeyFactory kf = KeyFactory.getInstance("RSA");
		RSAPublicKey publicKey;
		try (BufferedReader reader = Files.newBufferedReader(Paths.get("public.key"))) {
			byte[] publicKeyBytes = new PemReader(reader).readPemObject().getContent();
			publicKey = (RSAPublicKey) kf.generatePublic(new X509EncodedKeySpec(publicKeyBytes));
		}
		RSAPrivateKey privateKey;
		try (BufferedReader reader = Files.newBufferedReader(Paths.get("private.pkcs8.key"))) {
			byte[] privateKeyBytes = new PemReader(reader).readPemObject().getContent();
			privateKey = (RSAPrivateKey) kf.generatePrivate(new PKCS8EncodedKeySpec(privateKeyBytes));
		}
		Algorithm algorithm = Algorithm.RSA512(publicKey, privateKey);
		String token = JWT.create().withSubject("foobar").sign(algorithm);
		System.out.println(token);
	}
}