I want to use org.bouncycastle:bcprov-jdk15on:1.54 in order to generate a public and private key with Bouncy castle.

我想使用org.bouncyCastle：bcprov-jdk15on：1.54来生成带有bouny Castle的公钥和私钥。

I tried to follow this tutorial: https://www.baeldung.com/java-bouncy-castle but several things are not clear.

我尝试遵循这个教程：https://www.baeldung.com/java-bouncy-castle，但有几件事不清楚。

How I can generate a public and private key without using CLI. Can I do this using only Java code and after that get the signature? I don't need to have a .cer or .csr files. I need ot no this in memory.

如何不使用CLI生成公钥和私钥。我可以只使用Java代码来完成这项工作，然后获得签名吗？我不需要有.ercer或.csr文件。我不需要把这些记在记忆里。

EDIT: I tried this code:

编辑：我尝试了以下代码：

import io.jsonwebtoken.lang.Assert;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.junit.jupiter.api.Test;

import javax.xml.bind.DatatypeConverter;
import java.io.ByteArrayInputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Security;
import java.security.Signature;
import java.security.SignatureException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.util.Base64;

public class CertificateGenerateTestApiTest {

    String data; // complete certificate and metadata. We need to get of when we generate a certificate
    String signature; // signature of the certificate

    @Test
    public void certificateGenerationTest()
    {
        // Generate private and public keys
        KeyPair keyPair = generateCertificate();

        PublicKey publicCertificate = keyPair.getPublic();

        // Problem 1 - think how to populate "data" variable from public certificate
        // Problem 2 - think how to populate "signature" variable from public certificate

        // Get public key as byte[] in order later on to be stored into DB
        byte[] originalPublicCertificate = privateCertificateToByte(publicCertificate);

        // Let's say we received some certificate by some web client, and we want to verify it against our original certificate
        byte[] secondPublicCertificateReceivedByClient = cloneByteArrayData(originalPublicCertificate);

        // Verify certificate
        Assert.isTrue(verifyCertificate(secondPublicCertificateReceivedByClient));
    }

    private KeyPair generateCertificate()
    {
        try {
            Security.addProvider(new BouncyCastleProvider());
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA", "BC");
            keyPairGenerator.initialize(2048, new SecureRandom());

            KeyPair keyPair = keyPairGenerator.generateKeyPair();

            return keyPair;
        } catch (NoSuchAlgorithmException | NoSuchProviderException e) {
            e.printStackTrace();
        }
        return null;
    }

    private boolean verifyCertificate(byte[] secondPublicCertificateReceivedByClient)
    {
        PublicKey publicKey = getKeyPayload(byteToString(secondPublicCertificateReceivedByClient));
        boolean verified = false;

        try {
            verified = verifySignature(data.getBytes("UTF8"), publicKey,
                    DatatypeConverter.parseHexBinary(signature));
        } catch (SignatureException | UnsupportedEncodingException e) {

        } catch (NoSuchAlgorithmException | InvalidKeyException e) {
            e.printStackTrace();
        }
        return verified;
    }

    private boolean verifySignature(byte[] data, PublicKey key, byte[] signature)
            throws NoSuchAlgorithmException, InvalidKeyException, SignatureException {
        Signature signer = Signature.getInstance("SHA1withDSA");
        signer.initVerify(key);
        signer.update(data);
        try {
            if (signer.verify(signature)) {
                return true;
            }
        } catch (SignatureException e) {
            e.printStackTrace();
        }
        return false;
    }

    private PublicKey getKeyPayload(String certificateString) {
        try {
            CertificateFactory cf = CertificateFactory.getInstance("X.509");
            ByteArrayInputStream bis =
                    new ByteArrayInputStream(certificateString.getBytes(StandardCharsets.UTF_8));

            Certificate certificate = null;
            while (bis.available() > 0) {
                certificate = cf.generateCertificate(bis);
            }

            return (certificate == null) ? null : certificate.getPublicKey();
        } catch (CertificateException e) {
            e.printStackTrace();
        }
        return null;
    }

    private String byteToString(byte[] publicKeyBytes)
    {
        return Base64.getEncoder().encodeToString(publicKeyBytes);
    }

    private byte[] privateCertificateToByte(PublicKey publicCertificate)
    {
        return publicCertificate.getEncoded();
    }

    /**
     * Clone byte[] data
     */
    private byte[] cloneByteArrayData(byte[] sourceArray)
    {
        int sourceOffset = 0; /* Starting index in the source array */;
        int destinationOffset = 0; // Starting index in the destination array
        byte[] destinationArray = new byte[sourceArray.length];

        for (int i = 0; i < sourceArray.length; i++) {
            destinationArray[destinationOffset + i] = sourceArray[sourceOffset + i];
        }

        return destinationArray;
    }
}

I get:

我得到了：

java.security.cert.CertificateException: Could not parse certificate: java.io.IOException: Empty input

Your code is quite chaotic with regard to naming. You cannot magically turn a key into a certificate just by naming it so. You create a key pair and fetch the public key, always calling it a certificate. An apple is not an orange, even if you call it one.

您的代码在命名方面相当混乱。您不能仅仅通过命名就能神奇地将密钥转换为证书。您创建一个密钥对并获取公钥，始终将其称为证书。苹果不是橙子，即使你把它叫做橙子。

Anyway, you did not post your full stack trace. If you had, it would have been apparent why your program throws this exception:

无论如何，您没有发布完整的堆栈跟踪。如果您有，那么您的程序抛出这个异常的原因就很明显了：

java.security.cert.CertificateException: Could not parse certificate: java.io.IOException: Empty input
    at sun.security.provider.X509Factory.engineGenerateCertificate(X509Factory.java:114)
    at java.security.cert.CertificateFactory.generateCertificate(CertificateFactory.java:339)
    at CertificateGenerateTestApiTest.getKeyPayload(CertificateGenerateTestApiTest.java:98)
    at CertificateGenerateTestApiTest.verifyCertificate(CertificateGenerateTestApiTest.java:61)
    at CertificateGenerateTestApiTest.main(CertificateGenerateTestApiTest.java:45)
Caused by: java.io.IOException: Empty input
    at sun.security.provider.X509Factory.engineGenerateCertificate(X509Factory.java:110)
    ... 4 more
Exception in thread "main" java.lang.NullPointerException
    at CertificateGenerateTestApiTest.verifyCertificate(CertificateGenerateTestApiTest.java:65)
    at CertificateGenerateTestApiTest.main(CertificateGenerateTestApiTest.java:45)

My line numbers are a bit different after pasting your code into my IDE and adjusting a few things to make it run without JUnit, but the basic information stays the same:

在将代码粘贴到我的IDE中并调整了一些设置以使其在没有JUnit的情况下运行后，我的行号有点不同，但基本信息保持不变：

You never initialise the data field in your class, but are trying to call data.getBytes("UTF8"). That cannot work.

您从未初始化类中的数据字段，而是尝试调用data.getBytes(“UTF8”)。这是行不通的。

There are many other problems in your code, but this one answers your question why this error message occurs.

您的代码中还有许多其他问题，但这个问题回答了您为什么会出现此错误消息的问题。