MainClass.java Source code

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Here is the source code for MainClass.java

Source

import java.io.OutputStreamWriter;
import java.math.BigInteger;
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.Security;
import java.security.SignatureException;
import java.security.cert.X509Certificate;
import java.util.Date;
import java.util.Enumeration;

import javax.security.auth.x500.X500Principal;

import org.bouncycastle.asn1.ASN1Set;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.pkcs.Attribute;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.x509.BasicConstraints;
import org.bouncycastle.asn1.x509.ExtendedKeyUsage;
import org.bouncycastle.asn1.x509.KeyPurposeId;
import org.bouncycastle.asn1.x509.KeyUsage;
import org.bouncycastle.asn1.x509.X509Extension;
import org.bouncycastle.asn1.x509.X509Extensions;
import org.bouncycastle.jce.PKCS10CertificationRequest;
import org.bouncycastle.openssl.PEMWriter;
import org.bouncycastle.x509.X509V1CertificateGenerator;
import org.bouncycastle.x509.X509V3CertificateGenerator;
import org.bouncycastle.x509.extension.AuthorityKeyIdentifierStructure;
import org.bouncycastle.x509.extension.SubjectKeyIdentifierStructure;

public class MainClass {
    public static KeyPair generateRSAKeyPair() throws Exception {
        KeyPairGenerator kpGen = KeyPairGenerator.getInstance("RSA", "BC");
        kpGen.initialize(1024, new SecureRandom());
        return kpGen.generateKeyPair();
    }

    public static PKCS10CertificationRequest generateRequest(KeyPair pair) throws Exception {
        return new PKCS10CertificationRequest("SHA256withRSA", new X500Principal("CN=Requested Test Certificate"),
                pair.getPublic(), null, pair.getPrivate());
    }

    public static X509Certificate generateV1Certificate(KeyPair pair)
            throws InvalidKeyException, NoSuchProviderException, SignatureException {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

        X509V1CertificateGenerator certGen = new X509V1CertificateGenerator();

        certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis()));
        certGen.setIssuerDN(new X500Principal("CN=Test Certificate"));
        certGen.setNotBefore(new Date(System.currentTimeMillis() - 10000));
        certGen.setNotAfter(new Date(System.currentTimeMillis() + 10000));
        certGen.setSubjectDN(new X500Principal("CN=Test Certificate"));
        certGen.setPublicKey(pair.getPublic());
        certGen.setSignatureAlgorithm("SHA256WithRSAEncryption");

        return certGen.generateX509Certificate(pair.getPrivate(), "BC");
    }

    public static X509Certificate[] buildChain() throws Exception {
        KeyPair pair = generateRSAKeyPair();
        PKCS10CertificationRequest request = generateRequest(pair);

        KeyPair rootPair = generateRSAKeyPair();
        X509Certificate rootCert = generateV1Certificate(rootPair);

        X509V3CertificateGenerator certGen = new X509V3CertificateGenerator();

        certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis()));
        certGen.setIssuerDN(rootCert.getSubjectX500Principal());
        certGen.setNotBefore(new Date(System.currentTimeMillis()));
        certGen.setNotAfter(new Date(System.currentTimeMillis() + 10000));
        certGen.setSubjectDN(request.getCertificationRequestInfo().getSubject());
        certGen.setPublicKey(request.getPublicKey("BC"));
        certGen.setSignatureAlgorithm("SHA256WithRSAEncryption");

        certGen.addExtension(X509Extensions.AuthorityKeyIdentifier, false,
                new AuthorityKeyIdentifierStructure(rootCert));

        certGen.addExtension(X509Extensions.SubjectKeyIdentifier,

                false, new SubjectKeyIdentifierStructure(request.getPublicKey("BC")));

        certGen.addExtension(X509Extensions.BasicConstraints, true, new BasicConstraints(false));

        certGen.addExtension(X509Extensions.KeyUsage, true,
                new KeyUsage(KeyUsage.digitalSignature | KeyUsage.keyEncipherment));

        certGen.addExtension(X509Extensions.ExtendedKeyUsage, true,
                new ExtendedKeyUsage(KeyPurposeId.id_kp_serverAuth));

        ASN1Set attributes = request.getCertificationRequestInfo().getAttributes();

        for (int i = 0; i != attributes.size(); i++) {
            Attribute attr = Attribute.getInstance(attributes.getObjectAt(i));

            if (attr.getAttrType().equals(PKCSObjectIdentifiers.pkcs_9_at_extensionRequest)) {
                X509Extensions extensions = X509Extensions.getInstance(attr.getAttrValues().getObjectAt(0));

                Enumeration e = extensions.oids();
                while (e.hasMoreElements()) {
                    DERObjectIdentifier oid = (DERObjectIdentifier) e.nextElement();
                    X509Extension ext = extensions.getExtension(oid);

                    certGen.addExtension(oid, ext.isCritical(), ext.getValue().getOctets());
                }
            }
        }
        X509Certificate issuedCert = certGen.generateX509Certificate(rootPair.getPrivate());

        return new X509Certificate[] { issuedCert, rootCert };
    }

    public static void main(String[] args) throws Exception {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
        X509Certificate[] chain = buildChain();

        PEMWriter pemWrt = new PEMWriter(new OutputStreamWriter(System.out));

        pemWrt.writeObject(chain[0]);
        pemWrt.writeObject(chain[1]);

        pemWrt.close();
    }
}