cloudeventbus.pki.CertificateUtils.java Source code

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/*
 *   Copyright (c) 2012 Mike Heath.  All rights reserved.
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 *
 */
package cloudeventbus.pki;

import cloudeventbus.Subject;
import org.apache.commons.codec.binary.Base64InputStream;
import org.apache.commons.codec.binary.Base64OutputStream;

import javax.crypto.Cipher;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

/**
 * @author Mike Heath <elcapo@gmail.com>
 */
public class CertificateUtils {

    public static final int KEY_SIZE = 2048;

    public static final int DEFAULT_CHALLENGE_LENGTH = 64;

    private static final ThreadLocal<SecureRandom> secureRandom = new ThreadLocal<SecureRandom>() {
        @Override
        protected SecureRandom initialValue() {
            return new SecureRandom();
        }
    };

    public static KeyPair generateKeyPair() {
        try {
            final KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(KEY_SIZE);
            return keyPairGenerator.generateKeyPair();
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    public static Certificate generateSelfSignedCertificate(KeyPair keyPair, long expirationDate, String comment) {
        return generateSelfSignedCertificate(keyPair, expirationDate, Arrays.asList(Subject.ALL),
                Arrays.asList(Subject.ALL), comment);
    }

    public static Certificate generateSelfSignedCertificate(KeyPair keyPair, long expirationDate,
            List<Subject> subscribePermissions, List<Subject> publishPermissions, String comment) {
        final long serialNumber = secureRandom.get().nextLong();
        final Certificate certificate = new Certificate(Certificate.Type.AUTHORITY, serialNumber, serialNumber,
                expirationDate, keyPair.getPublic(), subscribePermissions, publishPermissions, comment, null);
        return signCertificate(certificate, keyPair.getPrivate(), certificate);
    }

    public static Certificate generateSignedCertificate(Certificate issuer, PrivateKey issuerPrivateKey,
            PublicKey newCertificatePublicKey, Certificate.Type type, long expirationDate,
            List<Subject> subscribePermissions, List<Subject> publishPermissions, String comment) {
        final long serialNumber = secureRandom.get().nextLong();
        final Certificate certificate = new Certificate(type, serialNumber, issuer.getSerialNumber(),
                expirationDate, newCertificatePublicKey, subscribePermissions, publishPermissions, comment, null);
        return signCertificate(issuer, issuerPrivateKey, certificate);
    }

    public static Certificate signCertificate(Certificate issuer, PrivateKey issuerPrivateKey,
            Certificate certificate) {
        if (issuer.getSerialNumber() != certificate.getIssuer()) {
            throw new CertificateIssuerMismatchException(
                    "The authority certificate serial number doesn't much the certificate issuer.");
        }
        validatePermissions(issuer, certificate);
        final byte[] hash = certificate.hash();

        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, issuerPrivateKey);
            final byte[] signature = cipher.doFinal(hash);
            return new Certificate(certificate.getType(), certificate.getSerialNumber(), certificate.getIssuer(),
                    certificate.getExpirationDate(), certificate.getPublicKey(),
                    certificate.getSubscribePermissions(), certificate.getPublishPermissions(),
                    certificate.getComment(), signature);
        } catch (GeneralSecurityException e) {
            throw new CertificateSecurityException(e);
        }
    }

    public static byte[] generateChallenge() {
        final byte[] challenge = new byte[DEFAULT_CHALLENGE_LENGTH];
        secureRandom.get().nextBytes(challenge);
        return challenge;
    }

    public static byte[] signChallenge(PrivateKey key, byte[] challenge, byte[] salt) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            cipher.update(challenge);
            cipher.update(salt);
            return cipher.doFinal();
        } catch (GeneralSecurityException e) {
            throw new CertificateSecurityException(e);
        }
    }

    public static void validateSignature(PublicKey key, byte[] challenge, byte[] salt, byte[] signature) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, key);
            final byte[] decryptedSignature = cipher.doFinal(signature);
            if (decryptedSignature.length != challenge.length + salt.length) {
                throw new InvalidSignatureException("Signature doesn't match challenge");
            }
            for (int i = 0; i < challenge.length; i++) {
                if (decryptedSignature[i] != challenge[i]) {
                    throw new InvalidSignatureException("Signature doesn't match challenge");
                }
            }
            for (int i = 0; i < salt.length; i++) {
                if (decryptedSignature[challenge.length + i] != salt[i]) {
                    throw new InvalidSignatureException("Signature doesn't match challenge");
                }
            }
        } catch (GeneralSecurityException e) {
            throw new CertificateSecurityException(e);
        }
    }

    private CertificateUtils() {
        // Don't instantiate me.
    }

    public static void validatePermissions(Certificate issuer, Certificate certificate) {
        validateSubSubjects(issuer.getPublishPermissions(), certificate.getPublishPermissions(), "publish");
        validateSubSubjects(issuer.getSubscribePermissions(), certificate.getSubscribePermissions(), "subscribe");
    }

    private static void validateSubSubjects(List<Subject> issuerPermissions, List<Subject> permissions,
            String type) {
        outer: for (Subject permission : permissions) {
            for (Subject parentPermission : issuerPermissions) {
                if (parentPermission.isSub(permission)) {
                    continue outer;
                }
            }
            throw new CertificatePermissionError("Permission " + permission + " is not a sub " + type
                    + " permission to any permissions in parent certificate.");
        }
    }

    public static PrivateKey loadPrivateKey(String fileName)
            throws IOException, NoSuchAlgorithmException, InvalidKeySpecException {
        final Path path = Paths.get(fileName);
        final byte[] encodedPrivateKey = Files.readAllBytes(path);
        final KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        final PKCS8EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(encodedPrivateKey);
        return keyFactory.generatePrivate(privateKeySpec);
    }

    public static void savePrivateKey(PrivateKey privateKey, String fileName) throws IOException {
        try (final OutputStream outputStream = Files.newOutputStream(Paths.get(fileName),
                StandardOpenOption.CREATE_NEW)) {
            outputStream.write(privateKey.getEncoded());
        }
    }

    public static TrustStore loadTrustStore(String fileName) throws IOException {
        final TrustStore trustStore = new TrustStore();
        final Path path = Paths.get(fileName);
        if (Files.notExists(path)) {
            return trustStore;
        }
        loadCertificates(path, trustStore);
        return trustStore;
    }

    private static void loadCertificates(Path path, Collection<Certificate> certificates) throws IOException {
        try (final InputStream fileIn = Files.newInputStream(path);
                final InputStream in = new Base64InputStream(fileIn)) {
            CertificateStoreLoader.load(in, certificates);
        }
    }

    /**
     * Loads a collection of certificates as a {@link CertificateChain} from the specified file.
     *
     * @param fileName the file from which the certificates will be loaded
     * @return a certificate chain holding the certificates in the specified file.
     * @throws IOException if an I/O error occurs
     */
    public static CertificateChain loadCertificateChain(String fileName) throws IOException {
        final CertificateChain certificateChain = new CertificateChain();
        final Path path = Paths.get(fileName);
        loadCertificates(path, certificateChain);
        return certificateChain;
    }

    /**
     * Saves a collection of certificates to the specified file.
     *
     * @param fileName the file to which the certificates will be saved
     * @param certificates the certificate to be saved
     * @throws IOException if an I/O error occurs
     */
    public static void saveCertificates(String fileName, Collection<Certificate> certificates) throws IOException {
        final Path path = Paths.get(fileName);
        final Path directory = path.getParent();
        if (directory != null && !Files.exists(directory)) {
            Files.createDirectories(directory);
        }
        try (final OutputStream fileOut = Files.newOutputStream(path, StandardOpenOption.CREATE,
                StandardOpenOption.TRUNCATE_EXISTING); final OutputStream out = new Base64OutputStream(fileOut)) {
            CertificateStoreLoader.store(out, certificates);
        }
    }
}