net.nicholaswilliams.java.licensing.encryption.FilePrivateKeyDataProvider.java Source code

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Here is the source code for net.nicholaswilliams.java.licensing.encryption.FilePrivateKeyDataProvider.java

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/*
 * FilePrivateKeyDataProvider.java from LicenseManager modified Thursday, January 24, 2013 16:41:55 CST (-0600).
 *
 * Copyright 2010-2013 the original author or authors.
 *
 * 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 net.nicholaswilliams.java.licensing.encryption;

import net.nicholaswilliams.java.licensing.exception.KeyNotFoundException;
import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * A default implementation of {@link PrivateKeyDataProvider} that reads the private key from a file.<br />
 * <br />
 * This provider is immutable. Once created, the file that the private key is located at cannot be changed.
 *
 * @author Nick Williams
 * @version 1.0.0
 * @since 1.0.0
 */
public class FilePrivateKeyDataProvider implements PrivateKeyDataProvider {
    private final File privateKeyFile;

    /**
     * Create a new provider, specifying the file from which the private key can be read.
     *
     * @param privateKeyFile the private key file
     */
    public FilePrivateKeyDataProvider(File privateKeyFile) {
        this.privateKeyFile = privateKeyFile.getAbsoluteFile();
    }

    /**
     * Create a new provider, specifying the name of the file from which the private key can be read.
     *
     * @param privateKeyFileName The private key file name
     */
    public FilePrivateKeyDataProvider(String privateKeyFileName) {
        this.privateKeyFile = new File(privateKeyFileName).getAbsoluteFile();
    }

    /**
     * This method returns the data from the file containing the encrypted
     * private key from the public/private key pair. The contract for this
     * method can be fulfilled by storing the data in a byte array literal
     * in the source code itself.<br/>
     * <br/>
     * It is <em>imperative</em> that you obfuscate the bytecode for the
     * implementation of this class. It is also imperative that the byte
     * array exist only for the life of this method (i.e., DO NOT store it as
     * an instance or class field).
     *
     * @return the encrypted file contents from the private key file.
     * @throws net.nicholaswilliams.java.licensing.exception.KeyNotFoundException if the key data could not be retrieved; an acceptable message or chained cause must be provided.
     */
    @Override
    public byte[] getEncryptedPrivateKeyData() throws KeyNotFoundException {
        try {
            return FileUtils.readFileToByteArray(this.privateKeyFile);
        } catch (FileNotFoundException e) {
            throw new KeyNotFoundException(
                    "The private key file [" + this.privateKeyFile.getPath() + "] does not exist.");
        } catch (IOException e) {
            throw new KeyNotFoundException(
                    "Could not read from the private key file [" + this.privateKeyFile.getPath() + "].", e);
        }
    }

    /**
     * Gets the file that the private key is located at.
     *
     * @return the file.
     */
    public File getPrivateKeyFile() {
        return this.privateKeyFile;
    }
}