InMemoryKeyStore.java

/*
 * Copyright 2014 individual contributors as indicated by the @author 
 * tags
 * 
 * This is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this software.  If not, see <http://www.gnu.org/licenses/>. 
 */

package org.sector67.otp.key;

import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;

/**
 * An in-memory implementation of an OTP keystore primarily for testing purposes
 * 
 * @author scott.hasse@gmail.com
 */
public class InMemoryKeyStore implements TestableKeyStore {

	private Map<String, Integer> offsets = new HashMap<String, Integer>();
	private Map<String, byte[]> keys = new HashMap<String, byte[]>();
	Random r = new SecureRandom();
	private KeyEraser eraser = new MultiPassSecureRandomEraser();

	@Override
	public void init() {

	}

	@Override
	public void setKeyEraser(KeyEraser eraser) {
		this.eraser = eraser;
	}

	public void generateKey(String name, int length) {
		if (name == null) {
			throw new IllegalArgumentException(
					"You cannot create a null key name.");
		}
		if (keys.containsKey(name)) {
			throw new IllegalArgumentException(
					"You cannot create a key that already exists: " + name);
		}
		offsets.put(name, new Integer(0));
		byte[] key = new byte[length];
		r.nextBytes(key);
		keys.put(name, key);
	}

	/*
	 * Put a key in the key store, for testing purposes
	 */
	public void addKey(String name, byte[] key, int offset) {
		if (name == null || key == null) {
			throw new IllegalArgumentException(
					"You cannot create a null key name.");
		}
		if (keys.containsKey(name)) {
			throw new IllegalArgumentException(
					"You cannot create a key that already exists: " + name);
		}
		offsets.put(name, new Integer(offset));
		keys.put(name, Arrays.copyOf(key, key.length));
	}

	/*
	 * Provides the next bytes from the key and updates the current key offset
	 */
	@Override
	public byte[] getKeyBytesForEncryption(String name, int length)
			throws KeyException {
		if (name == null) {
			throw new KeyException("You cannot use a null key name.");
		}
		if (!keys.containsKey(name)) {
			throw new KeyException(
					"The requested key does not exist in this key store: "
							+ name);
		}
		byte[] key = keys.get(name);
		int currentOffset = offsets.get(name);
		if (key.length < currentOffset + length) {
			throw new KeyException(
					"The key is not long enough to provide the requested bytes");
		}
		byte[] result = new byte[length];
		for (int i = 0; i < length; i++) {
			result[i] = key[currentOffset + i];
		}
		// update the offset
		offsets.put(name, currentOffset + length);
		return result;
	}

	public Set<String> getKeyNames() {
		return keys.keySet();
	}

	public void copyKey(String source, String destination) {
		byte[] key = keys.get(source);
		byte[] copy = Arrays.copyOf(key, key.length);
		int offset = offsets.get(source);
		offsets.put(destination, offset);
		keys.put(destination, copy);
	}

	public class InMemoryKeyData implements KeyData {
		private int position = 0;
		private byte[] key;

		public InMemoryKeyData(byte[] key) {
			this.key = key;
			this.position = 0;
		}

		public void close() {
			// no-op for in-memory
		}

		public void seek(int position) throws KeyException {
			this.position = position;

		}

		public void write(byte[] data) throws KeyException {
			// System.out.println("data length: " + data.length + " position: "
			// + position);
			for (int i = 0; i < data.length; i++) {
				key[position + i] = data[position];
			}
		}

		public byte[] getBytes() throws KeyException {
			return key;
		}

	}

	@Override
	public List<String> listKeys() {
		List<String> result = new ArrayList<String>();
		result.addAll(keys.keySet());
		Collections.sort(result);
		return result;
	}

	@Override
	public void deleteKey(String name) {
		if (offsets.containsKey(name)) {
			offsets.remove(name);
		}
		if (keys.containsKey(name)) {
			keys.remove(name);
		}

	}

	@Override
	public int getCurrentOffset(String keyName) throws KeyException {
		return offsets.get(keyName);
	}

	@Override
	public int getSize(String keyName) throws KeyException {
		throw new UnsupportedOperationException("Not Yet Implemented");
	}

	@Override
	public byte[] getKeyBytesForDecryption(String name, int offset, int length)
			throws KeyException {
		if (name == null) {
			throw new KeyException("You cannot use a null key name.");
		}
		if (!keys.containsKey(name)) {
			throw new KeyException(
					"The requested key does not exist in this key store: "
							+ name);
		}
		byte[] key = keys.get(name);
		int currentOffset = offset;
		if (key.length < currentOffset + length) {
			throw new KeyException(
					"The key is not long enough to provide the requested bytes");
		}
		byte[] result = new byte[length];
		for (int i = 0; i < length; i++) {
			result[i] = key[currentOffset + i];
		}
		return result;
	}

	@Override
	public void eraseKeyBytes(String name, int offset, int length)
			throws KeyException {
		if (name == null) {
			throw new KeyException("You cannot use a null key name.");
		}
		if (!keys.containsKey(name)) {
			throw new KeyException(
					"The requested key does not exist in this key store: "
							+ name);
		}
		byte[] key = keys.get(name);
		int currentOffset = offset;
		if (key.length < currentOffset + length) {
			throw new KeyException(
					"The key is not long enough to provide the requested bytes");
		}
		InMemoryKeyData kd = new InMemoryKeyData(key);
		eraser.erase(kd, offset, length);
		keys.put(name, kd.getBytes());

	}
}