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/*
* Copyright (c) 2012, intarsys consulting GmbH
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* - Neither the name of intarsys nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package de.intarsys.tools.crypto;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import de.intarsys.tools.authenticate.PasswordTools;
import de.intarsys.tools.collection.ByteArrayTools;
/**
* A memory holding secret values. Goal is to have "visible" secrets only at the
* API of the store. Within the store the data is encrypted to doom memory
* inspection..
*
* For this strategy to be successful, its very important for clients to zero
* out secrets that are no longer used.
*
* The memory itself is based on opaque handles - this way no client can
* enumerate or guess content of this memory - as long as the owner keeps its
* handle private.
*
*/
public class SecretMemory {
private static ICryptdec createSessionCryptdec() {
char[] passPhrase = null;
byte[] salt = null;
byte[] iv = null;
try {
passPhrase = PasswordTools.createPassword(16);
salt = ByteArrayTools.createRandomBytes(8);
iv = ByteArrayTools.createRandomBytes(16);
return new PBAES128Cryptdec("session", iv, passPhrase, salt, 19);
} catch (Exception e) {
throw new IllegalStateException("cryptec initialization error", e);
} finally {
Arrays.fill(passPhrase, ' ');
Arrays.fill(salt, (byte) 0x00);
Arrays.fill(iv, (byte) 0x00);
}
}
final transient private ICryptdec cryptdec;
final transient private Map memory = new HashMap();
public SecretMemory() {
this(createSessionCryptdec());
}
public SecretMemory(ICryptdec cryptdec) {
super();
this.cryptdec = cryptdec;
}
public void clear() {
memory.clear();
}
public byte[] getBytes(Object key) throws IOException {
byte[] crypted = memory.get(key);
if (crypted == null) {
return null;
}
byte[] decrypted = cryptdec.decrypt(crypted);
return decrypted;
}
public char[] getCharacters(Object key) throws IOException {
byte[] crypted = memory.get(key);
if (crypted == null) {
return null;
}
byte[] decrypted = cryptdec.decrypt(crypted);
char[] secret = new char[decrypted.length / 2];
int k = 0;
for (int i = 0; i < secret.length; i++) {
char c = (char) (((decrypted[k++] & 0xff) << 8) + (decrypted[k++] & 0xff));
secret[i] = c;
}
return secret;
}
public Object put(byte[] secret) throws IOException {
byte[] crypted = cryptdec.encrypt(secret);
Object key = new Object();
memory.put(key, crypted);
return key;
}
public Object put(char[] secret) throws IOException {
byte[] bytes = new byte[secret.length * 2];
int k = 0;
for (int i = 0; i < secret.length; i++) {
char c = secret[i];
bytes[k++] = (byte) (c >> 8);
bytes[k++] = (byte) c;
}
byte[] crypted = cryptdec.encrypt(bytes);
Object key = new Object();
memory.put(key, crypted);
return key;
}
public void remove(Object key) {
memory.remove(key);
}
}