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/*
* Copyright (c) 2017, Virgil Security, Inc.
*
* All rights reserved.
* 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 virgil 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 HOLDER 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 com.virgilsecurity.sdk.pfs;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import com.virgilsecurity.crypto.VirgilHash;
import com.virgilsecurity.crypto.VirgilHash.Algorithm;
import com.virgilsecurity.sdk.exception.NullArgumentException;
import com.virgilsecurity.sdk.utils.ConvertionUtils;
/**
* @author Andrii Iakovenko
*
*/
public class Fingerpint {
private static final int ITERATIONS = 4096;
/**
* Calculate fingerprint for card identifiers.
*
* @param cardsIds
* the card identifiers.
* @return the fingerprint as a string.
*/
public static String calculateFingerprint(List cardsIds) {
List sortedCardsIds = new ArrayList<>();
if (cardsIds != null) {
sortedCardsIds.addAll(cardsIds);
}
Collections.sort(sortedCardsIds);
byte[] cardsData = null;
try (ByteArrayOutputStream os = new ByteArrayOutputStream()) {
for (String cardId : sortedCardsIds) {
os.write(ConvertionUtils.toBytes(cardId));
}
cardsData = os.toByteArray();
} catch (IOException e) {
// Nothing to do
}
byte[] previousHash = null;
try (VirgilHash hash = new VirgilHash(Algorithm.SHA384)) {
for (int i = 0; i < ITERATIONS; i++) {
if (previousHash == null) {
previousHash = hash.hash(cardsData);
} else {
byte[] data = new byte[cardsData.length + previousHash.length];
System.arraycopy(cardsData, 0, data, 0, cardsData.length);
System.arraycopy(previousHash, 0, data, cardsData.length, previousHash.length);
previousHash = hash.hash(data);
}
}
}
return hashToStr(previousHash);
}
private static String hashToStr(byte[] hash) {
if (hash == null) {
throw new NullArgumentException("hash");
}
if (hash.length != 48) {
throw new IllegalArgumentException("Invalid hash length.");
}
StringBuilder res = new StringBuilder();
for (int index = 0; index < hash.length; index += 4) {
int endIndex = index + 4;
ByteBuffer buffer = ByteBuffer.wrap(Arrays.copyOfRange(hash, index, endIndex));
buffer.order(ByteOrder.LITTLE_ENDIAN);
long num = Integer.toUnsignedLong(buffer.getInt());
num = Long.remainderUnsigned(num, 100000);
res.append(String.format("%05d ", num));
}
return res.substring(0, res.length() - 1);
}
}
