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/*******************************************************************************
* Copyright (c) 2010-2014, Miklos Foldenyi, Andras Szabolcs Nagy, Abel Hegedus, Akos Horvath, Zoltan Ujhelyi and Daniel Varro
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-v20.html.
*
* SPDX-License-Identifier: EPL-2.0
*******************************************************************************/
package org.eclipse.viatra.dse.util;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.eclipse.viatra.dse.api.DSEException;
/**
* Utility class that encapsulates a {@link MessageDigest} instance to aid calculating hash values more easily, and to
* reuse a {@link MessageDigest} instance.
*
*/
public final class Hasher {
private MessageDigest md;
private static final int HEX = 16;
private Hasher(MessageDigest md) {
this.md = md;
}
/**
* Calculates and returns a hash value.
*
* @param data
* the data to be hashed in a {@link String}.
* @return the hash value in some {@link String} representation.
*/
public String hash(String data) {
md.update(data.getBytes(), 0, data.length());
return new String(md.digest());
}
@SuppressWarnings("unused")
private String alternateHashBest(String data) {
md.update(data.getBytes(), 0, data.length());
return new String(md.digest());
}
@SuppressWarnings("unused")
private String alternateHashSecondBest(String data) {
md.update(data.getBytes(), 0, data.length());
return new BigInteger(1, md.digest()).toString(HEX);
}
@SuppressWarnings("unused")
private String alternateHashThirdBest(String data) {
md.update(data.getBytes(), 0, data.length());
byte[] array = md.digest();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < array.length; i++) {
sb.append(Integer.toHexString((int) array[i]));
}
return sb.toString();
}
/**
* Returns a {@link Hasher} with an internal {@link MessageDigest} that is based on the protocol named
* {@code protocoll}.
*
* @param protocoll
* the name of the hash algorythm.
* @return the initialized {@link Hasher}
*
* @throws DSEException
* on initialization failure.
*/
public static Hasher getHasher(String protocoll) {
try {
return new Hasher(MessageDigest.getInstance(protocoll));
} catch (NoSuchAlgorithmException e) {
throw new DSEException(e);
}
}
public static final String SHA1_PROTOCOLL = "SHA-1";
}
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