HashUtility.java

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/*
 * Autopsy Forensic Browser
 *
 * Copyright 2011 Basis Technology Corp.
 * Contact: carrier <at> sleuthkit <dot> org
 *
 * 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 org.sleuthkit.datamodel;

import java.io.IOException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.io.InputStream;

public class HashUtility {

        private final static int BUFFER_SIZE = 16 * 1024;

        static public String calculateMd5(AbstractFile file) throws IOException {
                String hashText = "";
                InputStream in = new ReadContentInputStream(file);
                Logger logger = Logger.getLogger(HashUtility.class.getName());
                try {
                        byte[] buffer = new byte[BUFFER_SIZE];
                        MessageDigest md = MessageDigest.getInstance("md5"); //NON-NLS
                        int len = in.read(buffer);
                        while (len != -1) {
                                md.update(buffer, 0, len);
                                len = in.read(buffer);
                        }
                        byte[] hash = md.digest();
                        BigInteger bigInt = new BigInteger(1, hash);
                        hashText = bigInt.toString(16);
                        // zero padding
                        while (hashText.length() < 32) {
                                hashText = "0" + hashText;
                        }
                        file.getSleuthkitCase().setMd5Hash(file, hashText);
                } catch (NoSuchAlgorithmException ex) {
                        logger.log(Level.WARNING, "No algorithm known as 'md5'", ex); //NON-NLS
                } catch (TskCoreException ex) {
                        logger.log(Level.WARNING, "Error updating content's md5 in database", ex); //NON-NLS
                } finally {
                        in.close();
                }
                return hashText;
        }

        public static boolean isNoDataMd5(String md5) {
                return md5.toLowerCase().equals("d41d8cd98f00b204e9800998ecf8427e"); //NON-NLS
        }
}