Dépôt officiel du code source de l'ERP OpenConcerto

/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

 *

 * Copyright 2011 OpenConcerto, by ILM Informatique. All rights reserved.

 *

 * The contents of this file are subject to the terms of the GNU General Public License Version 3

 * only ("GPL"). You may not use this file except in compliance with the License. You can obtain a

 * copy of the License at http://www.gnu.org/licenses/gpl-3.0.html See the License for the specific

 * language governing permissions and limitations under the License.

 *

 * When distributing the software, include this License Header Notice in each file.

 */

 package org.openconcerto.utils;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.security.DigestOutputStream;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

public class MessageDigestUtils {

    private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', };

    /**

     * Turns array of bytes into string representing each byte as unsigned hex number.

     *

     * @param hash Array of bytes to convert to hex-string

     * @return Generated hex string

     */

    public static String asHex(byte hash[]) {

        return toString(hash, HEX_CHARS);

    }

    public static String toString(final byte[] hash, final char[] chars) {

        char buf[] = new char[hash.length * 2];

        for (int i = 0, x = 0; i < hash.length; i++) {

            buf[x++] = chars[(hash[i] >>> 4) & 0xf];

            buf[x++] = chars[hash[i] & 0xf];

        }

        return new String(buf);

    }

    public static byte[] fromHex(String hash) {

        final byte[] buf = new byte[hash.length() / 2];

        for (int i = 0; i < buf.length; i++) {

            buf[i] = (byte) Integer.parseInt(hash.substring(2 * i, 2 * i + 2), 16);

        }

        return buf;

    }

    /**

     * Split an int into 4 bytes.

     *

     * @param integer an int, eg -2^31, or 16.

     * @return the 4 bytes of its two's complement, eg [0x80, 0x00, 0x00, 0x00] or [0x00, 0x00,

     *         0x00, 0x10].

     */

    public static byte[] int2bytes(int integer) {

        final byte[] byteStr = new byte[4];

        byteStr[0] = (byte) (integer >>> 24);

        byteStr[1] = (byte) ((integer >>> 16) & 0xff);

        byteStr[2] = (byte) ((integer >>> 8) & 0xff);

        byteStr[3] = (byte) (integer & 0xff);

        return byteStr;

    }

    /**

     * Cat 4 bytes to make an int.

     *

     * @param buf an array of at least 4 bytes, eg [0x80, 0x00, 0x00, 0x03].

     * @return the resulting int, eg -2^31 + 3 or -2147483645.

     */

    public static int bytes2int(byte[] buf) {

        // eg -128 == 10000000 promoted to int => 11...110000000

        // so we need & 0xff to remove added ones (except for the 1st since they're all shifted

        // away)

        return (buf[0] << 24) | ((buf[1] & 0xff) << 16) | ((buf[2] & 0xff) << 8) | (buf[3] & 0xff);

    }

    public static String getHashString(MessageDigest md) {

        return asHex(md.digest());

    }

    public static String getHashString(String algo, byte[] data) throws NoSuchAlgorithmException {

        final MessageDigest md = MessageDigest.getInstance(algo);

        return getHashString(md, data);

    }

    public static String getHashString(MessageDigest md, byte[] data) {

        md.update(data);

        return getHashString(md);

    }

    public static String getHashString(MessageDigest md, final InputStream ins) throws IOException {

        return asHex(getHash(md, ins));

    }

    public static byte[] getHash(MessageDigest md, final InputStream ins) throws IOException {

        return getHash(md, ins, StreamUtils.NULL_OS);

    }

    public static byte[] getHash(MessageDigest md, final InputStream ins, final OutputStream out) throws IOException {

        try (final DigestOutputStream digestStream = new DigestOutputStream(out, md)) {

            StreamUtils.copy(ins, digestStream);

        }

        return md.digest();

    }

    public static byte[] getHash(MessageDigest md, final File f) throws IOException {

        try (final InputStream ins = new FileInputStream(f)) {

            return getHash(md, ins);

        }

    }

    public static String getMD5(File f) throws IOException {

        return asHex(getHash(getMD5(), f));

    }

    public static MessageDigest getMD5() {

        try {

            return MessageDigest.getInstance("MD5");

        } catch (NoSuchAlgorithmException e) {

            throw new IllegalStateException("MD5 is part of the standard JRE", e);

        }

    }

    public static MessageDigest getSHA256() {

        try {

            return MessageDigest.getInstance("SHA-256");

        } catch (NoSuchAlgorithmException e) {

            throw new IllegalStateException("SHA-256 is part of the standard JRE", e);

        }

    }

    private MessageDigestUtils() {

    }

}