de.schlichtherle.truezip.zip.WinZipAesUtils Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of truezip-driver-zip Show documentation

The file system driver family for ZIP and related archive file types. Add the JAR artifact of this module to the run time class path to make its file system drivers available for service location in the client API modules.

There is a newer version: 7.7.10

Show newest version

/*
 * Copyright (C) 2005-2013 Schlichtherle IT Services.
 * All rights reserved. Use is subject to license terms.
 */
package de.schlichtherle.truezip.zip;

import de.schlichtherle.truezip.crypto.param.AesKeyStrength;

/**
 * Static utility methods for WinZip AES encryption.
 * 
 * @author  Christian Schlichtherle
 */
final class WinZipAesUtils {

    /** You cannot instantiate this class. */
    private WinZipAesUtils() {
    }

    /** 
     * Returns the overhead in bytes which is added to each WinZip AES
     * encrypted entry.
     * 
     * @param  keyStrength The AES key strength.
     * @return the overhead in bytes which is added to each WinZip AES
     *         encrypted entry.
     */
    static int overhead(AesKeyStrength keyStrength) {
        return keyStrength.getBytes() / 2 // salt value
                + 2   // password verification value
                + 10; // authentication code
    }
}