de.schlichtherle.key.PromptingAesKeyProvider Maven / Gradle / Ivy

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TrueZIP is a Java based Virtual File System (VFS) to enable transparent, multi-threaded read/write access to archive files (ZIP, TAR etc.) as if they were directories. Archive files may be arbitrarily nested and the nesting level is only limited by heap and file system size.

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/*
 * Copyright (C) 2006-2010 Schlichtherle IT Services
 *
 * 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 de.schlichtherle.key;

/**
 * An implementation of {@link AesKeyProvider} which prompts the user for
 * a key and allows to select the cipher key strength when creating a new
 * AES encrypted resource or replacing the entire contents of an already
 * existing AES encrypted resource.
 * 
 * This class is thread safe.
 *
 * @author Christian Schlichtherle
 * @version $Id$
 * @since TrueZIP 6.0
 */
public class PromptingAesKeyProvider
        extends PromptingKeyProvider
        implements AesKeyProvider {

    private int keyStrength = KEY_STRENGTH_256;

    public int getKeyStrength() {
        assert keyStrength == KEY_STRENGTH_128
                || keyStrength == KEY_STRENGTH_192
                || keyStrength == KEY_STRENGTH_256;
        return keyStrength;
    }

    public void setKeyStrength(int keyStrength) {
        if (keyStrength != KEY_STRENGTH_128
                && keyStrength != KEY_STRENGTH_192
                && keyStrength != KEY_STRENGTH_256)
            throw new IllegalArgumentException();
        this.keyStrength = keyStrength;
    }

    protected String getUIClassID() {
        return "PromptingAesKeyProvider";
    }

    /**
     * Resets the key strength to 256 bits.
     */
    protected void onReset() {
        keyStrength = KEY_STRENGTH_256;
    }

    /**
     * Returns the current key strength.
     */
    public String toString() {
        return "" + (128 + keyStrength * 64);
    }
}