de.schlichtherle.key.AesKeyProvider 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;

/**
 * A {@link KeyProvider} which 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.
 * The cipher key strength for the AES encryption may be either 128, 192 or
 * 256 bits.
 *
 * @author Christian Schlichtherle
 * @version $Id$
 * @since TrueZIP 6.1
 */
public interface AesKeyProvider extends KeyProvider {

    /** Identifier for a 128 bit ciphering key. */
    int KEY_STRENGTH_128 = 0;

    /** Identifier for a 192 bit ciphering key. */
    int KEY_STRENGTH_192 = 1;

    /** Identifier for a 256 bit ciphering key. */
    int KEY_STRENGTH_256 = 2;

    /**
     * Returns the cipher key strength for the AES encryption.
     * 
     * @return One of {@code KEY_STRENGTH_128},
     *        {@code KEY_STRENGTH_192} or {@code KEY_STRENGTH_256}.
     */
    int getKeyStrength();

    /**
     * Sets the cipher key strength for the AES encryption.
     * 
     * @param keyStrength One of {@code KEY_STRENGTH_128},
     *        {@code KEY_STRENGTH_192} or {@code KEY_STRENGTH_256}.
     * @throws IllegalArgumentException If the preconditions for the parameter
     *         do not hold.
     */
    void setKeyStrength(int keyStrength);
}