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/*
* Copyright 2013 The Android Open Source Project
*
* 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 javax.crypto.spec;
import java.security.spec.AlgorithmParameterSpec;
import java.util.Arrays;
/**
* Provides a the parameters for an instance of a {@link javax.crypto.Cipher}
* using Galois/Counter Mode (GCM). This is an Authenticated Encryption with
* Associated Data (AEAD) mode for a cipher which allows you to use the
* {@link javax.crypto.Cipher#updateAAD(byte[])} method to provide data that is
* transmitted in the clear but authenticated using a cryptographic Message
* Authentication Code (MAC).
*
* @since 1.7
*/
public class GCMParameterSpec implements AlgorithmParameterSpec {
private final int tagLen;
private final byte[] iv;
/**
* Creates a new {@code GCMParameterSpec} instance from the specified
* Initial Vector (IV) from buffer {@code iv} and a tag length of
* {@code tagLen} in bits.
*
* @throws IllegalArgumentException if the specified {@code iv} is null or
* {@code offset} and {@code byteCount} do not specify a valid
* chunk in the specified buffer.
*/
public GCMParameterSpec(int tagLen, byte[] iv) {
if (tagLen < 0) {
throw new IllegalArgumentException("tag should be a non-negative integer");
}
if (iv == null) {
throw new IllegalArgumentException("iv == null");
}
this.tagLen = tagLen;
this.iv = iv.clone();
}
/**
* Creates a new {@code GCMParameterSpec} instance with the Initial Vector
* (IV) of {@code byteCount} bytes from the specified buffer {@code iv}
* starting at {@code offset} and a tag length of {@code tagLen} in bits.
*
* @throws IllegalArgumentException if the specified {@code iv} is null or
* {@code offset} and {@code byteCount} do not specify a valid
* chunk in the specified buffer.
* @throws ArrayIndexOutOfBoundsException if {@code offset} or
* {@code byteCount} are negative.
*/
public GCMParameterSpec(int tagLen, byte[] iv, int offset, int byteCount) {
if (tagLen < 0) {
throw new IllegalArgumentException("tag should be a non-negative integer");
}
if (iv == null) {
throw new IllegalArgumentException("iv == null");
}
try {
Arrays.checkOffsetAndCount(iv.length, offset, byteCount);
} catch (ArrayIndexOutOfBoundsException e) {
throw new IllegalArgumentException(e);
}
this.tagLen = tagLen;
this.iv = Arrays.copyOfRange(iv, offset, offset + byteCount);
}
/**
* Returns the size of the tag in bits.
*/
public int getTLen() {
return tagLen;
}
/**
* Returns the Initial Vector (IV) used by this parameter spec.
*/
public byte[] getIV() {
return iv.clone();
}
}
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