# CryptFilter.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You 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 org.apache.pdfbox.filter;

    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;

    import org.apache.pdfbox.cos.COSDictionary;
    import org.apache.pdfbox.cos.COSName;

    /**
     * Decrypts data encrypted by a security handler, reproducing the data as it was before encryption.
     * @author Adam Nichols
     */
    final class CryptFilter extends Filter
    {
        @Override
        public DecodeResult decode(InputStream encoded, OutputStream decoded,
                                             COSDictionary parameters, int index) throws IOException
        {
            COSName encryptionName = parameters.getCOSName(COSName.NAME);
            if(encryptionName == null || encryptionName.equals(COSName.IDENTITY))
            {
                // currently the only supported implementation is the Identity crypt filter
                Filter identityFilter = new IdentityFilter();
                identityFilter.decode(encoded, decoded, parameters, index);
                return new DecodeResult(parameters);
            }
            throw new IOException("Unsupported crypt filter " + encryptionName.getName());
        }

        @Override
        protected void encode(InputStream input, OutputStream encoded, COSDictionary parameters)
                throws IOException
        {
            COSName encryptionName = parameters.getCOSName(COSName.NAME);
            if(encryptionName == null || encryptionName.equals(COSName.IDENTITY))
            {
                // currently the only supported implementation is the Identity crypt filter
                Filter identityFilter = new IdentityFilter();
                identityFilter.encode(input, encoded, parameters);
            }
            else
            {
                throw new IOException("Unsupported crypt filter " + encryptionName.getName());
            }
        }
    }