| /* ==================================================================== |
| 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.poi.poifs.crypt.cryptoapi; |
| |
| import java.io.ByteArrayInputStream; |
| import java.security.GeneralSecurityException; |
| |
| import javax.crypto.Cipher; |
| import javax.crypto.ShortBufferException; |
| |
| import org.apache.poi.EncryptedDocumentException; |
| import org.apache.poi.util.Internal; |
| |
| /** |
| * A seekable InputStream, which is used to decrypt/extract the document entries |
| * within the encrypted stream |
| */ |
| @Internal |
| /* package */ class CryptoAPIDocumentInputStream extends ByteArrayInputStream { |
| private Cipher cipher; |
| private final CryptoAPIDecryptor decryptor; |
| private byte oneByte[] = { 0 }; |
| |
| public void seek(int newpos) { |
| if (newpos > count) { |
| throw new ArrayIndexOutOfBoundsException(newpos); |
| } |
| |
| this.pos = newpos; |
| mark = newpos; |
| } |
| |
| public void setBlock(int block) throws GeneralSecurityException { |
| cipher = decryptor.initCipherForBlock(cipher, block); |
| } |
| |
| @Override |
| public synchronized int read() { |
| int ch = super.read(); |
| if (ch == -1) { |
| return -1; |
| } |
| oneByte[0] = (byte) ch; |
| try { |
| cipher.update(oneByte, 0, 1, oneByte); |
| } catch (ShortBufferException e) { |
| throw new EncryptedDocumentException(e); |
| } |
| return oneByte[0]; |
| } |
| |
| @Override |
| public synchronized int read(byte b[], int off, int len) { |
| int readLen = super.read(b, off, len); |
| if (readLen ==-1) { |
| return -1; |
| } |
| try { |
| cipher.update(b, off, readLen, b, off); |
| } catch (ShortBufferException e) { |
| throw new EncryptedDocumentException(e); |
| } |
| return readLen; |
| } |
| |
| public CryptoAPIDocumentInputStream(CryptoAPIDecryptor decryptor, byte buf[]) |
| throws GeneralSecurityException { |
| super(buf); |
| this.decryptor = decryptor; |
| cipher = decryptor.initCipherForBlock(null, 0); |
| } |
| } |