001/* CipherOutputStream.java -- Filters output through a cipher. 002 Copyright (C) 2004 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package javax.crypto; 040 041import java.io.FilterOutputStream; 042import java.io.IOException; 043import java.io.OutputStream; 044 045/** 046 * A filtered output stream that transforms data written to it with a 047 * {@link Cipher} before sending it to the underlying output stream. 048 * 049 * @author Casey Marshall (csm@gnu.org) 050 */ 051public class CipherOutputStream extends FilterOutputStream 052{ 053 /** The underlying cipher. */ 054 private Cipher cipher; 055 056 /** 057 * Create a new cipher output stream. The cipher argument must have already 058 * been initialized. 059 * 060 * @param out The sink for transformed data. 061 * @param cipher The cipher to transform data with. 062 */ 063 public CipherOutputStream(OutputStream out, Cipher cipher) 064 { 065 super(out); 066 this.cipher = (cipher != null) ? cipher : new NullCipher(); 067 } 068 069 /** 070 * Create a cipher output stream with no cipher. 071 * 072 * @param out The sink for transformed data. 073 */ 074 protected CipherOutputStream(OutputStream out) 075 { 076 super(out); 077 } 078 079 /** 080 * Close this output stream, and the sink output stream. 081 * <p> 082 * This method will first invoke the {@link Cipher#doFinal()} method of the 083 * underlying {@link Cipher}, and writes the output of that method to the 084 * sink output stream. 085 * 086 * @throws IOException If an I/O error occurs, or if an error is caused by 087 * finalizing the transformation. 088 */ 089 public void close() throws IOException 090 { 091 try 092 { 093 out.write(cipher.doFinal()); 094 out.flush(); 095 out.close(); 096 } 097 catch (Exception cause) 098 { 099 IOException ioex = new IOException(String.valueOf(cause)); 100 ioex.initCause(cause); 101 throw ioex; 102 } 103 } 104 105 /** 106 * Flush any pending output. 107 * 108 * @throws IOException If an I/O error occurs. 109 */ 110 public void flush() throws IOException 111 { 112 out.flush(); 113 } 114 115 /** 116 * Write a single byte to the output stream. 117 * 118 * @param b The next byte. 119 * @throws IOException If an I/O error occurs, or if the underlying cipher is 120 * not in the correct state to transform data. 121 */ 122 public void write(int b) throws IOException 123 { 124 write(new byte[] { (byte) b }, 0, 1); 125 } 126 127 /** 128 * Write a byte array to the output stream. 129 * 130 * @param buf The next bytes. 131 * @throws IOException If an I/O error occurs, or if the underlying cipher is 132 * not in the correct state to transform data. 133 */ 134 public void write(byte[] buf) throws IOException 135 { 136 write(buf, 0, buf.length); 137 } 138 139 /** 140 * Write a portion of a byte array to the output stream. 141 * 142 * @param buf The next bytes. 143 * @param off The offset in the byte array to start. 144 * @param len The number of bytes to write. 145 * @throws IOException If an I/O error occurs, or if the underlying cipher is 146 * not in the correct state to transform data. 147 */ 148 public void write(byte[] buf, int off, int len) throws IOException 149 { 150 byte[] b = cipher.update(buf, off, len); 151 if (b != null) 152 out.write(b); 153 } 154}