iaik.utils

Class CipherOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

iaik.utils.CipherOutputStream

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable

public class CipherOutputStream
extends java.io.FilterOutputStream

Class for en/decrypting data to be written to an output stream.

This class extends the java.io.FilterOutputStream class for combining the functionality of a OutputStream and a Cipher. According to the operation mode the Cipher has been initialized with, data is en/decrypted before writing it to the underlying stream when calling one of the write() methods.

This class works similar than javax.crypto.CipherOutputStream except for that method close() throws an (IO)Exception when internally calling cipher.doFinal() causes an Exception (whereas javax.crypto.CipherOutputStream does not throw an exception of cipher.doFinal fails.

Version:

File Revision 15

See Also:

OutputStream, FilterOutputStream, Cipher, CipherInputStream

Field Summary

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor and Description
CipherOutputStream(java.io.OutputStream os) Creates a CipherOutputStream only from an OutputStream.
CipherOutputStream(java.io.OutputStream os, javax.crypto.Cipher cipher) Creates a CipherOutputStream using an OutputStream and a Cipher initialized either for encryption or decryption.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Calls the cipher for the last time and closes the output stream.
void	write(byte[] b) Writes the bytes from the given byte array to this output stream.
void	write(byte[] b, int off, int len) Writes a specified number of bytes from a given position of the given byte array to this output stream.
void	write(int b) Writes a byte to the underlying output stream.

Methods inherited from class java.io.FilterOutputStream

flush

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CipherOutputStream

public CipherOutputStream(java.io.OutputStream os,
                  javax.crypto.Cipher cipher)

Creates a CipherOutputStream using an OutputStream and a Cipher initialized either for encryption or decryption.

Parameters:

os - the output stream.

cipher - an initialized cipher.

CipherOutputStream

public CipherOutputStream(java.io.OutputStream os)

Creates a CipherOutputStream only from an OutputStream. Since no Cipher is specified, alternatively you may create a CipherOutputStream using an OutputStream and a NullCipher.

Parameters:

os - the output stream

Method Detail

write

public void write(int b)
           throws java.io.IOException

Writes a byte to the underlying output stream. Depending on whether the supplied Cipher has been initialized for encryption or decryption, the given byte is processed accordingly before writing it to the stream.

Overrides:

write in class java.io.FilterOutputStream

Parameters:

b - the byte to be written to this stream

Throws:

java.io.IOException - if an I/O error occurs

write

public void write(byte[] b)
           throws java.io.IOException

Writes the bytes from the given byte array to this output stream. Depending on whether the supplied Cipher has been initialized for encryption or decryption, the bytes are processed accordingly before writing it to the stream.

Overrides:

write in class java.io.FilterOutputStream

Parameters:

b - the byte array containing the data to be written to this stream

Throws:

java.io.IOException - if an I/O error occurs.

write

public void write(byte[] b,
         int off,
         int len)
           throws java.io.IOException

Writes a specified number of bytes from a given position of the given byte array to this output stream. Depending on whether the supplied Cipher has been initialized for encryption or decryption, the bytes are processed accordingly before writing it to the stream.

Overrides:

write in class java.io.FilterOutputStream

Parameters:

b - the byte array containing the data to be written to this stream

off - the start offset indicating the position within the given byte array b from which the data is to be taken for en/decrypting and writing it to the stream

len - the number of bytes to write this stream

Throws:

java.io.IOException - if an I/O error occurs

close

public void close()
           throws java.io.IOException

Calls the cipher for the last time and closes the output stream. Always call close() on a CipherOutputStream because this method calls doFinal(), which appends/removes the padding, on the crypted data.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class java.io.FilterOutputStream

Throws:

java.io.IOException - if an I/O error occurs