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Class javax.crypto.CipherOutputStream

java.lang.Object
    |
    +----java.io.OutputStream
            |
            +----java.io.FilterOutputStream
                    |
                    +----javax.crypto.CipherOutputStream

public class CipherOutputStream
extends java.io.FilterOutputStream
A CipherOutputStream is composed of an OutputStream and a Cipher so that write() methods first process the data before writing them out to the underlying OutputStream. The Cipher must be fully initialized before being used by a CipherOutputStream.

For example, if the Cipher is initialized for encryption, the CipherOutputStream will attempt to encrypt data before writing out the encrypted data.

This class adheres strictly to the semantics, especially the failure semantics, of its ancestor classes java.io.OutputStream and java.io.FilterOutputStream. This class has exactly those methods specified in its ancestor classes, and overrides them all. Moreover, this class catches all exceptions that are not thrown by its ancestor classes.

It is crucial for a programmer using this class not to use methods that are not defined or overriden in this class (such as a new method or constructor that is later added to one of the super classes), because the design and implementation of those methods are unlikely to have considered security impact with regard to CipherOutputStream.

Since:
JCE1.2
See Also:
java.io.OutputStream, java.io.FilterOutputStream, Cipher, CipherInputStream

Fields inherited from class java.io.FilterOutputStream
 out
 

Constructor Summary
 CipherOutputStream(java.io.OutputStream os, Cipher c)
Constructs a CipherOutputStream from an OutputStream and a Cipher.
 CipherOutputStream(java.io.OutputStream os)
Constructs a CipherOutputStream from an OutputStream without specifying a Cipher.
 

Method Summary
void  close()
Closes this output stream and releases any system resources associated with this stream.
void  flush()
Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulated Cipher object to be written out.
void  write(int b)
Writes the specified byte to this output stream.
void  write(byte[] b)
Writes b.length bytes from the specified byte array to this output stream.
void  write(byte[] b, int off, int len)
Writes len bytes from the specified byte array starting at offset off to this output stream.
 
Methods inherited from class java.io.FilterOutputStream
 close, flush, write, write, write
 
Methods inherited from class java.io.OutputStream
 close, flush, write, write, write
 
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,
                          Cipher c)
Constructs a CipherOutputStream from an OutputStream and a Cipher.

CipherOutputStream

protected CipherOutputStream(java.io.OutputStream os)
Constructs a CipherOutputStream from an OutputStream without specifying a Cipher. This has the effect of constructing a CipherOutputStream using a NullCipher.
Method Detail

write

public void write(int b) throws java.io.IOException
Writes the specified byte to this output stream.
Parameters:
b - the byte.
Throws:
java.io.IOException - if an I/O error occurs.
Overrides:
write in class java.io.FilterOutputStream

write

public void write(byte[] b) throws java.io.IOException
Writes b.length bytes from the specified byte array to this output stream.

The write method of CipherOutputStream calls the write method of three arguments with the three arguments b, 0, and b.length.

Parameters:
b - the data.
Throws:
java.io.IOException - if an I/O error occurs.
Overrides:
write in class java.io.FilterOutputStream
See Also:
write(byte[], int, int)

write

public void write(byte[] b,
                  int off,
                  int len) throws java.io.IOException
Writes len bytes from the specified byte array starting at offset off to this output stream.
Parameters:
b - the data.
off - the start offset in the data.
len - the number of bytes to write.
Throws:
java.io.IOException - if an I/O error occurs.
Overrides:
write in class java.io.FilterOutputStream

flush

public void flush() throws java.io.IOException
Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulated Cipher object to be written out.
Throws:
java.io.IOException - if an I/O error occurs.
Overrides:
flush in class java.io.FilterOutputStream

close

public void close() throws java.io.IOException
Closes this output stream and releases any system resources associated with this stream.

Any bytes buffered by the encapsulated Cipher object are processed, and the result is written out by calling the flush method of CipherOutputStream.

This method resets the encapsulated Cipher object to its initial state and calls the close method of the underlying output stream.

Throws:
java.io.IOException - if an I/O error occurs.
Overrides:
close in class java.io.FilterOutputStream

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