Class CipherOutputStream

public class CipherOutputStream
extends 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. In particular, this class catches BadPaddingException and other exceptions thrown by failed integrity checks during decryption. These exceptions are not re-thrown, so the client will not be informed that integrity checks failed. Because of this behavior, this class may not be suitable for use with decryption in an authenticated mode of operation (e.g. GCM) if the application requires explicit notification when authentication fails. Such an application can use the Cipher API directly as an alternative to using this class.

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.

Constructors

CipherOutputStream

public CipherOutputStream(OutputStream os,
                          Cipher c)

Constructs a CipherOutputStream from an OutputStream and a Cipher.
Note: if the specified output stream or cipher is null, a NullPointerException may be thrown later when they are used.

Parameters:

os - the OutputStream object

c - an initialized Cipher object

CipherOutputStream

protected CipherOutputStream(OutputStream os)

Constructs a CipherOutputStream from an OutputStream without specifying a Cipher. This has the effect of constructing a CipherOutputStream using a NullCipher.
Note: if the specified output stream is null, a NullPointerException may be thrown later when it is used.

Parameters:

os - the OutputStream object

Methods

write

public void write(int b)
           throws IOException

Writes the specified byte to this output stream.

Overrides:

write in class FilterOutputStream

Parameters:

b - the byte.

Throws:

IOException - if an I/O error occurs.

Since:

JCE1.2

write

public void write(byte[] b)
           throws IOException

Overrides:

write in class FilterOutputStream

Parameters:

b - the data.

Throws:

NullPointerException - if b is null.

IOException - if an I/O error occurs.

Since:

JCE1.2

See Also:

write(byte[], int, int)

write

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

Writes len bytes from the specified byte array starting at offset off to this output stream.

Overrides:

write in class FilterOutputStream

Parameters:

b - the data.

off - the start offset in the data.

len - the number of bytes to write.

Throws:

IOException - if an I/O error occurs.

Since:

JCE1.2

See Also:

FilterOutputStream.write(int)

flush

public void flush()
           throws IOException

Specified by:

flush in interface Flushable

Overrides:

flush in class FilterOutputStream

Throws:

IOException - if an I/O error occurs.

Since:

JCE1.2

See Also:

FilterOutputStream.out

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class FilterOutputStream

Throws:

IOException - if an I/O error occurs.

Since:

JCE1.2

See Also:

FilterOutputStream.flush(), FilterOutputStream.out