- All Implemented Interfaces:
Closeable
,Flushable
,AutoCloseable
CipherOutputStream
is composed of an OutputStream
and a Cipher
object so that write() methods first process the data
before writing them out to the underlying OutputStream
.
The Cipher
object must be fully initialized before being used by a
CipherOutputStream
.
For example, if the Cipher
object 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 overridden 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:
- 1.4
- See Also:
-
Field Summary
Fields declared in class java.io.FilterOutputStream
out
-
Constructor Summary
ModifierConstructorDescriptionprotected
Constructs aCipherOutputStream
from anOutputStream
without specifying aCipher
object.CipherOutputStream
(OutputStream os, Cipher c) Constructs aCipherOutputStream
from anOutputStream
and aCipher
object. -
Method Summary
Modifier and TypeMethodDescriptionvoid
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 encapsulatedCipher
object to be written out.void
write
(byte[] b) Writesb.length
bytes from the specified byte array to this output stream.void
write
(byte[] b, int off, int len) Writeslen
bytes from the specified byte array starting at offsetoff
to this output stream.void
write
(int b) Writes the specified byte to this output stream.Methods declared in class java.io.OutputStream
nullOutputStream
-
Constructor Details
-
CipherOutputStream
Constructs aCipherOutputStream
from anOutputStream
and aCipher
object.
Note: if the specified output stream or cipher isnull
,a NullPointerException
may be thrown later when they are used.- Parameters:
os
- theOutputStream
objectc
- an initializedCipher
object
-
CipherOutputStream
Constructs aCipherOutputStream
from anOutputStream
without specifying aCipher
object. This has the effect of constructing aCipherOutputStream
using aNullCipher
.
Note: if the specified output stream isnull
, aNullPointerException
may be thrown later when it is used.- Parameters:
os
- theOutputStream
object
-
-
Method Details
-
write
Writes the specified byte to this output stream.- Overrides:
write
in classFilterOutputStream
- Parameters:
b
- thebyte
.- Throws:
IOException
- if an I/O error occurs.
-
write
Writesb.length
bytes from the specified byte array to this output stream.The
write
method ofCipherOutputStream
calls thewrite
method of three arguments with the three argumentsb
,0
, andb.length
.- Overrides:
write
in classFilterOutputStream
- Parameters:
b
- the data.- Throws:
NullPointerException
- ifb
isnull
.IOException
- if an I/O error occurs.- See Also:
-
write
Writeslen
bytes from the specified byte array starting at offsetoff
to this output stream.- Overrides:
write
in classFilterOutputStream
- 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.- See Also:
-
flush
Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulatedCipher
object to be written out.Any bytes buffered by the encapsulated
Cipher
object and waiting to be processed by it will not be written out. For example, if the encapsulatedCipher
object is a block cipher, and the total number of bytes written using one of thewrite
methods is less than the cipher's block size, no bytes will be written out.- Specified by:
flush
in interfaceFlushable
- Overrides:
flush
in classFilterOutputStream
- Throws:
IOException
- if an I/O error occurs.- See Also:
-
close
Closes this output stream and releases any system resources associated with this stream.This method invokes the
doFinal
method of the encapsulatedCipher
object, which causes any bytes buffered by the encapsulatedCipher
object to be processed. The result is written out by calling theflush
method of this output stream.This method resets the encapsulated
Cipher
object to its initial state and calls theclose
method of the underlying output stream.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classFilterOutputStream
- Throws:
IOException
- if an I/O error occurs.- See Also:
-