Closeable
, Flushable
, AutoCloseable
public class CipherOutputStream extends FilterOutputStream
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
.
out
Modifier | Constructor | Description |
---|---|---|
protected |
Constructs a CipherOutputStream from an OutputStream without specifying a Cipher object. |
|
Constructs a CipherOutputStream from an OutputStream and a Cipher object. |
Modifier and Type | Method | Description |
---|---|---|
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 |
Writes b.length bytes from the specified byte array to this output stream. |
void |
write |
Writes len bytes from the specified byte array starting at offset off to this output stream. |
void |
write |
Writes the specified byte to this output stream. |
nullOutputStream
public CipherOutputStream(OutputStream os, Cipher c)
CipherOutputStream
from an OutputStream
and a Cipher
object. null
, a NullPointerException
may be thrown later when they are used.os
- the OutputStream
objectc
- an initialized Cipher
objectprotected CipherOutputStream(OutputStream os)
CipherOutputStream
from an OutputStream
without specifying a Cipher
object. This has the effect of constructing a CipherOutputStream
using a NullCipher
. null
, a NullPointerException
may be thrown later when it is used.os
- the OutputStream
objectpublic void write(int b) throws IOException
write
in class FilterOutputStream
b
- the byte
.IOException
- if an I/O error occurs.public void write(byte[] b) throws IOException
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
.
write
in class FilterOutputStream
b
- the data.NullPointerException
- if b
is null
.IOException
- if an I/O error occurs.public void write(byte[] b, int off, int len) throws IOException
len
bytes from the specified byte array starting at offset off
to this output stream.write
in class FilterOutputStream
b
- the data.off
- the start offset in the data.len
- the number of bytes to write.IOException
- if an I/O error occurs.public void flush() throws IOException
Cipher
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 encapsulated Cipher
object is a block cipher, and the total number of bytes written using one of the write
methods is less than the cipher's block size, no bytes will be written out.
flush
in interface Flushable
flush
in class FilterOutputStream
IOException
- if an I/O error occurs.public void close() throws IOException
This method invokes the doFinal
method of the encapsulated Cipher
object, which causes any bytes buffered by the encapsulated Cipher
object to be processed. The result is written out by calling the flush
method of this output stream.
This method resets the encapsulated Cipher
object to its initial state and calls the close
method of the underlying output stream.
close
in interface AutoCloseable
close
in interface Closeable
close
in class FilterOutputStream
IOException
- if an I/O error occurs.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/javax/crypto/CipherOutputStream.html