- 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:
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Field Summary
Fields declared in class java.io.FilterOutputStream
out -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedConstructs aCipherOutputStreamfrom anOutputStreamwithout specifying aCipherobject.CipherOutputStream(OutputStream os, Cipher c) Constructs aCipherOutputStreamfrom anOutputStreamand aCipherobject. -
Method Summary
Modifier and TypeMethodDescriptionvoidclose()Closes this output stream and releases any system resources associated with this stream.voidflush()Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulatedCipherobject to be written out.voidwrite(byte[] b) Writesb.lengthbytes from the specified byte array to this output stream.voidwrite(byte[] b, int off, int len) Writeslenbytes from the specified byte array starting at offsetoffto this output stream.voidwrite(int b) Writes the specified byte to this output stream.Methods declared in class java.io.OutputStream
nullOutputStream
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Constructor Details
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CipherOutputStream
Constructs aCipherOutputStreamfrom anOutputStreamand aCipherobject.
Note: if the specified output stream or cipher isnull,a NullPointerExceptionmay be thrown later when they are used.- Parameters:
os- theOutputStreamobjectc- an initializedCipherobject
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CipherOutputStream
Constructs aCipherOutputStreamfrom anOutputStreamwithout specifying aCipherobject. This has the effect of constructing aCipherOutputStreamusing aNullCipher.
Note: if the specified output stream isnull, aNullPointerExceptionmay be thrown later when it is used.- Parameters:
os- theOutputStreamobject
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Method Details
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write
Writes the specified byte to this output stream.- Overrides:
writein classFilterOutputStream- Parameters:
b- thebyte.- Throws:
IOException- if an I/O error occurs.
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write
Writesb.lengthbytes from the specified byte array to this output stream.The
writemethod ofCipherOutputStreamcalls thewritemethod of three arguments with the three argumentsb,0, andb.length.- Overrides:
writein classFilterOutputStream- Parameters:
b- the data.- Throws:
NullPointerException- ifbisnull.IOException- if an I/O error occurs.- See Also:
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write
Writeslenbytes from the specified byte array starting at offsetoffto this output stream.- Overrides:
writein 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:
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flush
Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulatedCipherobject to be written out.Any bytes buffered by the encapsulated
Cipherobject and waiting to be processed by it will not be written out. For example, if the encapsulatedCipherobject is a block cipher, and the total number of bytes written using one of thewritemethods is less than the cipher's block size, no bytes will be written out.- Specified by:
flushin interfaceFlushable- Overrides:
flushin classFilterOutputStream- Throws:
IOException- if an I/O error occurs.- See Also:
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close
Closes this output stream and releases any system resources associated with this stream.This method invokes the
doFinalmethod of the encapsulatedCipherobject, which causes any bytes buffered by the encapsulatedCipherobject to be processed. The result is written out by calling theflushmethod of this output stream.This method resets the encapsulated
Cipherobject to its initial state and calls theclosemethod of the underlying output stream.- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Overrides:
closein classFilterOutputStream- Throws:
IOException- if an I/O error occurs.- See Also:
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