CipherOutputStream (Java SE 11 & JDK 11 ) (original) (raw)

• java.lang.Object

• • java.io.OutputStream
  • • java.io.FilterOutputStream
      • • javax.crypto.CipherOutputStream

• All Implemented Interfaces:
  [Closeable](../../java/io/Closeable.html "interface in java.io"), [Flushable](../../java/io/Flushable.html "interface in java.io"), [AutoCloseable](../../java/lang/AutoCloseable.html "interface in java.lang")

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.
Since:
1.4
See Also:
OutputStream, FilterOutputStream, Cipher, CipherInputStream

• • Field Summary

     * ### Fields declared in class java.io.[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")  
     `[out](../../java/io/FilterOutputStream.html#out)`  

  • Constructor Summary

  Constructors

  Modifier	Constructor	Description
  protected	CipherOutputStream​(OutputStream os)	Constructs a CipherOutputStream from an OutputStream without specifying a Cipher.
  	CipherOutputStream​(OutputStream os,Cipher c)	Constructs a CipherOutputStream from an OutputStream and a Cipher.

  • Method Summary

  All Methods Instance Methods Concrete Methods

  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​(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.
  void	write​(int b)	Writes the specified byte to this output stream.

     * ### Methods declared in class java.io.[OutputStream](../../java/io/OutputStream.html "class in java.io")  
     `[nullOutputStream](../../java/io/OutputStream.html#nullOutputStream%28%29)`  
     * ### Methods declared in class java.lang.[Object](../../java/lang/Object.html "class in java.lang")  
     `[clone](../../java/lang/Object.html#clone%28%29), [equals](../../java/lang/Object.html#equals%28java.lang.Object%29), [finalize](../../java/lang/Object.html#finalize%28%29), [getClass](../../java/lang/Object.html#getClass%28%29), [hashCode](../../java/lang/Object.html#hashCode%28%29), [notify](../../java/lang/Object.html#notify%28%29), [notifyAll](../../java/lang/Object.html#notifyAll%28%29), [toString](../../java/lang/Object.html#toString%28%29), [wait](../../java/lang/Object.html#wait%28%29), [wait](../../java/lang/Object.html#wait%28long%29), [wait](../../java/lang/Object.html#wait%28long,int%29)`

• • Constructor Detail

     * #### CipherOutputStream  
     public CipherOutputStream​([OutputStream](../../java/io/OutputStream.html "class in java.io") os,  
                               [Cipher](Cipher.html "class in javax.crypto") 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](../../java/io/OutputStream.html "class in java.io") 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  

  • Method Detail

    * #### write  
    public void write​(int b)  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    Writes the specified byte to this output stream.  
    Overrides:  
    `[write](../../java/io/FilterOutputStream.html#write%28int%29)` in class `[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")`  
    Parameters:  
    `b` \- the `byte`.  
    Throws:  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    * #### write  
    public void write​(byte[] b)  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    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`.  
    Overrides:  
    `[write](../../java/io/FilterOutputStream.html#write%28byte%5B%5D%29)` in class `[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")`  
    Parameters:  
    `b` \- the data.  
    Throws:  
    `[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang")` \- if `b` is null.  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    See Also:  
    [write(byte\[\], int, int)](#write%28byte%5B%5D,int,int%29)  
    * #### write  
    public void write​(byte[] b,  
                      int off,  
                      int len)  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    Writes `len` bytes from the specified byte array starting at offset `off` to this output stream.  
    Overrides:  
    `[write](../../java/io/FilterOutputStream.html#write%28byte%5B%5D,int,int%29)` in class `[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")`  
    Parameters:  
    `b` \- the data.  
    `off` \- the start offset in the data.  
    `len` \- the number of bytes to write.  
    Throws:  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    See Also:  
    [FilterOutputStream.write(int)](../../java/io/FilterOutputStream.html#write%28int%29)  
    * #### flush  
    public void flush()  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulated cipher object to be written out.  
    Any bytes buffered by the encapsulated cipher and waiting to be processed by it will not be written out. For example, if the encapsulated cipher 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.  
    Specified by:  
    `[flush](../../java/io/Flushable.html#flush%28%29)` in interface `[Flushable](../../java/io/Flushable.html "interface in java.io")`  
    Overrides:  
    `[flush](../../java/io/FilterOutputStream.html#flush%28%29)` in class `[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")`  
    Throws:  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    See Also:  
    [FilterOutputStream.out](../../java/io/FilterOutputStream.html#out)  
    * #### close  
    public void close()  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    Closes this output stream and releases any system resources associated with this stream.  
     This method invokes the `doFinal` method of the encapsulated cipher object, which causes any bytes buffered by the encapsulated cipher 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.  
    Specified by:  
    `[close](../../java/lang/AutoCloseable.html#close%28%29)` in interface `[AutoCloseable](../../java/lang/AutoCloseable.html "interface in java.lang")`  
    Specified by:  
    `[close](../../java/io/Closeable.html#close%28%29)` in interface `[Closeable](../../java/io/Closeable.html "interface in java.io")`  
    Overrides:  
    `[close](../../java/io/FilterOutputStream.html#close%28%29)` in class `[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")`  
    Throws:  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    See Also:  
    [FilterOutputStream.flush()](../../java/io/FilterOutputStream.html#flush%28%29), [FilterOutputStream.out](../../java/io/FilterOutputStream.html#out)

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