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Class javax.crypto.CipherInputStream
java.lang.Object
|
+----java.io.InputStream
|
+----java.io.FilterInputStream
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+----javax.crypto.CipherInputStream
- public class CipherInputStream
- extends FilterInputStream
A CipherInputStream is composed of an InputStream and a Cipher so that
read() methods return data that are read in from the underlying InputStream but
have been additionally processed by the Cipher. The Cipher must be fully
initialised before being used by a CipherInputStream.
For example, if the Cipher is initialised for decryption, the CipherInputStream
will attempt to read in data and decrypt them, before returning the decrypted
data.
This class adheres strictly to the semantics, especially the failure semantics,
of its ancestor classes java.io.FilterInputStream and java.io.InputStream. 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, the skip() method skips
only data that have been processed by the encapsulated Cipher.
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
CipherInputStream.
- See Also:
- InputStream, FilterInputStream, Cipher, CipherOutputStream
-
ident
-
-
CipherInputStream(InputStream)
- Constructs a CipherInputStream from an InputStream without specifying
a Cipher.
-
CipherInputStream(InputStream, Cipher)
- Constructs a CipherInputStream from an InputStream and a Cipher.
-
available()
- Returns the number of bytes that can be read from this input stream
without blocking.
-
close()
- Closes this input stream and releases any system resources associated
with the stream.
-
markSupported()
- Tests if this input stream supports the mark and reset methods,
which it does not.
-
read()
- Reads the next byte of data from this input stream.
-
read(byte[])
- Reads up to b.length bytes of data from this input stream into an array
of bytes.
-
read(byte[], int, int)
- Reads up to len bytes of data from this input stream into an array
of bytes.
-
skip(long)
- Skips n bytes of input that can be read from this input stream
without blocking.
ident
public static final String ident
CipherInputStream
public CipherInputStream(InputStream in,
Cipher cipher)
- Constructs a CipherInputStream from an InputStream and a Cipher.
- Parameters:
- in - The input stream.
- cipher - The decrypting/encrypting object.
CipherInputStream
protected CipherInputStream(InputStream in)
- Constructs a CipherInputStream from an InputStream without specifying
a Cipher. This has the effect of constructing a CipherInputStream
using a NullCipher.
- Parameters:
- in - The input stream.
read
public int read() throws IOException
- Reads the next byte of data from this input stream. The value byte
is returned as an int in the range 0 to 255. If no byte is available
because the end of the stream has been reached, the value -1 is
returned. This method blocks until input data is available, the end
of the stream is detected, or an exception is thrown.
- Returns:
- the next byte of data, or -1 if the end of the stream
is reached.
- Throws: IOException
- if an I/O error occurs.
- Overrides:
- read in class FilterInputStream
- See Also:
- read
read
public int read(byte b[]) throws IOException
- Reads up to b.length bytes of data from this input stream into an array
of bytes.
The read method of InputStream calls the read method of three
arguments with the arguments b, 0, and b.length.
- Parameters:
- b - the buffer into which the data is read.
- Returns:
- the total number of bytes read into the buffer, or -1 if
there is no more data because the end of the stream has been
reached.
- Throws: IOException
- if an I/O error occurs.
- Overrides:
- read in class FilterInputStream
- See Also:
- read
read
public int read(byte b[],
int off,
int len) throws IOException
- Reads up to len bytes of data from this input stream into an array
of bytes. This method blocks until some input is available. If the
first argument is null, up to len bytes are read and discarded.
- Parameters:
- b - the buffer into which the data is read.
- off - the start offset of the data.
- len - the maximum number of bytes read.
- Returns:
- the total number of bytes read into the buffer, or -1 if
there is no more data because the end of the stream has been
reached.
- Throws: IOException
- if an I/O error occurs.
- Overrides:
- read in class FilterInputStream
- See Also:
- read
skip
public long skip(long n) throws IOException
- Skips n bytes of input that can be read from this input stream
without blocking.
Fewer bytes than requested might be skipped. The actual number of
bytes skipped is equal to n or the result of a call to available,
whichever is smaller. If n is less than zero, no bytes are
skipped.
The actual number of bytes skipped is returned.
- Parameters:
- n - the number of bytes to be skipped.
- Returns:
- the actual number of bytes skipped.
- Throws: IOException
- if an I/O error occurs.
- Overrides:
- skip in class FilterInputStream
available
public int available() throws IOException
- Returns the number of bytes that can be read from this input stream
without blocking. The available method of InputStream returns 0.
This method should be overridden by subclasses.
- Returns:
- the number of bytes that can be read from this input stream
without blocking.
- Throws: IOException
- if an I/O error occurs.
- Overrides:
- available in class FilterInputStream
close
public void close() throws IOException
- Closes this input stream and releases any system resources associated
with the stream.
The close method of CipherInputStream calls the close method of its
underlying input stream.
- Throws: IOException
- - if an I/O error occurs.
- Overrides:
- close in class FilterInputStream
markSupported
public boolean markSupported()
- Tests if this input stream supports the mark and reset methods,
which it does not.
- Returns:
- false, since this class does not support the mark and
reset methods.
- Overrides:
- markSupported in class FilterInputStream
- See Also:
- mark, reset
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