- All Implemented Interfaces:
Closeable
,AutoCloseable
CipherInputStream
is composed of an InputStream
and a Cipher
object so that read() methods return data that are
read in from the underlying InputStream
but have been
additionally processed by the Cipher
object. The Cipher
object must be fully initialized before being used by a
CipherInputStream
.
For example, if the Cipher
object is initialized 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, and the available
method counts only data that have been processed by the encapsulated
Cipher
object.
This class may catch BadPaddingException
and other exceptions
thrown by failed integrity checks during decryption. These exceptions are not
re-thrown, so the client may 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).
Applications that require authenticated encryption 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
CipherInputStream
.
- Since:
- 1.4
- See Also:
-
Field Summary
Fields declared in class java.io.FilterInputStream
in
-
Constructor Summary
ModifierConstructorDescriptionprotected
Constructs aCipherInputStream
from anInputStream
without specifying aCipher
object.CipherInputStream
(InputStream is, Cipher c) Constructs aCipherInputStream
from anInputStream
and aCipher
object. -
Method Summary
Modifier and TypeMethodDescriptionint
Returns the number of bytes that can be read from this input stream without blocking.void
close()
Closes this input stream and releases any system resources associated with the stream.boolean
Tests if this input stream supports themark
andreset
methods, which it does not.int
read()
Reads the next byte of data from this input stream.int
read
(byte[] b) Reads up tob.length
bytes of data from this input stream into an array of bytes.int
read
(byte[] b, int off, int len) Reads up tolen
bytes of data from this input stream into an array of bytes.long
skip
(long n) Skipsn
bytes of input from the bytes that can be read from this input stream without blocking.Methods declared in class java.io.FilterInputStream
mark, reset
Methods declared in class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo
-
Constructor Details
-
CipherInputStream
Constructs aCipherInputStream
from anInputStream
and aCipher
object.
Note: if the specified input stream or cipher isnull
, aNullPointerException
may be thrown later when they are used.- Parameters:
is
- the to-be-processed input streamc
- an initializedCipher
object
-
CipherInputStream
Constructs aCipherInputStream
from anInputStream
without specifying aCipher
object. This has the effect of constructing aCipherInputStream
using aNullCipher
.
Note: if the specified input stream isnull
, aNullPointerException
may be thrown later when it is used.- Parameters:
is
- the to-be-processed input stream
-
-
Method Details
-
read
Reads the next byte of data from this input stream. The value byte is returned as anint
in the range0
to255
. 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.- Overrides:
read
in classFilterInputStream
- Returns:
- the next byte of data, or
-1
if the end of the stream is reached. - Throws:
IOException
- if an I/O error occurs.- See Also:
-
read
Reads up tob.length
bytes of data from this input stream into an array of bytes.The
read
method ofInputStream
calls theread
method of three arguments with the argumentsb
,0
, andb.length
.- Overrides:
read
in classFilterInputStream
- Parameters:
b
- the buffer into which the data is read.- Returns:
- the total number of bytes read into the buffer, or
-1
is there is no more data because the end of the stream has been reached. - Throws:
IOException
- if an I/O error occurs.- See Also:
-
read
Reads up tolen
bytes of data from this input stream into an array of bytes. This method blocks until some input is available. If the first argument isnull
, up tolen
bytes are read and discarded.- Overrides:
read
in classFilterInputStream
- Parameters:
b
- the buffer into which the data is read.off
- the start offset in the destination arraybuf
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.- See Also:
-
skip
Skipsn
bytes of input from the bytes 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 toavailable
, whichever is smaller. Ifn
is less than zero, no bytes are skipped.The actual number of bytes skipped is returned.
- Overrides:
skip
in classFilterInputStream
- Parameters:
n
- the number of bytes to be skipped.- Returns:
- the actual number of bytes skipped.
- Throws:
IOException
- if an I/O error occurs.- See Also:
-
available
Returns the number of bytes that can be read from this input stream without blocking. Theavailable
method ofInputStream
returns0
. This method should be overridden by subclasses.- Overrides:
available
in classFilterInputStream
- Returns:
- the number of bytes that can be read from this input stream without blocking.
- Throws:
IOException
- if an I/O error occurs.
-
close
Closes this input stream and releases any system resources associated with the stream.The
close
method ofCipherInputStream
calls theclose
method of its underlying input stream.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classFilterInputStream
- Throws:
IOException
- if an I/O error occurs.- See Also:
-
markSupported
public boolean markSupported()Tests if this input stream supports themark
andreset
methods, which it does not.- Overrides:
markSupported
in classFilterInputStream
- Returns:
false
, since this class does not support themark
andreset
methods.- See Also:
-