- 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:
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Field Summary
Fields declared in class java.io.FilterInputStream
in -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedConstructs aCipherInputStreamfrom anInputStreamwithout specifying aCipherobject.CipherInputStream(InputStream is, Cipher c) Constructs aCipherInputStreamfrom anInputStreamand aCipherobject. -
Method Summary
Modifier and TypeMethodDescriptionintReturns the number of bytes that can be read from this input stream without blocking.voidclose()Closes this input stream and releases any system resources associated with the stream.booleanTests if this input stream supports themarkandresetmethods, which it does not.intread()Reads the next byte of data from this input stream.intread(byte[] b) Reads up tob.lengthbytes of data from this input stream into an array of bytes.intread(byte[] b, int off, int len) Reads up tolenbytes of data from this input stream into an array of bytes.longskip(long n) Skipsnbytes of input from the bytes that can be read from this input stream without blocking.Methods declared in class java.io.FilterInputStream
mark, resetMethods declared in class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo
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Constructor Details
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CipherInputStream
Constructs aCipherInputStreamfrom anInputStreamand aCipherobject.
Note: if the specified input stream or cipher isnull, aNullPointerExceptionmay be thrown later when they are used.- Parameters:
is- the to-be-processed input streamc- an initializedCipherobject
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CipherInputStream
Constructs aCipherInputStreamfrom anInputStreamwithout specifying aCipherobject. This has the effect of constructing aCipherInputStreamusing aNullCipher.
Note: if the specified input stream isnull, aNullPointerExceptionmay be thrown later when it is used.- Parameters:
is- the to-be-processed input stream
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Method Details
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read
Reads the next byte of data from this input stream. The value byte is returned as anintin the range0to255. If no byte is available because the end of the stream has been reached, the value-1is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.- Overrides:
readin classFilterInputStream- Returns:
- the next byte of data, or
-1if the end of the stream is reached. - Throws:
IOException- if an I/O error occurs.- See Also:
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read
Reads up tob.lengthbytes of data from this input stream into an array of bytes.The
readmethod ofInputStreamcalls thereadmethod of three arguments with the argumentsb,0, andb.length.- Overrides:
readin classFilterInputStream- Parameters:
b- the buffer into which the data is read.- Returns:
- the total number of bytes read into the buffer, or
-1is there is no more data because the end of the stream has been reached. - Throws:
IOException- if an I/O error occurs.- See Also:
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read
Reads up tolenbytes 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 tolenbytes are read and discarded.- Overrides:
readin classFilterInputStream- Parameters:
b- the buffer into which the data is read.off- the start offset in the destination arraybuflen- the maximum number of bytes read.- Returns:
- the total number of bytes read into the buffer, or
-1if there is no more data because the end of the stream has been reached. - Throws:
IOException- if an I/O error occurs.- See Also:
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skip
Skipsnbytes 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
nor the result of a call toavailable, whichever is smaller. Ifnis less than zero, no bytes are skipped.The actual number of bytes skipped is returned.
- Overrides:
skipin 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:
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available
Returns the number of bytes that can be read from this input stream without blocking. Theavailablemethod ofInputStreamreturns0. This method should be overridden by subclasses.- Overrides:
availablein classFilterInputStream- Returns:
- the number of bytes that can be read from this input stream without blocking.
- Throws:
IOException- if an I/O error occurs.
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close
Closes this input stream and releases any system resources associated with the stream.The
closemethod ofCipherInputStreamcalls theclosemethod of its underlying input stream.- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Overrides:
closein classFilterInputStream- Throws:
IOException- if an I/O error occurs.- See Also:
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markSupported
public boolean markSupported()Tests if this input stream supports themarkandresetmethods, which it does not.- Overrides:
markSupportedin classFilterInputStream- Returns:
false, since this class does not support themarkandresetmethods.- See Also:
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