- java.lang.Object
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- java.io.InputStream
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- java.io.FilterInputStream
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- javax.crypto.CipherInputStream
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- All Implemented Interfaces:
Closeable,AutoCloseable
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 initialized before being used by a CipherInputStream.For example, if the Cipher 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
skipmethod skips, and theavailablemethod counts only data that have been processed by the encapsulated Cipher. 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 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 CipherInputStream.
- Since:
- 1.4
- See Also:
InputStream,FilterInputStream,Cipher,CipherOutputStream
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Field Summary
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Fields declared in class java.io.FilterInputStream
in
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Constructor Summary
Constructors Modifier Constructor Description protectedCipherInputStream(InputStream is)Constructs a CipherInputStream from an InputStream without specifying a Cipher.CipherInputStream(InputStream is, Cipher c)Constructs a CipherInputStream from an InputStream and a Cipher.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description intavailable()Returns 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.booleanmarkSupported()Tests 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, reset
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Methods declared in class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo
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Constructor Detail
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CipherInputStream
public CipherInputStream(InputStream is, Cipher c)
Constructs a CipherInputStream from an InputStream and a Cipher.
Note: if the specified input stream or cipher is null, a NullPointerException may be thrown later when they are used.- Parameters:
is- the to-be-processed input streamc- an initialized Cipher object
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CipherInputStream
protected CipherInputStream(InputStream is)
Constructs a CipherInputStream from an InputStream without specifying a Cipher. This has the effect of constructing a CipherInputStream using a NullCipher.
Note: if the specified input stream is null, a NullPointerException may be thrown later when it is used.- Parameters:
is- the to-be-processed input stream
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Method Detail
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read
public int read() throws IOExceptionReads 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:
FilterInputStream.in
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read
public int read(byte[] b) throws IOExceptionReads 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:
InputStream.read(byte[], int, int)
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read
public int read(byte[] b, int off, int len) throws IOExceptionReads 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:
InputStream.read()
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skip
public long skip(long n) throws IOExceptionSkipsnbytes 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.
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available
public int available() throws IOExceptionReturns 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
public void close() throws IOExceptionCloses 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:
FilterInputStream.in
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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:
InputStream.mark(int),InputStream.reset()
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