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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--java.io.InputStream | +--java.io.FilterInputStream | +--javax.crypto.CipherInputStream
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.
InputStream
,
FilterInputStream
,
Cipher
,
CipherOutputStream
Field Summary | |
static java.lang.String |
ident
|
Fields inherited from class java.io.FilterInputStream |
in |
Constructor Summary | |
protected |
CipherInputStream(java.io.InputStream in)
Constructs a CipherInputStream from an InputStream without specifying a Cipher. |
|
CipherInputStream(java.io.InputStream in,
Cipher cipher)
Constructs a CipherInputStream from an InputStream and a Cipher. |
Method Summary | |
int |
available()
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 |
markSupported()
Tests if this input stream supports the mark and reset methods, which it does not. |
int |
read()
Reads the next byte of data from this input stream. |
int |
read(byte[] b)
Reads up to b.length bytes of data from this input stream into an array of bytes. |
int |
read(byte[] b,
int off,
int len)
Reads up to len bytes of data from this input stream into an array of bytes. |
long |
skip(long n)
Skips n bytes of input that can be read from this input stream without blocking. |
Methods inherited from class java.io.FilterInputStream |
mark,
reset |
Methods inherited from class java.lang.Object |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait |
Field Detail |
public static final java.lang.String ident
Constructor Detail |
public CipherInputStream(java.io.InputStream in, Cipher cipher)
in
- The input stream.cipher
- The decrypting/encrypting object.protected CipherInputStream(java.io.InputStream in)
in
- The input stream.Method Detail |
public int read() throws java.io.IOException
read(byte[], int, int)
public int read(byte[] b) throws java.io.IOException
The read method of InputStream calls the read method of three arguments with the arguments b, 0, and b.length.
b
- the buffer into which the data is read.read(byte[], int, int)
public int read(byte[] b, int off, int len) throws java.io.IOException
b
- the buffer into which the data is read.off
- the start offset of the data.len
- the maximum number of bytes read.read()
public long skip(long n) throws java.io.IOException
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.
n
- the number of bytes to be skipped.public int available() throws java.io.IOException
public void close() throws java.io.IOException
The close method of CipherInputStream calls the close method of its underlying input stream.
public boolean markSupported()
FilterInputStream.mark(int)
,
FilterInputStream.reset()
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