org.apache.poi.poifs.crypt

Class ChunkedCipherInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

org.apache.poi.util.LittleEndianInputStream

org.apache.poi.poifs.crypt.ChunkedCipherInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, LittleEndianInput

@Internal
public abstract class ChunkedCipherInputStream
extends LittleEndianInputStream

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor and Description
ChunkedCipherInputStream(java.io.InputStream stream, long size, int chunkSize)
ChunkedCipherInputStream(java.io.InputStream stream, long size, int chunkSize, int initialPos)

Method Summary

Modifier and Type	Method and Description
int	available()
protected byte[]	getChunk()
protected int	getChunkMask()
protected byte[]	getPlain()
long	getPos()
protected abstract javax.crypto.Cipher	initCipherForBlock(javax.crypto.Cipher existing, int block)
javax.crypto.Cipher	initCipherForBlock(int block)
protected int	invokeCipher(int totalBytes, boolean doFinal) Helper function for overriding the cipher invocation, i.e. (用于覆盖密码调用的辅助函数，即)
void	mark(int readlimit)
boolean	markSupported()
int	read()
int	read(byte[] b, int off, int len)
void	readPlain(byte[] b, int off, int len) Used when BIFF header fields (sid, size) are being read. (在读取 BIFF 标头字段（sid、size）时使用。)
void	reset()
void	setNextRecordSize(int recordSize) Some ciphers (actually just XOR) are based on the record size, which needs to be set before decryption (一些密码（实际上只是异或）是基于记录大小的，需要在解密前设置)
long	skip(long n)

Methods inherited from class org.apache.poi.util.LittleEndianInputStream

getReadIndex, readByte, readDouble, readFloat, readFully, readFully, readInt, readLong, readShort, readUByte, readUInt, readUShort, skipFully

Methods inherited from class java.io.FilterInputStream

close, read

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ChunkedCipherInputStream

public ChunkedCipherInputStream(java.io.InputStream stream,
                                long size,
                                int chunkSize)
                         throws java.security.GeneralSecurityException

Throws:

java.security.GeneralSecurityException (java.security.GeneralSecurityException)

ChunkedCipherInputStream

public ChunkedCipherInputStream(java.io.InputStream stream,
                                long size,
                                int chunkSize,
                                int initialPos)
                         throws java.security.GeneralSecurityException

Throws:

java.security.GeneralSecurityException (java.security.GeneralSecurityException)

Method Detail

initCipherForBlock

public final javax.crypto.Cipher initCipherForBlock(int block)
                                             throws java.io.IOException,
                                                    java.security.GeneralSecurityException

Throws:

java.io.IOException (java.io.IOException)

java.security.GeneralSecurityException (java.security.GeneralSecurityException)

initCipherForBlock

protected abstract javax.crypto.Cipher initCipherForBlock(javax.crypto.Cipher existing,
                                                          int block)
                                                   throws java.security.GeneralSecurityException

Throws:

java.security.GeneralSecurityException (java.security.GeneralSecurityException)

read

public int read()
         throws java.io.IOException

Overrides:

read in class java.io.FilterInputStream

Throws:

java.io.IOException (java.io.IOException)

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Overrides:

read in class LittleEndianInputStream

Throws:

java.io.IOException (java.io.IOException)

skip

public long skip(long n)

Overrides:

skip in class java.io.FilterInputStream

available

public int available()

Specified by:

available in interface LittleEndianInput (在接口 LittleEndianInput 中可用)

Overrides:

available in class LittleEndianInputStream

markSupported

public boolean markSupported()

Overrides:

markSupported in class java.io.FilterInputStream

mark

public void mark(int readlimit)

Overrides:

mark in class LittleEndianInputStream

reset

public void reset()

Overrides:

reset in class LittleEndianInputStream

getChunkMask

protected int getChunkMask()

invokeCipher

protected int invokeCipher(int totalBytes,
                           boolean doFinal)
                    throws java.security.GeneralSecurityException

Helper function for overriding the cipher invocation, i.e. XOR doesn't use a cipher and uses it's own implementation (用于覆盖密码调用的辅助函数，即 XOR 不使用密码并使用它自己的实现)

Throws:

java.security.GeneralSecurityException (java.security.GeneralSecurityException)

readPlain

public void readPlain(byte[] b,
                      int off,
                      int len)

Used when BIFF header fields (sid, size) are being read. The internal Cipher instance must step even when unencrypted bytes are read (在读取 BIFF 标头字段（sid、size）时使用。即使读取未加密的字节，内部 Cipher 实例也必须执行)

Specified by:

readPlain in interface LittleEndianInput (接口 LittleEndianInput 中的 readPlain)

Overrides:

readPlain in class LittleEndianInputStream

Parameters:

b - the byte array to receive the bytes (b - 接收字节的字节数组)

off - the start offset into the byte array (off - 字节数组的起始偏移量)

len - the amount of bytes to fill (len - 要填充的字节数)

setNextRecordSize

public void setNextRecordSize(int recordSize)

Some ciphers (actually just XOR) are based on the record size, which needs to be set before decryption (一些密码（实际上只是异或）是基于记录大小的，需要在解密前设置)

Parameters:

recordSize - the size of the next record (recordSize - 下一条记录的大小)

getChunk

protected byte[] getChunk()

Returns:

the chunk bytes (块字节)

getPlain

protected byte[] getPlain()

Returns:

the plain bytes (纯字节)

getPos

public long getPos()

Returns:

the absolute position in the stream (流中的绝对位置)