org.apache.poi.poifs.crypt.xor
Class XORDecryptor

java.lang.Object
  extended by org.apache.poi.poifs.crypt.Decryptor
      extended by org.apache.poi.poifs.crypt.xor.XORDecryptor
All Implemented Interfaces:
java.lang.Cloneable

public class XORDecryptor
extends Decryptor
implements java.lang.Cloneable


Field Summary
 
Fields inherited from class org.apache.poi.poifs.crypt.Decryptor
DEFAULT_PASSWORD, DEFAULT_POIFS_ENTRY, encryptionInfo
 
Constructor Summary
protected XORDecryptor()
           
 
Method Summary
 XORDecryptor clone()
           
 ChunkedCipherInputStream getDataStream(DirectoryNode dir)
          Return a stream with decrypted data.
 java.io.InputStream getDataStream(java.io.InputStream stream, int size, int initialPos)
          Wraps a stream for decryption
 long getLength()
          Returns the length of the encrypted data that can be safely read with Decryptor.getDataStream(org.apache.poi.poifs.filesystem.DirectoryNode).
 javax.crypto.Cipher initCipherForBlock(javax.crypto.Cipher cipher, int block)
          Initializes a cipher object for a given block index for encryption
protected static javax.crypto.Cipher initCipherForBlock(javax.crypto.Cipher cipher, int block, EncryptionInfo encryptionInfo, javax.crypto.SecretKey skey, int encryptMode)
           
 void setChunkSize(int chunkSize)
          Sets the chunk size of the data stream.
 boolean verifyPassword(java.lang.String password)
           
 
Methods inherited from class org.apache.poi.poifs.crypt.Decryptor
getBlockSizeInBytes, getDataStream, getDataStream, getDataStream, getEncryptionInfo, getInstance, getIntegrityHmacKey, getIntegrityHmacValue, getKeySizeInBytes, getSecretKey, getVerifier, setEncryptionInfo, setIntegrityHmacKey, setIntegrityHmacValue, setSecretKey, setVerifier
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

XORDecryptor

protected XORDecryptor()
Method Detail

verifyPassword

public boolean verifyPassword(java.lang.String password)
Specified by:
verifyPassword in class Decryptor

initCipherForBlock

public javax.crypto.Cipher initCipherForBlock(javax.crypto.Cipher cipher,
                                              int block)
                                       throws java.security.GeneralSecurityException
Description copied from class: Decryptor
Initializes a cipher object for a given block index for encryption

Overrides:
initCipherForBlock in class Decryptor
Parameters:
cipher - may be null, otherwise the given instance is reset to the new block index
block - the block index, e.g. the persist/slide id (hslf)
Returns:
a new cipher object, if cipher was null, otherwise the reinitialized cipher
Throws:
java.security.GeneralSecurityException

initCipherForBlock

protected static javax.crypto.Cipher initCipherForBlock(javax.crypto.Cipher cipher,
                                                        int block,
                                                        EncryptionInfo encryptionInfo,
                                                        javax.crypto.SecretKey skey,
                                                        int encryptMode)
                                                 throws java.security.GeneralSecurityException
Throws:
java.security.GeneralSecurityException

getDataStream

public ChunkedCipherInputStream getDataStream(DirectoryNode dir)
                                       throws java.io.IOException,
                                              java.security.GeneralSecurityException
Description copied from class: Decryptor
Return a stream with decrypted data.

Use Decryptor.getLength() to get the size of that data that can be safely read from the stream. Just reading to the end of the input stream is not sufficient because there are normally padding bytes that must be discarded

Specified by:
getDataStream in class Decryptor
Parameters:
dir - the node to read from
Returns:
decrypted stream
Throws:
java.io.IOException
java.security.GeneralSecurityException

getDataStream

public java.io.InputStream getDataStream(java.io.InputStream stream,
                                         int size,
                                         int initialPos)
                                  throws java.io.IOException,
                                         java.security.GeneralSecurityException
Description copied from class: Decryptor
Wraps a stream for decryption

As we are handling streams and don't know the total length beforehand, it's the callers duty to care for the length of the entries.

Overrides:
getDataStream in class Decryptor
Parameters:
stream - the stream to be wrapped
initialPos - initial/current byte position within the stream
Returns:
decrypted stream
Throws:
java.io.IOException
java.security.GeneralSecurityException

getLength

public long getLength()
Description copied from class: Decryptor
Returns the length of the encrypted data that can be safely read with Decryptor.getDataStream(org.apache.poi.poifs.filesystem.DirectoryNode). Just reading to the end of the input stream is not sufficient because there are normally padding bytes that must be discarded

The length variable is initialized in Decryptor.getDataStream(org.apache.poi.poifs.filesystem.DirectoryNode), an attempt to call getLength() prior to getDataStream() will result in IllegalStateException.

Specified by:
getLength in class Decryptor
Returns:
length of the encrypted data

setChunkSize

public void setChunkSize(int chunkSize)
Description copied from class: Decryptor
Sets the chunk size of the data stream. Needs to be set before the data stream is requested. When not set, the implementation uses method specific default values

Overrides:
setChunkSize in class Decryptor
Parameters:
chunkSize - the chunk size, i.e. the block size with the same encryption key

clone

public XORDecryptor clone()
                   throws java.lang.CloneNotSupportedException
Overrides:
clone in class Decryptor
Throws:
java.lang.CloneNotSupportedException