org.zkoss.poi.poifs.crypt

Class Decryptor

java.lang.Object

org.zkoss.poi.poifs.crypt.Decryptor

Direct Known Subclasses:

AgileDecryptor, EcmaDecryptor

public abstract class Decryptor
extends Object

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_PASSWORD

Constructor Summary

Constructors

Constructor and Description
Decryptor()

Method Summary

Modifier and Type	Method and Description
protected static int	getBlockSize(int algorithm)
abstract InputStream	getDataStream(DirectoryNode dir) Return a stream with decrypted data.
InputStream	getDataStream(NPOIFSFileSystem fs)
InputStream	getDataStream(POIFSFileSystem fs)
static Decryptor	getInstance(EncryptionInfo info)
abstract long	getLength() Returns the length of the encytpted data that can be safely read with getDataStream(org.zkoss.poi.poifs.filesystem.DirectoryNode).
protected byte[]	hashPassword(EncryptionInfo info, String password)
abstract boolean	verifyPassword(String password)

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PASSWORD

public static final String DEFAULT_PASSWORD

See Also:

Constant Field Values

Constructor Detail

Decryptor

public Decryptor()

Method Detail

getDataStream

public abstract InputStream getDataStream(DirectoryNode dir)
                                   throws IOException,
                                          GeneralSecurityException

Return a stream with decrypted data.

Use 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

Parameters:

dir - the node to read from

Returns:

decrypted stream

Throws:

IOException

GeneralSecurityException

verifyPassword

public abstract boolean verifyPassword(String password)
                                throws GeneralSecurityException

Throws:

GeneralSecurityException

getLength

public abstract long getLength()

Returns the length of the encytpted data that can be safely read with getDataStream(org.zkoss.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 getDataStream(org.zkoss.poi.poifs.filesystem.DirectoryNode), an attempt to call getLength() prior to getDataStream() will result in IllegalStateException.

Returns:

length of the encrypted data

Throws:

IllegalStateException - if getDataStream(org.zkoss.poi.poifs.filesystem.DirectoryNode) was not called

getInstance

public static Decryptor getInstance(EncryptionInfo info)

getDataStream

public InputStream getDataStream(NPOIFSFileSystem fs)
                          throws IOException,
                                 GeneralSecurityException

Throws:

IOException

GeneralSecurityException

getDataStream

public InputStream getDataStream(POIFSFileSystem fs)
                          throws IOException,
                                 GeneralSecurityException

Throws:

IOException

GeneralSecurityException

getBlockSize

protected static int getBlockSize(int algorithm)

hashPassword

protected byte[] hashPassword(EncryptionInfo info,
                              String password)
                       throws NoSuchAlgorithmException

Throws:

NoSuchAlgorithmException