Package org.apache.poi.poifs.crypt

Class Decryptor

java.lang.Object

org.apache.poi.poifs.crypt.Decryptor

All Implemented Interfaces:

Cloneable

Direct Known Subclasses:

AgileDecryptor, BinaryRC4Decryptor, CryptoAPIDecryptor, StandardDecryptor, XORDecryptor

public abstract class Decryptor
extends Object
implements Cloneable

Field Summary

Fields

Modifier and Type	Field	Description
static String	DEFAULT_PASSWORD
static String	DEFAULT_POIFS_ENTRY

Method Summary

Modifier and Type	Method	Description
Decryptor	clone()
InputStream	getDataStream(InputStream stream, int size, int initialPos)	Wraps a stream for decryption
abstract InputStream	getDataStream(DirectoryNode dir)	Return a stream with decrypted data.
InputStream	getDataStream(POIFSFileSystem fs)
EncryptionInfo	getEncryptionInfo()
static Decryptor	getInstance(EncryptionInfo info)
byte[]	getIntegrityHmacKey()
byte[]	getIntegrityHmacValue()
abstract long	getLength()	Returns the length of the encrypted data that can be safely read with getDataStream(org.apache.poi.poifs.filesystem.DirectoryNode).
SecretKey	getSecretKey()
byte[]	getVerifier()
Cipher	initCipherForBlock(Cipher cipher, int block)	Initializes a cipher object for a given block index for encryption
void	setChunkSize(int chunkSize)	Sets the chunk size of the data stream.
void	setEncryptionInfo(EncryptionInfo encryptionInfo)
abstract boolean	verifyPassword(String password)

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PASSWORD

public static final String DEFAULT_PASSWORD

See Also:

Constant Field Values

DEFAULT_POIFS_ENTRY

public static final String DEFAULT_POIFS_ENTRY

See Also:

Constant Field Values

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

getDataStream

public InputStream getDataStream(InputStream stream,
                                 int size,
                                 int initialPos)
                          throws IOException,
                                 GeneralSecurityException

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.

Parameters:

stream - the stream to be wrapped

initialPos - initial/current byte position within the stream

Returns:

decrypted stream

Throws:

IOException

GeneralSecurityException

setChunkSize

public void setChunkSize(int chunkSize)

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

Parameters:

chunkSize - the chunk size, i.e. the block size with the same encryption key

initCipherForBlock

public Cipher initCipherForBlock(Cipher cipher,
                                 int block)
                          throws GeneralSecurityException

Initializes a cipher object for a given block index for encryption

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:

GeneralSecurityException - if the cipher can't be initialized

verifyPassword

public abstract boolean verifyPassword(String password)
                                throws GeneralSecurityException

Throws:

GeneralSecurityException

getLength

public abstract long getLength()

Returns the length of the encrypted data that can be safely read with 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 getDataStream(org.apache.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.apache.poi.poifs.filesystem.DirectoryNode) was not called

getInstance

public static Decryptor getInstance(EncryptionInfo info)

getDataStream

public InputStream getDataStream(POIFSFileSystem fs)
                          throws IOException,
                                 GeneralSecurityException

Throws:

IOException

GeneralSecurityException

getVerifier

public byte[] getVerifier()

getSecretKey

public SecretKey getSecretKey()

getIntegrityHmacKey

public byte[] getIntegrityHmacKey()

getIntegrityHmacValue

public byte[] getIntegrityHmacValue()

getEncryptionInfo

public EncryptionInfo getEncryptionInfo()

setEncryptionInfo

public void setEncryptionInfo(EncryptionInfo encryptionInfo)

clone

public Decryptor clone()
                throws CloneNotSupportedException

Throws:

CloneNotSupportedException