org.apache.poi.poifs.crypt.cryptoapi

Class CryptoAPIDecryptor

java.lang.Object

org.apache.poi.poifs.crypt.Decryptor

org.apache.poi.poifs.crypt.cryptoapi.CryptoAPIDecryptor

public class CryptoAPIDecryptor
extends Decryptor

Field Summary

Fields inherited from class org.apache.poi.poifs.crypt.Decryptor

DEFAULT_PASSWORD, DEFAULT_POIFS_ENTRY

Method Summary

Modifier and Type	Method and Description
java.io.InputStream	getDataStream(DirectoryNode dir) Decrypt the Document-/SummaryInformation and other optionally streams.
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 decryption
boolean	verifyPassword(java.lang.String password)

Methods inherited from class org.apache.poi.poifs.crypt.Decryptor

getDataStream, getDataStream, getInstance, getIntegrityHmacKey, getIntegrityHmacValue, getSecretKey, getVerifier

Methods inherited from class java.lang.Object

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

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

Initializes a cipher object for a given block index for decryption

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

getDataStream

public java.io.InputStream getDataStream(DirectoryNode dir)
                                  throws java.io.IOException,
                                         java.security.GeneralSecurityException

Decrypt the Document-/SummaryInformation and other optionally streams. Opposed to other crypto modes, cryptoapi is record based and can't be used to stream-decrypt a whole file

Specified by:

getDataStream in class Decryptor

Parameters:

dir - the node to read from

Returns:

decrypted stream

Throws:

java.io.IOException

java.security.GeneralSecurityException

See Also:

2.3.5.4 RC4 CryptoAPI Encrypted Summary Stream

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:

the length of the stream returned by getDataStream(DirectoryNode)