com.sun.pdfview.decrypt
Class CryptFilterDecrypter

java.lang.Object
  extended by com.sun.pdfview.decrypt.CryptFilterDecrypter
All Implemented Interfaces:
PDFDecrypter

public class CryptFilterDecrypter
extends java.lang.Object
implements PDFDecrypter

Implements Version 4 standard decryption, whereby the Encrypt dictionary contains a list of named 'crypt filters', each of which is the equivalent of a PDFDecrypter. In addition to this list of crypt filters, the name of the filter to use for streams and the default filter to use for strings is specified. Requests to decode a stream with a named decrypter (typically Identity) instead of the default decrypter are honoured.


Constructor Summary
CryptFilterDecrypter(java.util.Map<java.lang.String,PDFDecrypter> decrypters, java.lang.String defaultStreamCryptName, java.lang.String defaultStringCryptName)
          Class constructor
 
Method Summary
 java.nio.ByteBuffer decryptBuffer(java.lang.String cryptFilterName, PDFObject streamObj, java.nio.ByteBuffer streamBuf)
          Decrypt a buffer of data
 java.lang.String decryptString(int objNum, int objGen, java.lang.String inputBasicString)
          Decrypt a basic string.
 boolean isEncryptionPresent()
          Determine whether this actually applies a decryption other than identity decryption.
 boolean isEncryptionPresent(java.lang.String cryptFilterName)
          Determines whether decryption applies for a given crypt filter name
 boolean isOwnerAuthorised()
          Determine whether the password known by the decrypter indicates that the user is the owner of the document.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

CryptFilterDecrypter

public CryptFilterDecrypter(java.util.Map<java.lang.String,PDFDecrypter> decrypters,
                            java.lang.String defaultStreamCryptName,
                            java.lang.String defaultStringCryptName)
                     throws PDFParseException
Class constructor

Parameters:
decrypters - a map of crypt filter names to their corresponding decrypters. Must already contain the Identity filter.
defaultStreamCryptName - the crypt filter name of the default stream decrypter
defaultStringCryptName - the crypt filter name of the default string decrypter
Throws:
PDFParseException - if one of the named defaults is not present in decrypters
Method Detail

decryptBuffer

public java.nio.ByteBuffer decryptBuffer(java.lang.String cryptFilterName,
                                         PDFObject streamObj,
                                         java.nio.ByteBuffer streamBuf)
                                  throws PDFParseException
Description copied from interface: PDFDecrypter
Decrypt a buffer of data

Specified by:
decryptBuffer in interface PDFDecrypter
Parameters:
cryptFilterName - the name of the crypt filter, if V4 encryption is being used, where individual crypt filters may be specified for individual streams. If encryption is not using V4 encryption (indicated by V=4 in the Encrypt dictionary) then this must be null. Null may also be specified with V4 encryption to indicate that the default filter should be used.
streamObj - the object whose stream is being decrypted. The containing object's number and generation contribute to the key used for stream encrypted with the document's default encryption, so this is typically required. Should be null only if a cryptFilterName is specified, as objects with specific stream filters use the general document key, rather than a stream-specific key.
streamBuf - the buffer to decrypt
Returns:
a buffer containing the decrypted stream, positioned at its beginning; will only be the same buffer as streamBuf if the identity decrypter is being used
Throws:
PDFParseException - if the named crypt filter does not exist, or if a crypt filter is named when named crypt filters are not supported. Problems due to incorrect passwords are revealed prior to this point.

decryptString

public java.lang.String decryptString(int objNum,
                                      int objGen,
                                      java.lang.String inputBasicString)
                               throws PDFParseException
Description copied from interface: PDFDecrypter
Decrypt a basic string.

Specified by:
decryptString in interface PDFDecrypter
Parameters:
objNum - the object number of the containing object
objGen - the generation number of the containing object
inputBasicString - the string to be decrypted
Returns:
the decrypted string
Throws:
PDFParseException - if the named crypt filter does not exist, or if a crypt filter is named when named crypt filters are not supported. Problems due to incorrect passwords are revealed prior to this point.

isEncryptionPresent

public boolean isEncryptionPresent()
Description copied from interface: PDFDecrypter
Determine whether this actually applies a decryption other than identity decryption.

Specified by:
isEncryptionPresent in interface PDFDecrypter
Returns:
whether encryption is present

isEncryptionPresent

public boolean isEncryptionPresent(java.lang.String cryptFilterName)
Description copied from interface: PDFDecrypter
Determines whether decryption applies for a given crypt filter name

Specified by:
isEncryptionPresent in interface PDFDecrypter
Parameters:
cryptFilterName - the crypt filter name
Returns:
whether the given crypt filter decrypts or not

isOwnerAuthorised

public boolean isOwnerAuthorised()
Description copied from interface: PDFDecrypter
Determine whether the password known by the decrypter indicates that the user is the owner of the document. Can be used, in conjunction with PDFDecrypter.isEncryptionPresent() to determine whether any permissions apply.

Specified by:
isOwnerAuthorised in interface PDFDecrypter
Returns:
whether owner authentication is being used to decrypt the document