org.icepdf.core.pobjects.security
Class CryptFilter

java.lang.Object
  org.icepdf.core.pobjects.Dictionary
      org.icepdf.core.pobjects.security.CryptFilter

public class CryptFilter
extends Dictionary

PDF 1.5 introduces crypt filters, which provide finer granularity control of encryption within a PDF file. The use of crypt filters involves the following structures:

• The encryption dictionary (see Table 20) contains entries that enumerate the crypt filters in the document (CF) and specify which ones are used by default to decrypt all the streams (StmF) and strings (StrF) in the document. In addition, the value of the V entry shall be 4 to use crypt filters.
• Each crypt filter specified in the CF entry of the encryption dictionary shall be represented by a crypt filter dictionary, whose entries are shown in Table 25.
• A stream filter type, the Crypt filter (see 7.4.10, "Crypt Filter") can be specified for any stream in the document to override the default filter for streams. A conforming reader shall provide a standard Identity filter which shall pass the data unchanged (see Table 26) to allow specific streams, such as document metadata, to be unencrypted in an otherwise encrypted document. The stream's DecodeParms entry shall contain a Crypt filter decode parameters dictionary (see Table 14) whose Name entry specifies the particular crypt filter to be used (if missing, Identity is used). Different streams may specify different crypt filters.

Authorization to decrypt a stream shall always be obtained before the stream can be accessed. This typically occurs when the document is opened, as specified by a value of DocOpen for the AuthEvent entry in the crypt filter dictionary. Conforming readers and security handlers shall treat any attempt to access a stream for which authorization has failed as an error. AuthEvent can also be EFOpen, which indicates the presence of an embedded file that is encrypted with a crypt filter that may be different from the crypt filters used by default to encrypt strings and streams in the document.

Field Summary

java.util.HashMap<Name,CryptFilterEntry>

cryptFilters

Fields inherited from class org.icepdf.core.pobjects.Dictionary

entries, inited, isDeleted, isNew, library, SUBTYPE_KEY, TYPE_KEY

Constructor Summary

CryptFilter(Library library, java.util.Hashtable entries)

Method Summary

CryptFilterEntry

getCryptFilterByName(Name cryptFilterName) Gets a crypt filters definition as defined in its dictionary by name.

Methods inherited from class org.icepdf.core.pobjects.Dictionary

getEntries, getFloat, getInt, getLibrary, getNumber, getObject, getObject, getPObjectReference, init, isDeleted, isNew, setDeleted, setNew, setPObjectReference, toString

Methods inherited from class java.lang.Object

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

Field Detail

cryptFilters

public java.util.HashMap<Name,CryptFilterEntry> cryptFilters

Constructor Detail

CryptFilter

public CryptFilter(Library library,
                   java.util.Hashtable entries)

Method Detail

getCryptFilterByName

public CryptFilterEntry getCryptFilterByName(Name cryptFilterName)

Gets a crypt filters definition as defined in its dictionary by name.

Parameters:

cryptFilterName - name of crypt filter to find.

Returns:

crypt filter entry specified by the given name. if not found null is returned.