Class CryptFilterDecrypter

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

public class CryptFilterDecrypter extends 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.
  • Field Details

    • decrypters

      private Map<String,PDFDecrypter> decrypters
      Maps from crypt filter names to their corresponding decrypters
    • defaultStreamDecrypter

      private PDFDecrypter defaultStreamDecrypter
      The default decrypter for stream content
    • defaultStringDecrypter

      private PDFDecrypter defaultStringDecrypter
      The default decrypter for string content
  • Constructor Details

    • CryptFilterDecrypter

      public CryptFilterDecrypter(Map<String,PDFDecrypter> decrypters, String defaultStreamCryptName, 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 Details

    • decryptBuffer

      public ByteBuffer decryptBuffer(String cryptFilterName, PDFObject streamObj, 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 String decryptString(int objNum, int objGen, 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
    • 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