com.sun.pdfview.decrypt

## Class IdentityDecrypter

- java.lang.Object
- - com.sun.pdfview.decrypt.IdentityDecrypter

All Implemented Interfaces:
  PDFDecrypter

    public class IdentityDecrypter
    extends java.lang.Object
    implements PDFDecrypter

Performs identity decryption; that is, inputs aren't encrypted and are returned right back.

### Constructor Summary

Constructors
Constructor and Description
`IdentityDecrypter()`

### Method Summary

Methods
`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`.
`static IdentityDecrypter` `getInstance()`
`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

#### IdentityDecrypter

    public IdentityDecrypter()

### 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)

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

#### getInstance

    public static IdentityDecrypter getInstance()

#### 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