at.gv.egiz.pdfas.impl.vfilter
Class VerificationFilterParametersImpl

java.lang.Object
  at.gv.egiz.pdfas.impl.vfilter.VerificationFilterParametersImpl

All Implemented Interfaces:

Serializable, VerificationFilterParameters

public class VerificationFilterParametersImpl

extends Object

implements VerificationFilterParameters, Serializable

Author:

wprinz

See Also:

Serialized Form

Field Summary

protected boolean	assumeOnlySignatureUpdateBlocks
protected boolean	extractBinarySignaturesOnly
protected boolean	scanForOldSignatures

Constructor Summary

VerificationFilterParametersImpl(boolean extractBinarySignaturesOnly, boolean assumeOnlySignatureUpdateBlocks, boolean scanForOldSignatures)

Method Summary

boolean	assumeOnlySignatureUpdateBlocks() Tells the VerificationFilter to assume that there are only singatures (and their Incremental Update blocks) younger than the original document.
boolean	extractBinarySignaturesOnly() Tells the VerificationFilter to extract binary signatures only.
boolean	scanForOldSignatures() Tells the VerificationFilter so scan for old signatures in the rest text.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

extractBinarySignaturesOnly

protected boolean extractBinarySignaturesOnly

assumeOnlySignatureUpdateBlocks

protected boolean assumeOnlySignatureUpdateBlocks

scanForOldSignatures

protected boolean scanForOldSignatures

Constructor Detail

VerificationFilterParametersImpl

public VerificationFilterParametersImpl(boolean extractBinarySignaturesOnly,
                                        boolean assumeOnlySignatureUpdateBlocks,
                                        boolean scanForOldSignatures)

Method Detail

extractBinarySignaturesOnly

public boolean extractBinarySignaturesOnly()

Description copied from interface: VerificationFilterParameters

Tells the VerificationFilter to extract binary signatures only.

Not scanning for textual signatures allows the algorithm to skip text extraction and signature extraction, which are both time and memory intensive processes.

Specified by:

extractBinarySignaturesOnly in interface VerificationFilterParameters

Returns:

Returns true if the VerificationFilter should extract binary signatures only.

See Also:

VerificationFilterParameters.extractBinarySignaturesOnly()

assumeOnlySignatureUpdateBlocks

public boolean assumeOnlySignatureUpdateBlocks()

Description copied from interface: VerificationFilterParameters

Tells the VerificationFilter to assume that there are only singatures (and their Incremental Update blocks) younger than the original document.

This is equivalent to saying that the document was not updated using an Incremental update block other than a signature after being singed. The incremental update blocks after the original document contain only signatures (either text or binary).

This is equivalent to saying that there exists no Incremental Update block that would render a text signature before it invalid.

Under this assumption, the process of finding all text signatures simplifies to one text extraction of the whole document and one signature extraction. This is of course a massive performance gain.

Actually the algorithm performs a text extraction of the whole document not including trailing binary signature Incremental Update blocks. This means that if a the last n Incremental Update blocks of a document are binary, there is no use extract text from them.

Note that if there are Incremental Update blocks with text after a signature thus this assumption does not hold the signatures older than this block will break.

Specified by:

assumeOnlySignatureUpdateBlocks in interface VerificationFilterParameters

Returns:

Returns true if the Verification filter should assume that there are only signature blocks after the original document.

See Also:

VerificationFilterParameters.assumeOnlySignatureUpdateBlocks()

scanForOldSignatures

public boolean scanForOldSignatures()

Description copied from interface: VerificationFilterParameters

Tells the VerificationFilter so scan for old signatures in the rest text.

The rest text is the text of the oldest text signature or the original document text if there is no text signature.

Specified by:

scanForOldSignatures in interface VerificationFilterParameters

Returns:

Returns true if the VerificationFilter should scan for old text signatures in the rest text.

See Also:

VerificationFilterParameters.scanForOldSignatures()

toString

public String toString()

See Also:

Object.toString()