2 files changed, 177 insertions, 0 deletions
diff --git a/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/framework/vfilter/VerificationFilter.java b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/framework/vfilter/VerificationFilter.java
new file mode 100644
index 0000000..58422d2
--- /dev/null
+++ b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/framework/vfilter/VerificationFilter.java
@@ -0,0 +1,72 @@
+/**
+ * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
+ * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
+ * joint initiative of the Federal Chancellery Austria and Graz University of
+ * Technology.
+ *
+ * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
+ * the European Commission - subsequent versions of the EUPL (the "Licence");
+ * You may not use this work except in compliance with the Licence.
+ * You may obtain a copy of the Licence at:
+ * http://www.osor.eu/eupl/
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the Licence is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the Licence for the specific language governing permissions and
+ * limitations under the Licence.
+ *
+ * This product combines work with different licenses. See the "NOTICE" text
+ * file for details on the various modules and licenses.
+ * The "NOTICE" text file is part of the distribution. Any derivative works
+ * that you distribute must include a readable copy of the "NOTICE" text file.
+ */
+package at.gv.egiz.pdfas.framework.vfilter;
+
+import java.util.List;
+
+import at.gv.egiz.pdfas.exceptions.framework.VerificationFilterException;
+import at.gv.egiz.pdfas.framework.input.PdfDataSource;
+import at.gv.egiz.pdfas.framework.input.TextDataSource;
+
+/**
+ * Extracts all signatures from a given PDF document or text.
+ * 
+ * @see VerificationFilterParameters
+ * 
+ * @author wprinz
+ */
+public interface VerificationFilter
+{
+
+  /**
+   * Extracts the signatures from the given PDF.
+   * 
+   * @param pdf
+   *          The PDF.
+   * @param blocks
+   *          The List of Incremental Update blocks. Usually this comes from a
+   *          preprocessing step.
+   * @param parameters
+   *          The algorithm parameters.
+   * @return Returns a List of SignatureHolders containing the signatures. May
+   *         be empty in case no signatures have been found.
+   * @throws VerificationFilterException
+   *           Thrown if something goes wrong.
+   */
+  public List extractSignatureHolders(PdfDataSource pdf, List blocks, VerificationFilterParameters parameters) throws VerificationFilterException;
+
+  /**
+   * Extracts the text signatures from the given free-text.
+   * 
+   * @param text
+   *          The free-text.
+   * @param parameters
+   *          The algorithm parameters.
+   * @return Returns a List of SignatureHolders containing the signatures. May
+   *         be empty in case no signatures have been found.
+   * @throws VerificationFilterException
+   *           Thrown if something goes wrong.
+   */
+  public List extractSignaturHolders(TextDataSource text, VerificationFilterParameters parameters) throws VerificationFilterException;
+}
diff --git a/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/framework/vfilter/VerificationFilterParameters.java b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/framework/vfilter/VerificationFilterParameters.java
new file mode 100644
index 0000000..cf99086
--- /dev/null
+++ b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/framework/vfilter/VerificationFilterParameters.java
@@ -0,0 +1,105 @@
+/**
+ * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
+ * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
+ * joint initiative of the Federal Chancellery Austria and Graz University of
+ * Technology.
+ *
+ * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
+ * the European Commission - subsequent versions of the EUPL (the "Licence");
+ * You may not use this work except in compliance with the Licence.
+ * You may obtain a copy of the Licence at:
+ * http://www.osor.eu/eupl/
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the Licence is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the Licence for the specific language governing permissions and
+ * limitations under the Licence.
+ *
+ * This product combines work with different licenses. See the "NOTICE" text
+ * file for details on the various modules and licenses.
+ * The "NOTICE" text file is part of the distribution. Any derivative works
+ * that you distribute must include a readable copy of the "NOTICE" text file.
+ */
+package at.gv.egiz.pdfas.framework.vfilter;
+
+/**
+ * The parameters of the VerificationFilter algorithm.
+ * 
+ * @author wprinz
+ */
+public interface VerificationFilterParameters
+{
+
+  /**
+   * Tells the VerificationFilter to extract binary signatures only.
+   * 
+   * <p>
+   * Not scanning for textual signatures allows the algorithm to skip text
+   * extraction and signature extraction, which are both time and memory
+   * intensive processes.
+   * </p>
+   * 
+   * @return Returns true if the VerificationFilter should extract binary
+   *         signatures only.
+   */
+  public boolean extractBinarySignaturesOnly();
+
+  /**
+   * Tells the VerificationFilter to assume that there are only singatures (and
+   * their Incremental Update blocks) younger than the original document.
+   * 
+   * <p>
+   * 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).
+   * </p>
+   * <p>
+   * This is equivalent to saying that there exists no Incremental Update block
+   * that would render a text signature before it invalid.
+   * </p>
+   * <p>
+   * 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.
+   * </p>
+   * <p>
+   * 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.
+   * </p>
+   * <p>
+   * 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.
+   * </p>
+   * 
+   * @return Returns true if the Verification filter should assume that there
+   *         are only signature blocks after the original document.
+   */
+  public boolean assumeOnlySignatureUpdateBlocks();
+
+  /**
+   * Tells the VerificationFilter so scan for old signatures in the rest text.
+   * 
+   * <p>
+   * The rest text is the text of the oldest text signature or the original
+   * document text if there is no text signature.
+   * </p>
+   * 
+   * @return Returns true if the VerificationFilter should scan for old text
+   *         signatures in the rest text.
+   */
+  public boolean scanForOldSignatures();
+  
+  /**
+   * Return value that tell if the document has been corrected before verification.
+   * 
+   * @return
+   */
+  public boolean hasBeenCorrected();
+  
+  public void setBeenCorrected(boolean corrected);
+}