code: public boolean signatureCoversWholeDocument(String name) {
          getSignatureNames();
          name = getTranslatedFieldName(name);
          if (!sigNames.containsKey(name))
              return false;
          return ((int[])sigNames.get(name))[0] == reader.getFileLength();
      }
docs: Checks is the signature covers the entire document or just part of it.
  
  @param name the signature field name
  @return <CODE>true</CODE> if the signature covers the entire document,
  <CODE>false</CODE> otherwise