at.knowcenter.wag.egov.egiz.pdf
Class BinarySignature

java.lang.Object
  at.knowcenter.wag.egov.egiz.pdf.BinarySignature

public abstract class BinarySignature

extends Object

Contains various extension functions to digitally sign documents.

These functions are used to replace parts of the original Egiz plain text signature mechanism.

Author:

wprinz

Field Summary

static byte[]	BREV_ALG The SIG_ALG brev.
static byte[]	BREV_DAT The date brev.
static byte[]	BREV_ISS The issure brev.
static byte[]	BREV_NIL The nil brev used to define an unrecognized value.
static byte[]	BREV_SID The SIG_ID brev.
static byte[]	BREV_SNR The serial number brev.
static byte[]	BREV_VAL The value brev.
static int	CERTIFICATE_PLACEHOLDER_LENGTH The number of bytes left out for the certificate placeholder.
static com.lowagie.text.pdf.PdfName	EGIZ_BYTERANGES_NAME The PDFName of the byte ranges array.
static com.lowagie.text.pdf.PdfName	EGIZ_CERTIFICATE_NAME The PdfName of the certificate array.
static com.lowagie.text.pdf.PdfName	EGIZ_DATA_NAME The PdfName of the data array that contains various egiz-dict data.
static com.lowagie.text.pdf.PdfName	EGIZ_DICT_NAME The PDFName of the Egiz Dictionary.
static com.lowagie.text.pdf.PdfName	EGIZ_ENCODINGS_NAME The PDFName of the /encodings field in an Egiz Dictionary.
static com.lowagie.text.pdf.PdfName	EGIZ_KZ_NAME The PDFName of the Kennzeichnung attribute.
static com.lowagie.text.pdf.PdfName	EGIZ_ODS_NAME The PDFName of the Original Document Size (ODS) field in an Egiz Dictionary.
static com.lowagie.text.pdf.PdfName	EGIZ_REPLACES_NAME The PDFName of the /replaces field in an Egiz Dictionary.
static com.lowagie.text.pdf.PdfName	EGIZ_TIMESTAMP_NAME The PdfName of the Timestamp
static com.lowagie.text.pdf.PdfName	EGIZ_XOBJ_NAME The PDFName of the Signature XObject field in an Egiz Dictionary.
static byte[]	ENCODING_NIL No explicit encoding.
static byte[]	ENCODING_URL URL encoding.
static byte[]	ENCODING_WIN PDF WinAnsiEncoding.
static byte	LAYOUT_PLACEHOLDER The placeholder character used to fill out Strings in the layout process.
static int	LINE_BREAK_TOLERANCE The tolerance area of the line break algorithm.
protected static org.apache.commons.logging.Log	logger
protected static com.lowagie.text.pdf.PdfNumber	NUMBER_PLACEHOLDER The number placeholder that is used to give numbers a fixed length.
static byte	SIGN_PLACEHOLDER This placeholder is used to fill out holes between the byte ranges before the document is signed.
static int	TIMESTAMP_PLACEHOLDER_LENGTH The number of bytes left out for the timestamp placeholder.

Constructor Summary

BinarySignature()

Method Summary

static byte[]	buildDigest(byte[] data, int length) Builds a digest of the given data.
protected static int	calcNumReps(List replaces) Calculates the number of actual String replaces from a given ReplaceInfo list.
protected static void	createEgizDict(com.lowagie.text.pdf.PdfStamper stamper, com.lowagie.text.pdf.PdfTemplate table_template, IncrementalUpdateInformation iui, List variable_field_definitions, List all_field_definitions, List invisible_field_definitions, String invisibleKZString) Creates the EGIZ Dictionary and adds it to the document.
protected static List	determineKZ(byte[] pdf, int begin, int end, List field_definitions) Determines the Kennzeichnug in the content stream.
protected static List	determineReplacesInContentStream(byte[] pdf, int begin, int end, List field_definitions) Determines the List of ReplaceInfo objects of replaces in the content stream regarding the given field definitions.
static String	extractSignatureTextOnly(com.lowagie.text.pdf.PdfDictionary egiz_dict) Extracts the signature text only.
protected static int	findFirstNotPlaceholder(List strings, int start) Finds the first string after and at the given index not being a placeholder string.
protected static int	findIndex(List strings, byte[] caption) Finds the index of the StringInfo within the StringInfo list that has the given content (caption).
protected static int	getCertificatePlaceholderLength(IncrementalUpdateInformation iui)
static List	getEgizDictChainFromReader(com.lowagie.text.pdf.PdfReader reader) Retrieves the chain of Egiz Dictionaries from the reader.
static com.lowagie.text.pdf.PdfDictionary	getEgizDictFromReader(com.lowagie.text.pdf.PdfReader reader) Retrieves the Egiz Dictionary from the document if present.
static com.lowagie.text.pdf.PdfIndirectReference	getEgizDictIndRefFromReader(com.lowagie.text.pdf.PdfReader reader) Retrieves the Egiz Dictionary's indirect reference from the reader.
protected static int	getLineBreakTolerance(IncrementalUpdateInformation iui)
static int	getOriginalDocumentSizeFromEgizDict(com.lowagie.text.pdf.PdfDictionary egiz_dict) Retrieves the size of the original document from the Egiz Dictionary.
static com.lowagie.text.pdf.PdfDictionary	getPreviousFromEgizDict(com.lowagie.text.pdf.PdfDictionary egiz_dict) Retrieves the previous Egiz dictionary from the given one, if a previous dictionary exists.
protected static int	getTimestampPlaceholderLength(IncrementalUpdateInformation iui)
protected static boolean	isCaption(List strings, int index, byte[] caption)
protected static boolean	isPlaceholder(StringInfo si, byte placeholder) Tells, if the given StringInfo contains only placeholder characters.
static void	markByteRanges(IncrementalUpdateInformation iui) Updates the information in the egiz dictionary to reflect the real offsets of the byte ranges.
static byte[]	prepareDataToSign(byte[] data, List byte_ranges) Fills the holes in the byte ranges with the SIGN_PLACEHOLDER.
static int	readNumber(byte[] pdf, int start_index, int num_digits) Reads an unsigned integer number.
static List	reconstructReplaces(byte[] pdf, byte[][] brevs, StringInfo[] sis, byte[][] encodings) Reconstructs the replaces from the PDF and forms suitable value strings.
static void	replaceCertificate(IncrementalUpdateInformation iui) Replaces the certificate placeholder with the certificate from the signed Signature Object.
static void	replaceNumber(byte[] pdf, int start_index, int number, int num_digits) Replaces a number by the new value.
static void	replacePlaceholders(IncrementalUpdateInformation iui) Replaces the placeholders with values from the signed SignatureObject.
static void	replaceTimestamp(IncrementalUpdateInformation iui) Replaces the timestam placeholder with the timestamp from the signed Signature Object.
static void	restorePlaceholder(byte[] pdf, StringInfo si, byte placeholder) Restores the given String to its placeholder.
static String	retrieveSignableTextFromData(byte[] data, int ods) Retrieves the signable text from the given document.
protected static int	skipStrings(List strings, int index, byte[] caption)
protected static boolean	startsWithCaption(StringInfo si, List field_definitions)
protected static byte[]	typeToBrev(String type) Converts a field name (type) to the corresponding BREV.
static IncrementalUpdateInformation	writeIncrementalUpdate(PdfDataSource original_document, DataSink written_pdf, com.lowagie.text.pdf.PdfPTable pdf_table, String profile, PositioningInstruction pi, List variable_field_definitions, List all_field_definitions, List invisible_field_definitions, String invisibleKZString, TimeStamper timeStamper, SignatorInformation si, SignatureObject so) Signs a document with the given signature table using the Incremental Update method.

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static org.apache.commons.logging.Log logger

LINE_BREAK_TOLERANCE

public static final int LINE_BREAK_TOLERANCE

The tolerance area of the line break algorithm.

See Also:

Placeholder.replacePlaceholderWithTolerance(byte[], List, byte[], int), Constant Field Values

CERTIFICATE_PLACEHOLDER_LENGTH

public static final int CERTIFICATE_PLACEHOLDER_LENGTH

The number of bytes left out for the certificate placeholder.

See Also:

Constant Field Values

TIMESTAMP_PLACEHOLDER_LENGTH

public static final int TIMESTAMP_PLACEHOLDER_LENGTH

The number of bytes left out for the timestamp placeholder.

See Also:

Constant Field Values

LAYOUT_PLACEHOLDER

public static final byte LAYOUT_PLACEHOLDER

The placeholder character used to fill out Strings in the layout process.

See Also:

Constant Field Values

SIGN_PLACEHOLDER

public static final byte SIGN_PLACEHOLDER

This placeholder is used to fill out holes between the byte ranges before the document is signed.

See Also:

Constant Field Values

BREV_NIL

public static final byte[] BREV_NIL

The nil brev used to define an unrecognized value.

BREV_DAT

public static final byte[] BREV_DAT

The date brev.

BREV_ISS

public static final byte[] BREV_ISS

The issure brev.

BREV_SNR

public static final byte[] BREV_SNR

The serial number brev.

BREV_VAL

public static final byte[] BREV_VAL

The value brev.

BREV_SID

public static final byte[] BREV_SID

The SIG_ID brev.

BREV_ALG

public static final byte[] BREV_ALG

The SIG_ALG brev.

ENCODING_NIL

public static final byte[] ENCODING_NIL

No explicit encoding.

ENCODING_WIN

public static final byte[] ENCODING_WIN

PDF WinAnsiEncoding.

ENCODING_URL

public static final byte[] ENCODING_URL

URL encoding.

EGIZ_DICT_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_DICT_NAME

The PDFName of the Egiz Dictionary.

Used to locate and identify the Egiz Dictionary in the document.

EGIZ_ODS_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_ODS_NAME

The PDFName of the Original Document Size (ODS) field in an Egiz Dictionary.

The ODS must be a positive integral number.

EGIZ_KZ_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_KZ_NAME

The PDFName of the Kennzeichnung attribute.

EGIZ_REPLACES_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_REPLACES_NAME

The PDFName of the /replaces field in an Egiz Dictionary.

EGIZ_ENCODINGS_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_ENCODINGS_NAME

The PDFName of the /encodings field in an Egiz Dictionary.

EGIZ_BYTERANGES_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_BYTERANGES_NAME

The PDFName of the byte ranges array.

EGIZ_CERTIFICATE_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_CERTIFICATE_NAME

The PdfName of the certificate array.

EGIZ_TIMESTAMP_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_TIMESTAMP_NAME

The PdfName of the Timestamp

EGIZ_DATA_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_DATA_NAME

The PdfName of the data array that contains various egiz-dict data.

EGIZ_XOBJ_NAME

public static final com.lowagie.text.pdf.PdfName EGIZ_XOBJ_NAME

The PDFName of the Signature XObject field in an Egiz Dictionary.

This must be an indirect reference to the XObject containing the Signature table.

NUMBER_PLACEHOLDER

protected static final com.lowagie.text.pdf.PdfNumber NUMBER_PLACEHOLDER

The number placeholder that is used to give numbers a fixed length.

Constructor Detail

BinarySignature

public BinarySignature()

Method Detail

extractSignatureTextOnly

public static String extractSignatureTextOnly(com.lowagie.text.pdf.PdfDictionary egiz_dict)
                                       throws IOException

Extracts the signature text only.

The signature text is the text of the Signature XObject.

Parameters:

egiz_dict - The Egiz Dictionary.

Returns:

Returns the signature text.

Throws:

IOException

getOriginalDocumentSizeFromEgizDict

public static int getOriginalDocumentSizeFromEgizDict(com.lowagie.text.pdf.PdfDictionary egiz_dict)

Retrieves the size of the original document from the Egiz Dictionary.

Parameters:

egiz_dict - The Egiz Dictionary.

Returns:

Returns the size (in bytes) of the original document.

getPreviousFromEgizDict

public static com.lowagie.text.pdf.PdfDictionary getPreviousFromEgizDict(com.lowagie.text.pdf.PdfDictionary egiz_dict)

Retrieves the previous Egiz dictionary from the given one, if a previous dictionary exists.

Parameters:

egiz_dict - The Egiz Dictionary.

Returns:

Returns the previous Egiz Dictionary, or null if there is none.

getEgizDictFromReader

public static com.lowagie.text.pdf.PdfDictionary getEgizDictFromReader(com.lowagie.text.pdf.PdfReader reader)

Retrieves the Egiz Dictionary from the document if present.

Parameters:

reader - The reader to retrieve the dictionary from.

Returns:

Returns the Egiz Dictionary, if present, or returns null, if no egiz dictionary was found.

getEgizDictIndRefFromReader

public static com.lowagie.text.pdf.PdfIndirectReference getEgizDictIndRefFromReader(com.lowagie.text.pdf.PdfReader reader)

Retrieves the Egiz Dictionary's indirect reference from the reader.

Parameters:

reader - The reader.

Returns:

Returns the indirect reference of the Egiz Dictionary, or null, if none exists.

getEgizDictChainFromReader

public static List getEgizDictChainFromReader(com.lowagie.text.pdf.PdfReader reader)

Retrieves the chain of Egiz Dictionaries from the reader.

The first element in the List will be the top most (oldest) Egiz Dictionary. The last element in the List will be the bottom most (latest) Egiz Dictionary. If the list is empty, no dictionary could be found at all, which means that the document is not digitally signed.

Parameters:

reader - The reader.

Returns:

Returns the List of PdfDictionaries from the document.

buildDigest

public static byte[] buildDigest(byte[] data,
                                 int length)
                          throws PDFDocumentException

Builds a digest of the given data.

Parameters:

data - The data to be digested.

length - The length of the data portion that should be used for digesting. This allows to build the digest only over parts of the data.

Returns:

Returns the created digest.

Throws:

PDFDocumentException - Forwarded exception.

retrieveSignableTextFromData

public static String retrieveSignableTextFromData(byte[] data,
                                                  int ods)

Retrieves the signable text from the given document.

Parameters:

data - The data.

ods - The original document size.

Returns:

Returns the signable text.

prepareDataToSign

public static byte[] prepareDataToSign(byte[] data,
                                       List byte_ranges)

Fills the holes in the byte ranges with the SIGN_PLACEHOLDER.

Parameters:

data - The given byte ranged data.

byte_ranges - The byte ranges.

Returns:

Returns the filled text.

getLineBreakTolerance

protected static int getLineBreakTolerance(IncrementalUpdateInformation iui)
                                    throws PDFDocumentException

Throws:

PDFDocumentException

getCertificatePlaceholderLength

protected static int getCertificatePlaceholderLength(IncrementalUpdateInformation iui)
                                              throws SettingNotFoundException

Throws:

SettingNotFoundException

getTimestampPlaceholderLength

protected static int getTimestampPlaceholderLength(IncrementalUpdateInformation iui)
                                            throws SettingNotFoundException

Throws:

SettingNotFoundException

writeIncrementalUpdate

public static IncrementalUpdateInformation writeIncrementalUpdate(PdfDataSource original_document,
                                                                  DataSink written_pdf,
                                                                  com.lowagie.text.pdf.PdfPTable pdf_table,
                                                                  String profile,
                                                                  PositioningInstruction pi,
                                                                  List variable_field_definitions,
                                                                  List all_field_definitions,
                                                                  List invisible_field_definitions,
                                                                  String invisibleKZString,
                                                                  TimeStamper timeStamper,
                                                                  SignatorInformation si,
                                                                  SignatureObject so)
                                                           throws PresentableException

Signs a document with the given signature table using the Incremental Update method.

The table containing the signature text will be appended. As specified by the parameters, the signature will be appended to the last page, or a plain new page will be created for the signature to hold.

The table will be completely wrapped by an XObject, which will also be indirectly referenced by the Egiz Dictionary. This will ease the verification process.

An Egiz Dictionary will be added to the new document that contains information about the signature. Basically the size of the original document and the reference of the signature table.

Parameters:

original_document - The original document.

pdf_table - The PdfPTable that contains the signature block.

pi - The PositioningInstruction telling the algorithm where to place the signature block.

invisible_field_definitions - List of invisible field definitions to be added to the egiz dict. May be null or empty, if there are no invisible fields.

invisibleKZString - If not null, thins String is the KZ String to be written into the /Data array.

Returns:

Returns the new document.

Throws:

PresentableException - Forwarded exception.

createEgizDict

protected static void createEgizDict(com.lowagie.text.pdf.PdfStamper stamper,
                                     com.lowagie.text.pdf.PdfTemplate table_template,
                                     IncrementalUpdateInformation iui,
                                     List variable_field_definitions,
                                     List all_field_definitions,
                                     List invisible_field_definitions,
                                     String invisibleKZString)
                              throws IOException,
                                     SettingNotFoundException,
                                     CaptionNotFoundException

Creates the EGIZ Dictionary and adds it to the document.

Parameters:

stamper - The PdfStamper.

table_template - The Template of the Signature block.

iui - The IncrementalUpdateInformation.

variable_field_definitions - The field definitions.

Throws:

IOException

SettingNotFoundException

CaptionNotFoundException

typeToBrev

protected static byte[] typeToBrev(String type)

Converts a field name (type) to the corresponding BREV.

Parameters:

type - The field name (type).

Returns:

Returns the corresponding BREV, or BREV_NIL if the type is not recognized.

markByteRanges

public static void markByteRanges(IncrementalUpdateInformation iui)
                           throws PDFDocumentException

Updates the information in the egiz dictionary to reflect the real offsets of the byte ranges.

This replaces the "dummy numbers" in the egiz dictionary with the correct values.

Parameters:

iui - The IncrementalUpdateInformation.

Throws:

PDFDocumentException

replaceCertificate

public static void replaceCertificate(IncrementalUpdateInformation iui)
                               throws PDFDocumentException

Replaces the certificate placeholder with the certificate from the signed Signature Object.

Parameters:

iui - The IncrementalUpdateInformation.

Throws:

PDFDocumentException

replaceTimestamp

public static void replaceTimestamp(IncrementalUpdateInformation iui)
                             throws PDFDocumentException

Replaces the timestam placeholder with the timestamp from the signed Signature Object.

Parameters:

iui - The IncrementalUpdateInformation.

Throws:

PDFDocumentException

replacePlaceholders

public static void replacePlaceholders(IncrementalUpdateInformation iui)
                                throws PDFDocumentException

Replaces the placeholders with values from the signed SignatureObject.

Parameters:

iui - The IncrementalUpdateInformation.

Throws:

PDFDocumentException

calcNumReps

protected static int calcNumReps(List replaces)

Calculates the number of actual String replaces from a given ReplaceInfo list.

This is used to determine the number of actual replaces that has to be carried out. Accordingly to this number, entries in the dictionary are created.

Parameters:

replaces - The ReplaceInfo list.

Returns:

Returns the number of string replaces.

determineReplacesInContentStream

protected static List determineReplacesInContentStream(byte[] pdf,
                                                       int begin,
                                                       int end,
                                                       List field_definitions)
                                                throws CaptionNotFoundException

Determines the List of ReplaceInfo objects of replaces in the content stream regarding the given field definitions.

This method collects all variable String fields in a content stream and orders them according to their start offset.

Parameters:

pdf - The PDF.

begin - The start of the content stream.

end - The end of the content stream.

field_definitions - The field definitions that are counceled to find out which and where varaible strings are.

Returns:

Returns the list of ReplaceInfo objects specifying the variable areas.

Throws:

CaptionNotFoundException

determineKZ

protected static List determineKZ(byte[] pdf,
                                  int begin,
                                  int end,
                                  List field_definitions)
                           throws SettingNotFoundException

Determines the Kennzeichnug in the content stream.

Parameters:

pdf - The PDF.

begin - The start of the content stream.

end - The end of the content stream.

field_definitions - The field definitions.

Returns:

Returns the List of StringInfo objects representing the KZ field.

Throws:

SettingNotFoundException - F.e.

findIndex

protected static int findIndex(List strings,
                               byte[] caption)

Finds the index of the StringInfo within the StringInfo list that has the given content (caption).

Parameters:

strings - The list of StringInfos.

caption - The text to be matched to the strings.

Returns:

Returns the index of the found string, or -1 if no string matched.

isCaption

protected static boolean isCaption(List strings,
                                   int index,
                                   byte[] caption)

skipStrings

protected static int skipStrings(List strings,
                                 int index,
                                 byte[] caption)

isPlaceholder

protected static boolean isPlaceholder(StringInfo si,
                                       byte placeholder)

Tells, if the given StringInfo contains only placeholder characters.

Parameters:

si - The StringInfo.

placeholder - The placeholder character.

Returns:

Returns true, if the string contains only the given placeholder characters, false otherwise.

startsWithCaption

protected static boolean startsWithCaption(StringInfo si,
                                           List field_definitions)

findFirstNotPlaceholder

protected static int findFirstNotPlaceholder(List strings,
                                             int start)

Finds the first string after and at the given index not being a placeholder string.

Parameters:

strings - The list of StringInfos.

start - The index where to start the search.

Returns:

Returns the index of the first not placeholder string, or strings.size() if no more non placeholder strings could be found.

restorePlaceholder

public static void restorePlaceholder(byte[] pdf,
                                      StringInfo si,
                                      byte placeholder)

Restores the given String to its placeholder.

Parameters:

pdf - The PDF.

si - The string.

placeholder - The placeholder the string should be filled with.

reconstructReplaces

public static List reconstructReplaces(byte[] pdf,
                                       byte[][] brevs,
                                       StringInfo[] sis,
                                       byte[][] encodings)
                                throws PDFDocumentException

Reconstructs the replaces from the PDF and forms suitable value strings.

Parameters:

pdf - The PDF.

brevs - The brevs.

sis - The StringInfo objects of the strings.

Returns:

Returns the List of ReplaceInfo objects containing the restored values.

Throws:

PDFDocumentException

readNumber

public static int readNumber(byte[] pdf,
                             int start_index,
                             int num_digits)

Reads an unsigned integer number.

Parameters:

pdf - The PDF.

start_index - The start index of the number.

num_digits - The number of digits.

Returns:

Returns the read number.

replaceNumber

public static void replaceNumber(byte[] pdf,
                                 int start_index,
                                 int number,
                                 int num_digits)

Replaces a number by the new value.

Parameters:

pdf - The PDF.

start_index - The start index of the number.

number - The new number.

num_digits - The number of digits.