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Check whether a signature indeed covers a whole document. Add some te…
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…sts.

Introduce ContentsChecker. Refactor SignatureUtil.

DEVSIX-2422
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@ars18wrw @iText-CI
ars18wrw authored and iText-CI committed Nov 29, 2018
1 parent 6cebf2d commit 610bd4b
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Showing 13 changed files with 262 additions and 58 deletions.
52 changes: 28 additions & 24 deletions kernel/src/main/java/com/itextpdf/kernel/pdf/PdfReader.java
View file
Expand Up @@ -607,6 +607,33 @@ protected PdfObject readObject(boolean readAsDirect) throws IOException {
return readObject(readAsDirect, false);
}

protected PdfObject readReference(boolean readAsDirect) {
int num = tokens.getObjNr();
PdfXrefTable table = pdfDocument.getXref();
PdfIndirectReference reference = table.get(num);
if (reference != null) {
if (reference.isFree()) {
Logger logger = LoggerFactory.getLogger(PdfReader.class);
logger.warn(MessageFormatUtil.format(LogMessageConstant.INVALID_INDIRECT_REFERENCE, tokens.getObjNr(), tokens.getGenNr()));
return createPdfNullInstance(readAsDirect);
}
if (reference.getGenNumber() != tokens.getGenNr()) {
if (fixedXref) {
Logger logger = LoggerFactory.getLogger(PdfReader.class);
logger.warn(MessageFormatUtil.format(LogMessageConstant.INVALID_INDIRECT_REFERENCE, tokens.getObjNr(), tokens.getGenNr()));
return createPdfNullInstance(readAsDirect);
} else {
throw new PdfException(PdfException.InvalidIndirectReference1,
MessageFormatUtil.format("{0} {1} R", reference.getObjNumber(), reference.getGenNumber()));
}
}
} else {
reference = table.add((PdfIndirectReference) new PdfIndirectReference(pdfDocument,
num, tokens.getGenNr(), 0).setState(PdfObject.READING));
}
return reference;
}

protected PdfObject readObject(boolean readAsDirect, boolean objStm) throws IOException {
tokens.nextValidToken();
PdfTokenizer.TokenType type = tokens.getTokenType();
Expand Down Expand Up @@ -650,30 +677,7 @@ protected PdfObject readObject(boolean readAsDirect, boolean objStm) throws IOEx
case Name:
return readPdfName(readAsDirect);
case Ref:
int num = tokens.getObjNr();
PdfXrefTable table = pdfDocument.getXref();
PdfIndirectReference reference = table.get(num);
if (reference != null) {
if (reference.isFree()) {
Logger logger = LoggerFactory.getLogger(PdfReader.class);
logger.warn(MessageFormatUtil.format(LogMessageConstant.INVALID_INDIRECT_REFERENCE, tokens.getObjNr(), tokens.getGenNr()));
return createPdfNullInstance(readAsDirect);
}
if (reference.getGenNumber() != tokens.getGenNr()) {
if (fixedXref) {
Logger logger = LoggerFactory.getLogger(PdfReader.class);
logger.warn(MessageFormatUtil.format(LogMessageConstant.INVALID_INDIRECT_REFERENCE, tokens.getObjNr(), tokens.getGenNr()));
return createPdfNullInstance(readAsDirect);
} else {
throw new PdfException(PdfException.InvalidIndirectReference1,
MessageFormatUtil.format("{0} {1} R", reference.getObjNumber(), reference.getGenNumber()));
}
}
} else {
reference = table.add((PdfIndirectReference) new PdfIndirectReference(pdfDocument,
num, tokens.getGenNr(), 0).setState(PdfObject.READING));
}
return reference;
return readReference(readAsDirect);
case EndOfFile:
throw new PdfException(PdfException.UnexpectedEndOfFile);
default:
Expand Down
179 changes: 145 additions & 34 deletions sign/src/main/java/com/itextpdf/signatures/SignatureUtil.java
View file
Expand Up @@ -46,6 +46,8 @@ This file is part of the iText (R) project.
import com.itextpdf.forms.PdfAcroForm;
import com.itextpdf.forms.fields.PdfFormField;
import com.itextpdf.io.font.PdfEncodings;
import com.itextpdf.io.source.IRandomAccessSource;
import com.itextpdf.io.source.PdfTokenizer;
import com.itextpdf.io.source.RASInputStream;
import com.itextpdf.io.source.RandomAccessFileOrArray;
import com.itextpdf.io.source.RandomAccessSourceFactory;
Expand All @@ -56,6 +58,9 @@ This file is part of the iText (R) project.
import com.itextpdf.kernel.pdf.PdfDictionary;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfName;
import com.itextpdf.kernel.pdf.PdfNull;
import com.itextpdf.kernel.pdf.PdfObject;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfString;

import java.io.IOException;
Expand All @@ -80,6 +85,24 @@ public class SignatureUtil {
private List<String> orderedSignatureNames;
private int totalRevisions;

/**
* Converts a {@link com.itextpdf.kernel.pdf.PdfArray} to an array of longs
*
* @param pdfArray PdfArray to be converted
* @return long[] containing the PdfArray values
* @deprecated Will be removed in 7.2. Use {@link PdfArray#toLongArray()} instead
*/
@Deprecated
public static long[] asLongArray(PdfArray pdfArray) {
long[] rslt = new long[pdfArray.size()];

for (int k = 0; k < rslt.length; ++k) {
rslt[k] = pdfArray.getAsNumber(k).longValue();
}

return rslt;
}

/**
* Creates a SignatureUtil instance. Sets the acroForm field to the acroForm in the PdfDocument.
* iText will create a new AcroForm if the PdfDocument doesn't contain one.
Expand Down Expand Up @@ -107,7 +130,7 @@ public PdfPKCS7 verifySignature(String name) {
* Verifies a signature. Further verification can be done on the returned
* {@link PdfPKCS7} object.
*
* @param name the signature field name
* @param name the signature field name
* @param provider the provider or null for the default provider
* @return PdfPKCS7 object to continue the verification
*/
Expand All @@ -124,8 +147,7 @@ public PdfPKCS7 verifySignature(String name, String provider) {
if (cert == null)
cert = signature.getPdfObject().getAsArray(PdfName.Cert).getAsString(0);
pk = new PdfPKCS7(PdfEncodings.convertToBytes(contents.getValue(), null), cert.getValueBytes(), provider);
}
else
} else
pk = new PdfPKCS7(PdfEncodings.convertToBytes(contents.getValue(), null), sub, provider);
updateByteRange(pk, signature);
PdfString date = signature.getDate();
Expand All @@ -140,8 +162,7 @@ public PdfPKCS7 verifySignature(String name, String provider) {
if (location != null)
pk.setLocation(location);
return pk;
}
catch (Exception e) {
} catch (Exception e) {
throw new PdfException(e);
}
}
Expand Down Expand Up @@ -179,8 +200,7 @@ private void updateByteRange(PdfPKCS7 pkcs7, PdfSignature signature) {
while ((rd = rg.read(buf, 0, buf.length)) > 0) {
pkcs7.update(buf, 0, rd);
}
}
catch (Exception e) {
} catch (Exception e) {
throw new PdfException(e);
} finally {
try {
Expand Down Expand Up @@ -234,13 +254,12 @@ public int getTotalRevisions() {
return totalRevisions;
}


public int getRevision(String field) {
getSignatureNames();
field = getTranslatedFieldName(field);
if (!sigNames.containsKey(field))
return 0;
return sigNames.get(field)[1];
return sigNames.get(field)[1];
}

public String getTranslatedFieldName(String name) {
Expand Down Expand Up @@ -269,7 +288,7 @@ public InputStream extractRevision(String field) throws IOException {
}

/**
* Checks if the signature covers the entire document or just part of it.
* Checks if the signature covers the entire document (except for signature's Contents) or just a part of it.
*
* @param name the signature field name
* @return true if the signature covers the entire document, false if it doesn't
Expand All @@ -279,7 +298,8 @@ public boolean signatureCoversWholeDocument(String name) {
if (!sigNames.containsKey(name))
return false;
try {
return sigNames.get(name)[0] == document.getReader().getFileLength();
ContentsChecker signatureReader = new ContentsChecker(document.getReader().getSafeFile().createSourceView());
return signatureReader.checkWhetherSignatureCoversWholeDocument(acroForm.getField(name));
} catch (IOException e) {
throw new PdfException(e);
}
Expand All @@ -295,24 +315,6 @@ public boolean doesSignatureFieldExist(String name) {
return getBlankSignatureNames().contains(name) || getSignatureNames().contains(name);
}

/**
* Converts a {@link com.itextpdf.kernel.pdf.PdfArray} to an array of longs
*
* @param pdfArray PdfArray to be converted
* @return long[] containing the PdfArray values
* @deprecated Will be removed in 7.2. Use {@link PdfArray#toLongArray()} instead
*/
@Deprecated
public static long[] asLongArray(PdfArray pdfArray) {
long[] rslt = new long[pdfArray.size()];

for (int k = 0; k < rslt.length; ++k) {
rslt[k] = pdfArray.getAsNumber(k).longValue();
}

return rslt;
}

private void populateSignatureNames() {
if (acroForm == null) {
return;
Expand Down Expand Up @@ -345,7 +347,7 @@ private void populateSignatureNames() {
Collections.sort(sorter, new SorterComparator());
if (sorter.size() > 0) {
try {
if (((int[])sorter.get(sorter.size() - 1)[1])[0] == document.getReader().getFileLength())
if (((int[]) sorter.get(sorter.size() - 1)[1])[0] == document.getReader().getFileLength())
totalRevisions = sorter.size();
else
totalRevisions = sorter.size() + 1;
Expand All @@ -354,8 +356,8 @@ private void populateSignatureNames() {
}
for (int k = 0; k < sorter.size(); ++k) {
Object[] objs = sorter.get(k);
String name = (String)objs[0];
int[] p = (int[])objs[1];
String name = (String) objs[0];
int[] p = (int[]) objs[1];
p[1] = k + 1;
sigNames.put(name, p);
orderedSignatureNames.add(name);
Expand All @@ -366,9 +368,118 @@ private void populateSignatureNames() {
private static class SorterComparator implements Comparator<Object[]> {
@Override
public int compare(Object[] o1, Object[] o2) {
int n1 = ((int[])o1[1])[0];
int n2 = ((int[])o2[1])[0];
int n1 = ((int[]) o1[1])[0];
int n2 = ((int[]) o2[1])[0];
return n1 - n2;
}
}

private static class ContentsChecker extends PdfReader {

private long contentsStart;
private long contentsEnd;

private int currentLevel = 0;
private int contentsLevel = 1;
private boolean searchInV = true;

private boolean rangeIsCorrect = false;


public ContentsChecker(IRandomAccessSource byteSource) throws IOException {
super(byteSource, null);
}

public boolean checkWhetherSignatureCoversWholeDocument(PdfFormField signatureField) {
rangeIsCorrect = false;
PdfDictionary signature = (PdfDictionary) signatureField.getValue();
int[] byteRange = ((PdfArray) signature.get(PdfName.ByteRange)).toIntArray();
try {
if (4 != byteRange.length || 0 != byteRange[0] || tokens.getSafeFile().length() != byteRange[2] + byteRange[3]) {
return false;
}
} catch (IOException e) {
// That's not expected because if the signature is invalid, it should have already failed
return false;
}

contentsStart = byteRange[1];
contentsEnd = byteRange[2];

long signatureOffset;
if (null != signature.getIndirectReference()) {
signatureOffset = signature.getIndirectReference().getOffset();
searchInV = true;
} else {
signatureOffset = signatureField.getPdfObject().getIndirectReference().getOffset();
searchInV = false;
contentsLevel++;
}

try {
tokens.seek(signatureOffset);
tokens.nextValidToken();
readObject(false, false);
} catch (IOException e) {
// That's not expected because if the signature is invalid, it should have already failed
return false;
}

return rangeIsCorrect;
}

@Override
// The method copies the logic of PdfReader's method.
// Only Contents related checks have been introduced.
protected PdfDictionary readDictionary(boolean objStm) throws IOException {
currentLevel++;
PdfDictionary dic = new PdfDictionary();
while (!rangeIsCorrect) {
tokens.nextValidToken();
if (tokens.getTokenType() == PdfTokenizer.TokenType.EndDic) {
currentLevel--;
break;
}
if (tokens.getTokenType() != PdfTokenizer.TokenType.Name) {
tokens.throwError(PdfException.DictionaryKey1IsNotAName, tokens.getStringValue());
}
PdfName name = readPdfName(true);
PdfObject obj;
if (PdfName.Contents.equals(name) && searchInV && contentsLevel == currentLevel) {
long startPosition = tokens.getPosition();
int ch;
int whiteSpacesCount = -1;
do {
ch = tokens.read();
whiteSpacesCount++;
} while (ch != -1 && PdfTokenizer.isWhitespace(ch));
tokens.seek(startPosition);
obj = readObject(true, objStm);
long endPosition = tokens.getPosition();
if (endPosition == contentsEnd && startPosition + whiteSpacesCount == contentsStart) {
rangeIsCorrect = true;
}
} else if (PdfName.V.equals(name) && !searchInV && 1 == currentLevel) {
searchInV = true;
obj = readObject(true, objStm);
searchInV = false;
} else {
obj = readObject(true, objStm);
}
if (obj == null) {
if (tokens.getTokenType() == PdfTokenizer.TokenType.EndDic)
tokens.throwError(PdfException.UnexpectedGtGt);
if (tokens.getTokenType() == PdfTokenizer.TokenType.EndArray)
tokens.throwError(PdfException.UnexpectedCloseBracket);
}
dic.put(name, obj);
}
return dic;
}

@Override
protected PdfObject readReference(boolean readAsDirect) {
return new PdfNull();
}
}
}

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