private void PrepareEncryptionDictRev2345(string ownerPassword, string userPassword,
PdfEncryption encryptionDictionary, int permissionInt, Document document,
int revision, int length)
{
var idArray = document.File.ID;
//check if the document has an id yet. If it does not then generate one
if (idArray == null || idArray.BaseDataObject.Count < 2)
{
DateTime Jan1st1970 = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
using (var md = MD5.Create())
{
BigInteger time = new BigInteger((DateTime.UtcNow - Jan1st1970).TotalMilliseconds.ToString());
md.Update(time.ToByteArray());
md.Update(Charset.ISO88591.GetBytes(ownerPassword));
md.Update(Charset.ISO88591.GetBytes(userPassword));
md.Update(Charset.ISO88591.GetBytes(document.Information.ToString()));
var finBlock = Charset.ISO88591.GetBytes(this.ToString());
PdfString idString = new PdfString(md.Digest(finBlock));
idArray = new FileIdentifier();
idArray.BaseID = idString;
idArray.VersionID = idString;
document.File.ID = idArray;
}
}
PdfString id = idArray.BaseID;
byte[] ownerBytes = ComputeOwnerPassword(
Charset.ISO88591.GetBytes(ownerPassword),
Charset.ISO88591.GetBytes(userPassword), revision, length);
byte[] userBytes = ComputeUserPassword(
Charset.ISO88591.GetBytes(userPassword),
ownerBytes, permissionInt, id.GetBuffer(), revision, length, true);
encryptionKey = ComputeEncryptedKey(Charset.ISO88591.GetBytes(userPassword), ownerBytes,
null, null, null, permissionInt, id.GetBuffer(), revision, length, true, false);
encryptionDictionary.OwnerKey = ownerBytes;
encryptionDictionary.UserKey = userBytes;
if (revision == 4)
{
PrepareEncryptionDictAES(encryptionDictionary, PdfName.AESV2);
}
}
/**
* This will encrypt a string.
*
* @param string the string to encrypt.
* @param objNum The object number.
* @param genNum The object generation number.
*
* @throws IOException If an error occurs writing the new string.
*/
public void EncryptString(PdfString pdfString, long objNum, int genNum)
{
using (var data = new MemoryStream(pdfString.GetBuffer()))
using (var buffer = new MemoryStream())
{
if (EncryptData(objNum, genNum, data, buffer, false /* encrypt */))
{
pdfString.SetBuffer(buffer.GetBuffer());
}
}
}
private byte[] GetDocumentIDBytes(PdfArray documentIDArray)
{
//some documents may not have document id, see
//test\encryption\encrypted_doc_no_id.pdf
byte[] documentIDBytes;
if (documentIDArray != null && documentIDArray.Count >= 1)
{
PdfString id = (PdfString)documentIDArray.Resolve(0);
documentIDBytes = id.GetBuffer();
}
else
{
documentIDBytes = new byte[0];
}
return(documentIDBytes);
}
/**
* This will decrypt a string.
*
* @param string the string to decrypt.
* @param objNum The object number.
* @param genNum The object generation number.
*
* @throws IOException If an error occurs writing the new string.
*/
private void DecryptString(PdfString pdfString, long objNum, long genNum)
{
// String encrypted with identity filter
if (PdfName.Identity.Equals(stringFilterName))
{
return;
}
using (var data = new MemoryStream(pdfString.GetBuffer()))
using (var outputStream = new MemoryStream())
{
try
{
if (EncryptData(objNum, genNum, data, outputStream, true /* decrypt */))
{
pdfString.SetBuffer(outputStream.ToArray());
}
}
catch (Exception ex)
{
Debug.WriteLine($"error: Failed to decrypt PdfString of Length {pdfString.GetBuffer().Length} in object {objNum}: {ex.Message}", ex);
}
}
}
/**
* Prepares everything to decrypt the document.
*
* @param encryption encryption dictionary, can be retrieved via
* {@link Document#getEncryption()}
* @param documentIDArray document id which is returned via
* {@link org.apache.pdfbox.cos.COSDocument#getDocumentID()} (not used by
* this handler)
* @param decryptionMaterial Information used to decrypt the document.
*
* @throws IOException If there is an error accessing data. If verbose mode
* is enabled, the exception message will provide more details why the
* match wasn't successful.
*/
public override void PrepareForDecryption(PdfEncryption encryption, PdfArray documentIDArray, DecryptionMaterial decryptionMaterial)
{
if (!(decryptionMaterial is PublicKeyDecryptionMaterial))
{
throw new IOException(
"Provided decryption material is not compatible with the document");
}
SetDecryptMetadata(encryption.IsEncryptMetaData);
if (encryption.Length != 0)
{
this.keyLength = encryption.Length;
}
PublicKeyDecryptionMaterial material = (PublicKeyDecryptionMaterial)decryptionMaterial;
try
{
bool foundRecipient = false;
//Org.BouncyCastle.X509.Extension.
X509Certificate certificate = material.Certificate;
X509CertificateEntry materialCert = null;
if (certificate != null)
{
materialCert = new X509CertificateEntry(certificate);
}
// the decrypted content of the enveloped data that match
// the certificate in the decryption material provided
byte[] envelopedData = null;
// the bytes of each recipient in the recipients array
PdfArray array = (PdfArray)encryption.BaseDataObject.Resolve(PdfName.Recipients);
if (array == null)
{
PdfCryptFilterDictionary defaultCryptFilterDictionary = encryption.DefaultCryptFilterDictionary;
array = (PdfArray)defaultCryptFilterDictionary.BaseDataObject.Resolve(PdfName.Recipients);
}
byte[][] recipientFieldsBytes = new byte[array.Count][];
//TODO encryption.getRecipientsLength() and getRecipientStringAt() should be deprecated
int recipientFieldsLength = 0;
StringBuilder extraInfo = new StringBuilder();
for (int i = 0; i < array.Count; i++)
{
PdfString recipientFieldString = (PdfString)array.Resolve(i);
byte[] recipientBytes = recipientFieldString.GetBuffer();
CmsEnvelopedData data = new CmsEnvelopedData(recipientBytes);
var recipCertificatesIt = data.GetRecipientInfos().GetRecipients();
int j = 0;
foreach (RecipientInformation ri in recipCertificatesIt)
{
// Impl: if a matching certificate was previously found it is an error,
// here we just don't care about it
RecipientID rid = ri.RecipientID;
if (!foundRecipient && rid.Match(materialCert))
{
foundRecipient = true;
var privateKey = material.PrivateKey;
// might need to call setContentProvider() if we use PKI token, see
// http://bouncy-castle.1462172.n4.nabble.com/CMSException-exception-unwrapping-key-key-invalid-unknown-key-type-passed-to-RSA-td4658109.html
//DotNetUtilities.GetKeyPair(ri.AlgorithmIdentifier)
envelopedData = ri.GetContent(privateKey.Key);
break;
}
j++;
if (certificate != null)
{
extraInfo.Append('\n');
extraInfo.Append(j);
extraInfo.Append(": ");
if (ri is KeyTransRecipientInformation)
{
appendCertInfo(extraInfo, (KeyTransRecipientInformation)ri, certificate, materialCert);
}
}
}
recipientFieldsBytes[i] = recipientBytes;
recipientFieldsLength += recipientBytes.Length;
}
if (!foundRecipient || envelopedData == null)
{
throw new IOException("The certificate matches none of " + array.Count
+ " recipient entries" + extraInfo.ToString());
}
if (envelopedData.Length != 24)
{
throw new IOException("The enveloped data does not contain 24 bytes");
}
// now envelopedData contains:
// - the 20 bytes seed
// - the 4 bytes of permission for the current user
byte[] accessBytes = new byte[4];
Array.Copy(envelopedData, 20, accessBytes, 0, 4);
AccessPermission currentAccessPermission = new AccessPermission(accessBytes);
currentAccessPermission.IsReadOnly = true;
CurrentAccessPermission = currentAccessPermission;
// what we will put in the SHA1 = the seed + each byte contained in the recipients array
byte[] sha1Input = new byte[recipientFieldsLength + 20];
// put the seed in the sha1 input
Array.Copy(envelopedData, 0, sha1Input, 0, 20);
// put each bytes of the recipients array in the sha1 input
int sha1InputOffset = 20;
foreach (byte[] recipientFieldsByte in recipientFieldsBytes)
{
Array.Copy(recipientFieldsByte, 0, sha1Input, sha1InputOffset, recipientFieldsByte.Length);
sha1InputOffset += recipientFieldsByte.Length;
}
byte[] mdResult;
if (encryption.Version == 4 || encryption.Version == 5)
{
mdResult = SHA256.Create().Digest(sha1Input);
// detect whether AES encryption is used. This assumes that the encryption algo is
// stored in the PDCryptFilterDictionary
// However, crypt filters are used only when V is 4 or 5.
PdfCryptFilterDictionary defaultCryptFilterDictionary = encryption.DefaultCryptFilterDictionary;
if (defaultCryptFilterDictionary != null)
{
PdfName cryptFilterMethod = defaultCryptFilterDictionary.CryptFilterMethod;
IsAES = PdfName.AESV2.Equals(cryptFilterMethod) || PdfName.AESV3.Equals(cryptFilterMethod);
}
}
else
{
mdResult = SHA1.Create().Digest(sha1Input);
}
// we have the encryption key ...
encryptionKey = new byte[this.keyLength / 8];
Array.Copy(mdResult, 0, encryptionKey, 0, this.keyLength / 8);
}
catch (Exception e)
{
throw new IOException("", e);
}
}
