public void Reset()
{
if (_revision < 5)
{
_ownerHash = calculateOwnerHash(_ownerPassword, _userPassword, false);
_userHash = calculateUserHash(_userPassword);
_encryptionKey = computeEncryptionKey(_userPassword, _length);
if (_revision == 4)
{
_stmF = CryptFilter.AESV2;
_strF = CryptFilter.AESV2;
}
}
else
{
_userHash = computeUserHash(_userPassword);
_ownerHash = computeOwnerHash(_ownerPassword, _userHash);
_encryptionKey = new byte[32];
Random rnd = new Random();
rnd.NextBytes(_encryptionKey);
_ue = computeUE(_encryptionKey, _userPassword);
_oe = computeOE(_encryptionKey, _ownerPassword, _userHash);
_perms = computePerms();
_stmF = CryptFilter.AESV3;
_strF = CryptFilter.AESV3;
}
}
private void readCFM(PDFDictionary CF, string key, out CryptFilter filter)
{
filter = CryptFilter.Identity;
if (CF == null)
{
return;
}
PDFDictionary StdCF = CF[key] as PDFDictionary;
if (StdCF != null)
{
PDFName cfm = StdCF["CFM"] as PDFName;
if (cfm == null)
{
return;
}
switch (cfm.GetValue())
{
case "V2":
filter = CryptFilter.V2;
break;
case "AESV2":
filter = CryptFilter.AESV2;
break;
case "AESV3":
filter = CryptFilter.AESV3;
break;
default:
filter = CryptFilter.Identity;
break;
}
}
}
private void readCryptFilters(PDFDictionary dictionary)
{
PDFName stmf = dictionary["StmF"] as PDFName;
PDFName strf = dictionary["StrF"] as PDFName;
if (stmf == null)
{
_stmF = CryptFilter.Identity;
}
else
{
readCFM(dictionary["CF"] as PDFDictionary, stmf.GetValue(), out _stmF);
}
if (strf == null)
{
_strF = CryptFilter.Identity;
}
else
{
readCFM(dictionary["CF"] as PDFDictionary, strf.GetValue(), out _strF);
}
}
